The Structural Engineer January 2016

Full text

(1)TheStructuralEngineer. January 2016. Volume 94 | Issue 1. The flagship publication of The Institution of Structural Engineers. TUNED MASS DAMPERS REPAIRING MISSILE DAMAGE PI CLAIMS: NOTIFICATION DYNAMIC ANALYSIS STEEL QUIZ. TSE49_01 Cover.indd 1. NEW LEASE OF LIFE A case study in timber repair at Tyneside’s historic Dunston Staiths. 17/12/2015 10:46.

(2) p02_TSE.01.16.indd 2. 14/12/2015 15:58.

(3) ›. www.thestructuralengineer.org. Contents. PAGE 22 VIBRATION ABATEMENT WITH TMDS. TheStructuralEngineer January 2016. PAGE 28 REPAIRING DUNSTON STAITHS. 3. PAGE 42 DYNAMIC ANALYSIS WITH TMDS. TheStructuralEngineer Volume 94 | Issue 1. Upfront. Project focus. Opinion. 5 6 8. 22 Vibration abatement of rectangular, trapezoidal and irregular-shaped joist-framed floors, using tuned mass dampers 28 Conservation compendium. Part 14: Dunston Staiths, Gateshead – a case study in timber conservation and repair 32 Baghdad missile-damaged building brought back to life. 50 Book review: Best Construction Methods for Concrete Bridge Decks – Cost Data 51 Book review: Acoustic Emission (AE) and Related Non-destructive Evaluation (NDE) Techniques in the Fracture Mechanics of Concrete: Fundamentals and Applications 52 Book review: Design of durable concrete structures 53 Verulam. Professional guidance. At the back. Editorial Institution news: President’s end-of-year report Institution news: Council election 2016 Election of members of the Board for 2016–17: second poll David Brohn awarded President’s Award. 10 Institution news: Institution election/transfer/reinstatement list: December 2015 Young professionals excel at Teambuild 2015 12 Institution news: Recognising the contributions of reviewers 14 Industry news. 36 Engineer’s Guide to PI Claims. Part 1: Notification to insurers 38 Managing Health & Safety Risks No. 47: Safe excavation. Technical. Features 16 Constructing the future – the role of bearings. 56 58 60 61 63 64. Diary dates Spotlight on Structures And finally… Products & Services Services Directory TheStructuralEngineerJobs. 42 Simplified dynamic analysis of beams and slabs with tuned mass dampers. Front cover: ©Kari Vickers The Structural Engineer PRESIDENT Alan Crossman CEng, FIStructE, FICE, MCIWEM CHIEF EXECUTIVE Martin Powell EDITORIAL HEAD OF PUBLISHING Lee Baldwin EDITOR Robin Jones t: +44 (0) 20 7201 9822 e: [email protected] EDITORIAL ASSISTANT Ian Farmer t: +44 (0) 20 7201 9121 e: [email protected]. TSE49_03 Contents.indd 3. www.thestructuralengineer.org ADVERTISING. EDITORIAL ADVISORY GROUP. DISPLAY SALES Patrick Lynn t: +44 (0) 20 7880 7614 e: [email protected]. Project focus: Allan Mann, FIStructE Features: Don McQuillan, FIStructE Technical: Chris O’Regan, FIStructE Opinion: Angus Palmer, MIStructE Professional guidance: Simon Pitchers, MIStructE. RECRUITMENT SALES Paul Wade t: +44 (0) 20 7880 6212 e: [email protected] DESIGN SENIOR DESIGNER Craig Bowyer CREATIVE DIRECTOR Mark Parry PRODUCTION PRODUCTION EXECUTIVE Rachel Young. Price (2016 subscription) Institutional: £390 (12 issues incl. e-archive, p&p and VAT) Personal: £125 (12 issues incl. p&p) Personal (Student Member): £40 (12 issues incl. p&p) Single copies: £35 (incl. p&p). Printed by Warners Midlands plc The Maltings, Manor Lane Bourne, Lincolnshire PE10 9PH United Kingdom. © The Institution of Structural Engineers. All non-member authors are required to sign the Institution’s ‘Licence to publish’ form. Authors who are members of the Institution meet our requirements under the Institution’s Regulation 10.2 and therefore do not need to sign the ‘Licence to publish’ form. Copyright for the layout and design of articles resides with the Institution while the copyright of the material remains with the author(s). All material published in The Structural Engineer carries the copyright of the Institution, but the intellectual rights of the authors are acknowledged. The Institution of Structural Engineers International HQ 47–58 Bastwick Street London EC1V 3PS United Kingdom t: +44 (0)20 7235 4535 e: [email protected] The Institution of Structural Engineers Incorporated by Royal Charter Charity Registered in England and Wales number 233392 and in Scotland number SC038263. 17/12/2015 10:47.

(4) Presidential Inaugural Address 2016 “THE ART OF THE POSSIBLE” Alan RL Crossman CEng, FIStructE, FICE, MCIWEM. We are delighted to announce that Alan Crossman CEng FIStructE FICE MCIWEM has been appointed 2016 President of The Institution of Structural Engineers. Alan will give his inaugural address to the Institution at its Bastwick Street Headquarters in London on 15 January. The theme of his address will be “The Art of the Possible”. During his address Alan will discuss his own education and formative career, and REmECTONHOWITCOMPARESTOTODAYSEDUCATIONANDCAREERROUTES He will then outline his priorities as President, which include the importance of promoting OPPORTUNITYANDmEXIBILITYINCAREERDEVELOPMENTTHE)NSTITUTIONSVITALGLOBALROLEINCLUDING HISOWNINTERESTINFORGINGNEWLINKSWITHTHEPROFESSIONIN)NDIA ANDTHENEEDTO make sustainability a vital key element in the profession’s thinking.. Date Time Venue. Price. Friday 15 January 2016 17:30 for 18:00 start The Institution of Structural Engineers, International HQ, 47-58 Bastwick Street, London, EC1V 3PS Free. Annual Institution Events. Conferences & Seminars. programme of conferences and seminars The Institution’s key annual events, many of Awhich have been organised by the Institution and industry partners. running for several decades.. Special Interest Series. Technical Lecture Series. A series of lectures organised in partnership by the Institution and other leading organisations.. A series of technical lectures based upon a key theme, which in 2013 is Materials. Registration is required in advance. To book your place, please visit the events section of the Institution website, www.istructe.org and register before Thursday 7 January lecture theatre. If you have any questions please contact the Events Team at [email protected]. p04_TSE.01.16.indd 4. 17/12/2015 14:02.

(5) › www.thestructuralengineer.org. Upfront Editorial. TheStructuralEngineer January 2016. 5. Upfront In with the new Robin Jones Editor. With the holidays behind us and New Year’s resolutions made, I hope that readers are looking forward to the opportunities and challenges that 2016 will bring. At The Structural Engineer, we are starting the year with a revamp of the magazine’s “At the back” section. As well as “Diary dates” (page 56), you will now also find “Spotlight on Structures” (page 58) here, along with periodic updates on other Institution services and a new, lighter feature – “And finally…” – where we hope to exercise your mind each month. We begin with a steel quiz (page 60). In addition, Professional guidance sees the launch of a new series for 2016. Following on from last year’s articles on risk and contractual liability, insurance broker Griffiths & Armour will be providing a series of articles examining the life of a typical professional indemnity claim. We begin by looking at matters requiring notification to one’s insurers (page ge 36). As ever, feedback on these changes is welcome.. present an article showcasing the use of sophisticated bearings systems (page 16), while Project focus also features the latest part of the Conservation compendium – a case study of timber repair at Dunston Staiths (page 28) – and an article from Baghdad on repairs to the steel frame of a building damaged in a missile strike (page 32). We also bring you a number of letters to Verulam (page 53), with a focus on May 2015’s Project focus article on the Grand Parade balustrade in Bath. I will also take this opportunity to remind regional groups about the Sir Arnold Waters Medal, which is awarded each year to the best paper to have won a regional group prize during the session. If your group would like to submit a paper for consideration, please send it to me at [email protected] by 11 January.. Elsewhere in this issue, we have two articles on tuned mass dampers – one in Project focus (page 22) and one in Technical (page 42). In Features we. The Structural Engineer provides structural engineers and related professionals worldwide with technical information on practice, design, development, education and training associated with the profession of structural engineering, and offers a forum for discussion on these matters promotes the learned society role of the Institution by publishing peer-reviewed content which advances the science and art of structural engineering provides members and non-members worldwide with Institution and industry related news provides a medium for relevant advertising. TSE49_05 Editorial v1.indd 5. The Institution has over 27 000 members in over 100 countries around the world is the only qualifying body in the world concerned solely with the theory and practice of structural engineering through its Chartered members is an internationally recognised source of expertise and information concerning all issues that involve structural engineering and public safety within the built environment supports and protects the profession of structural engineering by upholding professional standards and to act as an international voice on behalf of structural engineers . Finally, following on from Will Arnold’s photo Fi in the November issue, Bob Astley has sent in this th picture in which he enjoys his copy of The Structural Engineer in front of the Burj Al Arab S in Dubai. Keep the images coming! Perhaps we can c come up with a prize for the best entry at the t end of the year.. The Structural Engineer (ISSN 1466-5123) is published 12 times a year by IStructE Ltd, a wholly owned subsidiary of The Institution of Structural Engineers. It is available both in print and online.. Contributions published in The Structural Engineer are published on the understanding that the author/s is/are solely responsible for the statements made, for the opinions expressed and/or for the accuracy of the contents. Publication does not imply that any statement or opinion expressed by the author/s reflects the views of the Institution of Structural Engineers’ Board; Council; committees; members or employees. No liability is accepted by such persons or by the Institution for any loss or damage, whether caused through reliance on any statement, opinion or omission (textual or otherwise) in The Structural Engineer, or otherwise.. 17/12/2015 10:47.

(6) ›. 6. TheStructuralEngineer January 2016. Upfront Institution news. President’s end-of-year report Tim Ibell FREng, CEng, BSc(Eng), PhD, FIStructE, FICE, FHEA 2015 President of The Institution of Structural Engineers. It hardly seems possible that I am writing my end-of-year report as the 2015 President. By the time this article is published, roast turkey and all the trimmings will already be a distant memory, and Alan Crossman will be our 96th President. I know that Alan is extremely excited about the role, and that he will lead the Institution with immense energy and distinction. I would like to take this opportunity to wish Alan all the very best for 2016, and to thank him personally for all his support during 2015. As you might imagine, one of the most frequent questions I received as President was: “Are you enjoying your year?” And, predictably, you will not be surprised to hear that I loved it. I shall miss it greatly, and I recommend the role to you unreservedly! It’s a fabulous privilege to play a senior role, albeit temporarily, in such an extraordinary institution. We enjoy a unique and exceptional reputation worldwide, and we should be very proud of this indeed.. Creativity is fun One of the strengths of our profession is that we lie within the Venn diagram intersection between the professional engineering institutions and the built environment institutions. This wonderful positioning gives us the opportunity to lead collaborations and to influence many more sectors than is usually possible for most professions. This has always been true, but I believe that the accelerating changes which the digital revolution is driving represent potent opportunities for our profession, ensuring that creative invention is paramount. At our International Conference in Singapore in September 2015, Chris Wise suggested that humans should do that which humans are good at. This wonderfully pithy comment could not be truer as a signpost for our profession. Creativity is central to all we do as structural engineers, and will only continue to grow in importance in defining our success in future. But there are two other profoundly important reasons why creativity is so crucial to the underpinning education of the next generation of structural engineers. Firstly, creativity is fun, and “fun” is attractive to all of society. Diversity in our profession starts with understanding the talents which we should be looking for among schoolchildren who might wish to be structural engineers. Are they really only Maths, Further Maths and Physics? I suggest not. I suggest that a breadth of outlook, underpinned, of course, by sound numerical aptitude, is increasingly representative of the sort of talent set which our. TSE49_06-07 Inst news v1.indd 6. profession must attract if it is to stay relevant through the digital revolution. Secondly, profound and deep learning of structural engineering can only take place if students are happy and inspired. Uninspired students require teaching, which will not penetrate. Learning and teaching are different concepts. The embedment of creativity as the bedrock of all student activity ensures inspiration to learn, such that deep technical learning is possible. Without creativity as the bedrock, teaching is necessary, and learning is shallow.. Emerging leaders It was such a pleasure back in November, both in Hong Kong and in London, to shake the hands of new professionally qualified members of the Institution, and to welcome them. What strikes me is that these new members will, in all likelihood, have been transferring skills to some of their senior colleagues since the. 17/12/2015 10:48.

(7) www.thestructuralengineer.org. 7. CREATIVITY IS CENTRAL TO ALL WE DO AS STRUCTURAL ENGINEERS, AND WILL ONLY CONTINUE TO GROW IN IMPORTANCE IN DEFINING OUR SUCCESS IN FUTURE. day they arrived in the workplace. It is likely that the most prevalent examples of this would include the ins and outs of particular types of software and the exploitation of social media. When I arrived in industry as a fresh graduate, I couldn’t teach my senior colleagues anything at all. The transfer of skills occurred from the top down only. Times have changed. This is a new era. Transfer of skills is now also taking place from the bottom up. This is a critical break with the past, and we must recognise it. Our young members are not the future of the Institution. They are already the Institution. The digital revolution requires us to be fleet of foot, and I am quite sure that one such agile requirement is to ensure that our young members are seen as emerging leaders within the Institution in a profound way. I believe that this is crucial for our profession and for the Institution, and I greatly look forward to our emerging leaders playing an ever-increasingly important role. In order for our young members to emerge as leaders in the Institution, however, they need to have wanted to stay in the Institution and make the step from Student to Graduate member. During my year, I was keen to see ideas tabled to ensure that an increasing proportion of new graduates transfer their membership from Student to Graduate grade. I feel we have made real headway in this with the Structural Behaviour Course. Now that it has gone live, all members of the Institution, but particularly Student and Graduate members, can take the online Course as often as they like. In fact, I am using the Course as part of the learning material (and assessment) for first-year students, and I would encourage all academics to consider doing likewise. I am sure that the Structural Behaviour Course will quickly become another compelling reason why our younger members should wish to retain membership of the Institution during their Initial Professional Development. Why wouldn’t they want to demonstrate core competence in structural behaviour to their employer?. President’s Award The concept of ensuring that our graduates have a profound understanding of structural behaviour has a long and interesting history within the Institution. But in the more. TSE49_06-07 Inst news v1.indd 7. modern era, there is one member of the Institution who stands out as a visionary. Dr David Brohn pioneered the “Brohn Test”, as it is affectionately known, in the early 1970s. By evidence-based tracking of the level of understanding of structural behaviour among graduates over several decades, and by relentlessly pursuing the goal to ensure that structural behaviour is learned in universities in an appropriate manner, David has led the way in this quest. His passion for the importance of this issue across the industry was far ahead of its time, and now that the Institution has the Structural Behaviour Course firmly in place, it seems so fitting that David be recognised appropriately for his pioneering work. Therefore, it is with the greatest of pleasure that I have decided that Dr David Brohn should receive the President’s Award for 2015. It is a rare honour, and richly deserved.. Encouraging Fellowship Despite the fact that I am clearly championing the involvement of our younger members in everything we do in the Institution, there is another group of membership which deserves a special comment. It is that group of Members who should really be Fellows. On all my visits around the regional groups in 2015, during which I was treated fabulously without exception, I came across large clusters of highly experienced Members who had not yet submitted their forms to become Fellow. This is the written reminder to my verbal chivvying! We have exceptional Members all over the world, so if you feel that you might be ready for Fellowship, please contact our Membership Department and undertake the upgrade. Our staff will help you through the process, which has become far more streamlined over the years.. Fabulous team Speaking of our staff, I would like to take this opportunity to thank every one of them for their extraordinary commitment to the Institution. Under the leadership of Chief Executive, Martin Powell, and his Directors, we have a fabulous team. I can vouch for that first hand. So, thank you for the daily efforts you put in to ensure that the Institution continues to grow successfully. I know that 2016 will be no different, so a very Happy New Year to all our staff and members!. 17/12/2015 10:48.

(8) ›. 8. TheStructuralEngineer January 2016. Upfront Institution news. Council election 2016 Nominations are sought for candidates for election as: • Vice-President 2017–18 • Ordinary member of Council 2017–19 Information about the role and operation of the Council may be found at: www.istructe. org/about-us/organisation-structure/ council The electoral regions in the UK and the Republic of Ireland are based on Institution regional groups – a map of which can be accessed from the website at: www. istructe.org/near-you/europe/unitedkingdom The regions are: 1 Lancashire and Cheshire 2 Scottish, Northern Ireland and Republic of Ireland 3 Yorkshire and Northern Counties 4 Bedfordshire and Adjoining Counties, East Anglia and East Midlands 5 Midland Counties and Wales. 6 Devon and Cornwall, Western Counties and Southern 7 Thames Valley and Surrey 8 North Thames 9 South Eastern Counties 10 Rest of Europe, Middle East, Africa and the Americas 11 Hong Kong 12 Asia and Pacific The minimum number of ordinary members (continuing in office in 2017 and to be elected) from any electoral region is one (apart from region 11, where because of the size of the electorate, it is two). To fulfil this requirement, at least one ordinary member of Council from each of Region 7 and Region 11 must be elected. Chartered and Incorporated Structural Engineers and Technician Members (who have submitted a current Institution Continuing Professional Development return) are invited to consider standing for election as an ordinary member of the Council. Election of members of the Board for 2016–17: second poll. David Brohn awarded President’s Award. Voting by members of Council 2015 to resolve the tie for the election of the third member of the Board for 2016–17 (reported on 12 November 2015) closed at 12 noon GMT on 2 December 2015. The result is as follows:. Institution Fellow Dr David Brohn CEng has been awarded the President’s Award by the Institution, in recognition of his visionary approach to the education of students and graduates in structural engineering. It is only the second President’s Award ever made. David’s “Brohn Test” is used by educators and employers across the UK to measure and embed an understanding of structural behaviour in students and employees, and his extraordinary efforts have underpinned the Institution’s own new Structural Behaviour Course. Institution President, Professor Tim Ibell, said: “The concept of ensuring that our graduates have a profound understanding of structural behaviour has a long and interesting history within the Institution. But in the more modern. Number of eligible voters: 83 Number who voted: 61 Turnout: 73.5% Glenn R Bell 31 Simon J Pitchers 30. Elected. Susan M Doran Company Secretary and Director of Regulations 2 December 2015. TSE49_08 Inst News v1.indd 8. 2017–19. Fellows (who have previously served on Council and who have submitted a current Institution Continuing Professional Development Return) are invited to consider standing for election as a Vice-President 2017–18. Nomination papers (which must be completed by the candidate and ten other Voting Members) are obtainable from Dr S M Doran and must be submitted by Monday 15 February 2016. Candidates must also complete a candidate information form and supply a photograph. Completed nomination documents can be returned by e-mail to [email protected] or by post. In due course, voting documents will be issued and you will be able to vote either electronically or postally. The results will subsequently be published in The Structural Engineer, in the e-newsletter and on the website. Dr S M Doran Company Secretary and Director of Regulations. era, there is one member who stands out as a visionary. “Dr David Brohn pioneered the ‘Brohn Test’, as it is affectionately known, in the early 1970s, leading the way in evidence-based tracking of the level of understanding of structural behaviour amongst graduates, ensuring that structural behaviour is learned in universities in an appropriate manner. “His passion for the importance of this issue across the industry was far ahead of its time, and now that the Institution has its own Structural Behaviour Course firmly in place, it seems fitting that David be recognised appropriately for his pioneering work. It is with the greatest of pleasure that I have decided that Dr David Brohn should receive the President’s Award for 2015. It is a rare honour, and richly deserved.” Dr Brohn said: “I have been a member of the Institution for over 50 years and it has been a major part of my professional life, so I am pleased and honoured to receive this Award.” Dr Brohn will receive the award at the Institution’s Annual People and Papers Awards Luncheon to be held in London during June 2016.. 17/12/2015 10:48.

(9) www.Lindapter.com. Faster Steel Connections The Type AAF, Lindapter’s ‘all-in-one’ adjustable steelwork clamp, offers high slip resistance capability, ease of installation, anti-corrosion protection and performance, even in low temperature environments. . No drilling or welding required Faster installation = lower costs High slip resistance capacities Independently approved SWL apply in temperatures as low as -60oC. NEW An innovative design allows the clamp to self-adjust to suit a range of flange thicknesses. ®. Established 1934. Get the new Lindapter catalogue, out now! Visit www.Lindapter.com for your copy.. THE STRUCTURAL AWARDS OPEN FOR ENTRIES ON Monday 25 January 2016. Technical Innovation in Steelwork Connections. The Structural Awards showcase the work of the world’s most talented structural designers and projects at the forefront of the industry. Being shortlisted, commended or winning an award is a widely recognised accolade across the construction industry. Please visit The Structural Awards website from Monday 25 January to lnd out how you can get involved this year.. 2016 #StructuralAW16. p09_TSE.01.16.indd 9. Deadline for entries is Friday 22 April 2015.. 17/12/2015 09:31.

(10) ›. 10. TheStructuralEngineer January 2016. Upfront Institution news. Institution election/transfer/reinstatement list: December 2015 At a meeting of the Membership Committee on 3 December 2015, the following were elected/transferred/ reinstated in accordance with the Institution’s Regulations: ELECTIONS Fellow via Eminent Persons Route (3) BASHEER, Paliakarakadu Assen Muhammed ROMO, Jose YOUSEFI AZIMI, Saeed Members (2) GHOSH, Somnath MACMILLAN, Colin Richard Callum Graduate (95) Student Employed (10) TRANSFERS Member/Associate to Fellow (7) BARTON, Ian BUCKLEY, Stephen Philip KELLY, Fergal Shaun LOHMANN, Timothy Gerard SCOTT, Thomas Findlay SPELLER, Dominic Gavin THOMAS, Neil Graduate to Member (1) KIM, Boksun. TREASURE, Paul TSANG, Chiu Wai UDAGAMA PALLEWATTHE, Athula WINTERBOTHAM, Andrew. MURRISH, David. Student Employed (1) BAMSEY, Timothy. Associate-Member (3) BROTHWOOD, Kenneth Reginald GREENWAY, John Charles HARRIS, Richard John. Student Free (44) RESIGNATIONS The Membership Committee has accepted, with regret, the following resignations: Fellow (5) AUBREY, William Harry BROOKS, Robert Anthony MARECHAL, Roger Vernon RICHARDS, Malcolm Alexander SMITH, Richard Anthony Member (13) ALLISON, Robert William BROWN, Gary James CANTY, Leslie Esmond COOKSEY, David Mervyn DALL, James Balfour ECHETA, Chinedum Bennett HARLEY, Robert Anthony HARPER, John Frederick JOHNSON, Brian KELLY, Daniel Herbert KWONG, Shun Hang LEUNG, Chi Ming. Associate (1) FULLARD, Andre. Graduate (6) DEATHS The deaths of the following are reported with regret: Fellow (10) CARTER, Raymond Fred Sidney DEAKIN, Neville Teare DUPENOIS, Charles Emilien FORSBREY, Leonard William JOHNSON, John Richard PETITT, Anthony Leslie TOLBUTT, Alan John TYPROWICZ, Tadeusz WEBSTER, Rodney Michael YOUNG, Richard Charles Member (5) BURTON, Alexander Charles HUMPHREYS, Robert JENKINSON, Anthony Richard OAKLEY, Anthony George SPICE, Reginald Walter. Student to Graduate (85) Student to Student Employed (1) Free Students (976) REINSTATEMENTS Member (11) BLACKMORE, Mark CHAN, Kwong Yan CHAN, Yat Hei CHAU, Kaki DRUMMOND, William George HURLEY, Brian LAI, Chi Kin LAM, Chi Leung MCDAID, Pauric Gerard NG, Hoi Lun STRONG, David Associate-Member (2) PRICE, Richard Albert John THOMSON, Russell Mcdonald Graduate (17) BRADLEY, Fiona Foyer HERBERT, Alexander HINKSON, Christopher HUGHES, Graham KNEVITT, Clayton John KUNG, Wilson Wing Kin MARIANO, Priscillano Jr. MCCLERNON, Marta Karolina MORTIMER, Giles Lewis RAD, Taghi RUSH, David Ian TAI, Chin Keung THOMPSON, David. TSE49_10 Inst News v1.indd 10. Young professionals excel at Teambuild 2015 Teambuild 2015, a construction challenge sponsored by The Institution of Structural Engineers’ Educational Trust, was a big success again this year. The objectives of Teambuild focus on developing skills in leadership, communication and coordination, helping to identify ways to improve teamwork in the construction industry. Eleven teams representing 24 UK top construction firms competed in this year’s competition, which took place in November. Teams were challenged with a brief dominated by infrastructure investment and SMARTcities innovation. The teams were asked to plan, design and present hypothetical proposals based around “Edinburgh gateway” – the complex interchange at Gogar, west of Edinburgh, connecting road, tram, rail and air transport.. In line with the SMARTcities concept, teams were required to make data management and IT a key driver in their schemes. The winning team was “Blue Steel”, with team members drawn from Arup, Price & Myers, Max Fordham and Balfour Beatty. All the team members were under 30 and the majority women. Congratulations to the team, who won a prize of £2000. Competition Judge, John Brennan, FCIOB, Project Director at Skanska Plc, said: “Teambuild is a great event, and it has been very rewarding to observe the teams get together over the demanding tasks. Very similar to real-life project situations, this is a great learning experience for all those taking part.” Entries for the 2016 competition will open in June. Read more about Teambuild at: www.teambuilduk.com. 17/12/2015 10:49.

(11) p13_TSE.01.16.indd 10. 14/12/2015 16:01.

(12) ›. 12. TheStructuralEngineer January 2016. Upfront Institution news. Recognising the contributions of reviewers The Structural Engineer. Brian Uy. Yao Cui. Richard Henry. The Institution is grateful to the following for their work in reviewing articles published in The Structural Engineer during 2015.. Pedro Vellasco. Xianghe Dai. Stephen Hicks. Ahmer Wadee. Mario D’Aniello. Chao Hou. Yong Wang. Antony Darby. Yuner Huang. Chien Ming Wang. James S Davidson. Jianwei Huang. Don White. Buick Davison. Jing-Si Huo. Hua Yang. Dina D’Ayala. Hassan Ibrahim. Ronald Ziemian. Nele De Belie. Ragip Ince. Alphose Zingoni. Jorge de Brito. Mehmet Inel. Adel Abdelnaby. Francisco De Caso y Basalo. Aimar Insausti. Sigrid Adriaenssens. Flavia De Luca. Jeppe Jönsson. Sheida Afshan. Juan Jose del Coz Diaz. Prakash Jain. Cinitha Ajith. Gaetano Della Corte. Michal Jandera. Mitsuyoshi Akiyama. Rajesh Prasad Dhakal. Xiaodong Ji. Mehmet Akköse. Luigi Di Sarno. Huanjun Jiang. M. Shahria Alam. Fabio Di Trapani. Lin Jing. Nicholas A. Alexander. Daniel Dias-da-Costa. Venkatakrishnan Kalyanaraman. Yu-Feng An. Florea Dinu. Hemant Kaushik. Sivakumar Anandan. Samir Dirar. Surendra Kumar Kaushik. Ioannis Anastasopoulos. Sekhar Dutta. Liao-Liang Ke. Mahmud Ashraf. Matthew Eatherton. Zbynek Keršner. Farhad Aslani. Evangelos Efthymiou. M Reza Kianoush. Francis TK Au. Wael El-Dakhakhni. Peter Koteš. Ashraf Ayoub. Ana Espinos. Merih Kucukler. Arash Azadeh. Mark Evernden. Sashi Kunnath. Yu Bai. Ciro Faella. Thomas Löhning. Patrick Bamonte. Jiansheng Fan. Nikos Lagaros. Cilmar Basaglia. Cheng Fang. Dominik Lang. Alemdar Bayraktar. Ahmed Farghaly. Deuck Hang Lee. Jurgen Becque. Mohamed Farhat. Sutat Leelataviwat. Abdeldjelil Belarbi. Behzad Fatahi. Janet M Lees. Rita Bento. Peng Feng. Christian Leinenbach. Adriano Bernardin. Jian Feng. Bing Li. Sherif Beskhyroun. Miguel Fernández Ruiz. Kefei Li. Turhan Bilir. Paulo Flores. Guochang Li. A. H. M. Muntasir Billah. Julio Florez-Lopez. Wei Li. Colin Billington. Dora Foti. Fei-Yu Liao. Luke Bisby. Stavroula D Fotopoulou. Abbie B. Liel. Leon Black. Michalis Fragiadakis. J Y Liew. EDITOR-IN-CHIEF. Dionysios Bournas. Raoul Francois. Andrew Liew. Leroy Gardner. Franco Braga. Fernando Fraternali. Gian Piero Lignola. Jianguo Cai. Khaled Galal. James Lim. ASSOCIATE EDITORS. Alfredo Camara. Wei Gao. Peiyang Lin. Mark Bradford. Colin Caprani. Francois Gautier. Xinpei Liu. Lin-Hai Han. Sandro Carbonari. Siddhartha Ghosh. Siwei Liu. Tim Ibell. Donatello Cardone. Agathoklis Giaralis. Alessandra Longo. Jason Ingham. Katherine Cashell. R Ian Gilbert. Sergio Lopes. Sara Cattaneo. Indrani Gogoi. Adelino Lopes. GUEST EDITOR. Liborio Cavaleri. Charles H Goodchild. Joseph Loughlan. Nuno Silvestre. Omar Chaallal. Zdzisław Gosiewski. Paulo Lourenco. Tak-Ming Chan. John Graham. Xinzheng Lu. REVIEWERS. Sylvain Chataigner. Rishi Gupta. Yaozhi Luo. Mike Banfi. Siauchen Chian. Madhar A Haddad. Colin C. MacDougall. Mark Bradford. Jiunnshyang Chiou. Muhammad Hadi. Lorenzo Macorini. Dinar Camotim. Chang-Geun Cho. Ehab Hamed. Gregory MacRae. Dennis Lam. C Z Chrysostomou. Trey Hamilton. Gennaro Magliulo. Janet Lees. Felice Colangelo. Hong Hao. Mahen Mahendran. Guo-Qiang Li. Marco Corradi. Jiping Hao. Damodar Maity. Jeffrey Packer. Mauro Corrado. Mohammad Amin Hariri-Ardebili. Triantafyllos Makarios. Esther Real. Joao Correia. Kent Harries. Christian Malaga. N E Shanmugam. Daniel Cox. Richard Harris. George C. Manos. Jin-Guang Teng. Jacques Cuenca. Amin Heidarpour. Justin Marshall. EDITORIAL ADVISORY GROUP Allan Mann Don McQuillan Chris O’Regan Angus Palmer Simon Pitchers REVIEWERS Tony Bassett Angus Cormie Brian Ellis David Evans Ian Feltham Peter Finnegan Ian Firth Richard Harris John Lyness Ali Manafpour David Rolton Geoff Sellors Brian Smith Dimitris Theodossopoulos Peter Walker. Structures The Institution would also like to thank all of the following who have contributed to the Structures peer-review process during 2014 and 2015.. TSE49_12-13_List.indd 12. 17/12/2015 10:49.

(13) www.thestructuralengineer.org. 13. José-R Martí-Vargas. Adrian Page. Anastasios Sextos. Aneta Ustrzycka. Joao Martins. Kevin Paine. Bahram Shahrooz. Christina Völlmecke. Mark Masia. Dan Palermo. Therese Sheehan. Hamid Valipour. Fabio Mazza. Alessandro Palmeri. Gang Shi. Els Verstrynge. Finian McCann. Peng Pan. Nadeem Ahsan Siddiqui. Paulo Vila Real. Jason McCormick. S Pantazopoulou. Josivan Silva. Phillip Visintin. Gabriele Milani. Chris Pantelides. Nuno Silvestre. Francesco Vivio. Thomas H Miller. Honggun Park. Bhrigu Singh. Marco Vona. Kyungwon Min. M Pecce. Scott Smith. Zora Vrcelj. Cristopher Moen. Fernando Pelisser. Eleni Smyrou. Yuan-Qing Wang. Massood Mofid. Carlo Pellegrino. Chongmin Song. Facheng Wang. Bashar Mohammed. Yong-Lin Pi. Tian Yi Song. Xiuyong Wang. George Morcous. Rui Pinho. Luigi Sorrentino. Jan Wastiels. Guido Morgenthal. Marco Pisani. Dan Stancioiu. Brad Weldon. Christopher Morley. Amir Poursaee. Mark G Stewart. Rou Wen. Evgeny Morozov. Marco Preti. Tim Stratford. Lydell Wiebe. Masoud Motavalli. Raffaele Pucinotti. Mingzhou Su. Chengqing Wu. Giuseppe Muscolino. Mohamad Qatu. Mei-Ni Su. Yufei Wu. Aman Mwafy. Sertong Quek. Luis Suarez. Lili Xie. Farzad Naeim. Karthik Ramanathan. Haluk Sucuoglu. Pei-Yu Yan. Roberto Nascimbene. Maria Ramirez. John Summerscales. Jun Yang. Mohannad Naser. Gianluca Ranzi. Zhiguo Sun. Jie Yang. Giacomo Navarra. Kim JR Rasmussen. Andrea E Surovek. Kang-Sheng Ye. David Nethercot. Prishati Raychowdhury. Alberto Taliercio. Yong Ye. Charles D Newhouse. Ghani Razaqpur. Zhong Tao. Stylianos Yiatros. Hasan Nikopour. Paolo Ricci. Andreas Taras. Hao Zhang. Taichiro Okazaki. Fey Rob. Arturo Tena-Colunga. Bill Zhang. Kutay Orakcal. Manuel L Romero. Solomon Tesfamariam. Guodong Zhang. John Orr. Ana Ruiz-Teran. Marios Theofanous. Jun Zhang. Ashraf Mohamed Osman. Daisuke Saito. Tetsuo Tobita. Ou Zhao. Yu-Chen Ou. Tatsuo Sawada. Timothy H Topper. Zuo-Zhou Zhao. Togay Ozbakkaloglu. Kostas Senetakis. Jean-Michael Torrenti. Alexandr Zhemchuzhnikov. Osman Ozbulut. Junwon Seo. Alireza Ture Savadkoohi. Looking to increase your customer base? Subscribe to FindanEngineer.com for only £10 a month 4HE)NSTITUTIONOF3TRUCTURAL%NGINEERSISOFTENTHElRSTPORT of call for home owners and organisations looking for a structural engineer. FindanEngineer.com is a free search engine which allows UK homeowners and organisations to lnd structural engineers in their local area. For any structural ENGINEERINGPRACTICELOOKINGTOINCREASEITScustomer base, thiSWEBSITEWILLHELP.. How do I subscribe? 3IGNINGUPISSIMPLE!LLWENEEDISAFEWDETAILSWHIch you caNlLLINONLINE 'OTOWWWlNDANengineer.com. TSE49_12-13_List.indd 13. 17/12/2015 10:50.

(14) ›. 14. TheStructuralEngineer January 2016. Upfront Industry news. SCOSS Alert – Wind Adjacent to Tall Buildings SCOSS has published a new alert – Wind Adjacent to Tall Buildings – because reports to CROSS have raised concerns about the design of temporary works to resist wind loading in urban environments. This alert is aimed at those who design or commission temporary structures that are subject to wind loading and adjacent to tall buildings. Although reports relate to urban environments, temporary structures adjacent to tall buildings in exposed locations may also be adversely affected. Read the full alert at: www.structural-safety.org/media/386216/scoss-alert-wind-adjacentto-tall-buildings-december-2015-final-2-.pdf The Structural-Safety website (www.structural-safety.org) combining CROSS (Confidential reporting on structural safety) and SCOSS (Standing committee on structural safety) has newsletters, a database of reports, information on how to report, alerts and other publications.. Leeds firm first structural engineers to achieve BRE BIM certification A Leeds-based firm of civil and structural consulting engineers is celebrating becoming one of just four companies in the country, and the first practice of civil and structural consulting engineers, to be awarded with a coveted certification. The Building Research Establishment (BRE) Building Information Modelling (BIM) Level 2 Business Systems Certification has been awarded to Adept following a stringent assessment process. The firm is therefore recognised as successfully being able to implement and utilise advanced 3D modelling tools in strict compliance with the Government’s strategy. Adept’s managing director, Erol Erturan, a. BRE BIM Accredited Professional, said: “BIM is a great way of demonstrating to clients that we have the right procedures in place at every level to deliver what are very rigorous Government requirements. It also simplifies the tendering process, as once a business is BIM certified its competence levels are guaranteed. “We are now one of just a handful of firms that have achieved this top BIM certification, which is a fantastic achievement – especially as the majority of small to medium-sized businesses are not at all prepared for the introduction of BIM Level 2 and face being frozen out of Government contracts as a result.”. National BIM survey launched NBS has launched its sixth National BIM Survey, which has become recognised as the industry’s most comprehensive look at the use of Building Information Modelling (BIM). The survey is supported by a broad range of professional bodies. Since 2011, the NBS National BIM Survey has charted the rise in the use and awareness of BIM, as well as highlighting the challenges people face. This year’s survey has been timed in order to get a real picture of how the Government mandate has affected that adoption. A vital resource for UK construction. TSE49_14 Indust News v1.indd 14. professionals and policy makers, the 2015 survey found awareness of BIM was almost universal at 95%, yet the adoption figures reported a slight fall – from 54% to 48%. The report suggested that this could be because the “Late Majority” are late to follow on from the Early Adopters and Innovators, so it will be interesting to see if adoption has accelerated in the last 12 months as the mandate starts to loom. You can complete this year’s NBS National BIM Survey at http:// surveys.ribaenterprises.com/wh/s. asp?k=144777062858. The results of the. NBS survey finds construction disputes still as prevalent as ever NBS has revealed the results of its third major survey into construction contracts and related legal issues. The results show that despite market buoyancy the number of disputes within the construction industry remains unchanged in recent years. In 2012, 90% of respondents thought the number of disputes in the construction industry had increased or stayed the same, and in the 2015 survey that figure was the same, with extensions of time being cited as the main cause. Other aspects of the results were more encouraging, with 62% of respondents reporting that they have been involved in some collaborative working in the last 12 months and most (81%) believing it enabled information sharing and reduced the number of disputes that arose (65%). Building Information Modelling (BIM) has been introduced to address one of the major barriers to collaborative working – the lack of clear definition of responsibilities – but the report suggests that the legal framework needs to evolve to recognise and accommodate the changes this brings. Only 14% of those taking part in the survey currently have BIM fully integrated into contracts. The research also concluded that there have been significant changes in the forms of appointment that people use. The use of bespoke contracts has risen from 42% in 2011 to 51% in 2015 and use of the NEC Professional Services Contract has risen from 15% to 37% over the same period. Organisations are increasingly using contracts that are better suited to higher value, collaborative projects. Figures provided by NBS suggest that there has been an increase in the use of NEC and FIDIC contracts, while use of JCT contracts has fallen. The full report can be viewed at: www.thenbs.com/pdfs/nbs-contracts-andlaw-report-2015.pdf. survey will be published in Spring 2016. The results and commentary from last year’s survey are available at: www.thenbs. com/topics/bim/articles/nbs-national-bimreport-2015.asp.. 17/12/2015 10:51.

(15) › www.thestructuralengineer.org. TheStructuralEngineer January 2016. 15. Features Articles with a broad scope often accompanying a significant Institution award or event.. 16 Constructing the future – the role of bearings In this article, Phil Burge of SKF (U.K.) Ltd describes how sophisticated bearings systems are helping to keep a variety of cutting-edge civil and structural engineering projects in working order: whether it’s adjusting an enormous telescope, ensuring that a church bell keeps ringing, or moving the immense doors on an aircraft hangar, each comes with a challenge of its own.. TSE49_15 Features opener.indd 15. 17/12/2015 10:52.

(16) ›. 16. TheStructuralEngineer January 2016. Feature Use of bearings. Constructing the future – the role of bearings Phil Burge Country Communication Manager, SKF (U.K.) Limited. Civil engineering projects – whether a church bell or a drawbridge – are built on a grand scale. As such, they often require very special bearings. The general perception of bearings is tiny silver balls, whizzing around very quickly in fast-moving industrial machinery such as spindles, fans and drives – or in consumer products such as roller skates and skateboards. However, bearings are not always fast and small. In civil and structural engineering, they are usually the exact opposite – large, slow-moving and capable of supporting huge loads (Figure 1). Some of the most sophisticated bearings systems are helping to keep a variety of cutting-edge projects in working order: whether it’s adjusting an enormous telescope, ensuring that a church bell keeps ringing, or moving the immense doors on an aircraft hangar, each comes with a challenge of its own.. Sliding doors The UK’s Building Research Establishment (BRE) houses the largest enclosed. . Figure 1 Bearings for civil engineering are capable of supporting huge loads. laboratory in the world in the Cardington Airship Hangar. Built in 1928, it can accommodate huge structures – such as the enormous R100 airships that were designed by Barnes Wallis. Following a refurbishment programme, BRE engineers began to experience difficulties sliding open the southern hangar door, which is 55m high and 24m wide and weighs 470t. BRE needed an urgent solution, because the door needs to be opened and closed almost every day. To begin with, the doors – which run on a twin-track system using four sets of fourwheeled bogies mounted on each track – were raised using eight 110t hydraulic jacks, which allowed the wheel bogies to be removed. It took one week to remove each one. An inspection of the bogies on the inner track revealed that the existing bearings had degraded, which had created flats on some of the 760mm diameter wheels, due to them skidding rather than rotating. One bearing was removed, and found to be a poorly. constructed needle roller bearing design that had disintegrated. Most rollers were in a similar condition, while the side plates were almost entirely worn away. BRE could have tried to replace the bearing arrangement with a similar system, but was concerned about the degree of wear on the side plates. So rather than fit an identical system, which might go the same way as the original, it adopted a new design using heavy-duty spherical roller bearings. Adapting and reusing some of the existing bogie components helped to make the new arrangement cost-effective. Engineering analysis revealed that the inner bogies were carrying three-quarters of the door’s weight, equivalent to a load of 33t on each wheel. Track measurements showed that the side plate wear was caused by a difference of 20mm in the height level of the inner and outer rail tracks. To accommodate these massive loads, the refurbishment included detailed redesign plus shaft, housing and wheel re-machining, plus complete assembly of wheel units. By the end of the project, all 16 wheels on four bogies – for one door – had been refurbished, and 32 new bearings fitted. To further save cost, existing shafts and wheels were incorporated into the new design where possible. The new arrangement ensured that all loads were held within the wheeled units – containing both lateral forces and high static loads. This prevented a repeat of the original wear problems. Careful coordination of the removal and re-machining of the wheel sets ensured that the door remained in operation during the redesign. The huge doors now open and close easily, with bearings that are likely to last for at least another 50 years.. Lifting boats On an even larger scale, slewing bearings play a huge part in an enormous water wheel that transfers boats between two canals in Scotland.. TSE49_16-20 Feature v1.indd 16. 17/12/2015 10:52.

(17) www.thestructuralengineer.org. 17. . Figure 2 The Falkirk Wheel uses a pair of 4m diameter, three-row slewing bearings. The Falkirk Wheel (Figure 2), the only structure of its kind in the world, is the centrepiece of the Millennium Link – a £78m project that reconnects the Forth and Clyde Canal with the Union Canal between Glasgow and Edinburgh. It does this by raising and lowering boats by 25m, a process that takes four minutes. The two canals were originally linked by a series of locks, but due to a reduction in commercial traffic they fell into disrepair and it was not feasible to restore them. Instead, a giant water wheel – shaped similarly to a double-headed axe – rotates in a continuous circle, lifting and lowering two 22m long caissons. Each can hold a payload of 300t, which is enough for four boats and the water for them to float on. Supporting the wheel required a new bearing that uses a pair of 4m diameter, three-row slewing bearings – one positioned at either end of the wheel, with outer rings bolted to the support structure and inner. TSE49_16-20 Feature v1.indd 17. rings bolted to the arms. The inner ring of one bearing has gear teeth to transmit the drive to the wheel. Each slewing bearing has three rows of cylindrical rollers: one is for the radial load; and two – with smaller rollers – are for the axial loads. This was an unusual solution, because slewing bearings are usually used in applications with heavy axial loads such as large cranes. They were designed to be positioned on a horizontal axis, and cope with the specified combination of radial and axial loads. When fully loaded, the wheel weighs 1800t – producing a radial load of 9095kN per bearing. The wheel is turned by 10 hydraulically driven gearboxes via the geared slewing bearing. The low friction torque of the antifriction bearings means that a rated torque of only 2972kN is needed to rotate the wheel. What’s more, the energy needed to turn the wheel through a half-turn is just 1.5kWh – the amount required to boil eight. kettles of water. The bearings are supplied with their own integral seals and have a life expectancy of 120 years. Additional seals, of 4m and 2.5m diameter, are designed to withstand the heavy-duty conditions, and prevent water ingress. To reduce wear on bearings and other moving parts, operators ensure that the wheel alternates between clockwise and anti-clockwise rotation. As well as the slewing bearings, the design also includes cross-roller bearings to support idler gears that keep the caissons level at all times. The caissons themselves run on a wheel arrangement on circular rails, with each wheel mounted on two sealed spherical roller bearings.. Bridging the gap Spherical roller bearings are supporting a 40t, 30m opening deck on the Pont Y Werin Bridge in South Wales. The bearing units are part of a hydraulic system that can lift. 17/12/2015 10:52.

(18) ›. 18. TheStructuralEngineer January 2016. Feature Use of bearings. The safe, efficient way in which the span moves relies heavily on the bearing units (Figure 3), which must take almost the entire load of the span and withstand the effects of wind forces – which can be very high when the span is fully opened. They must also resist extremes of temperature and the effects of both rain and salt water. Efficient contact seals help to retain internal grease and exclude moisture and other contaminants.. Ringing the bell. W. Figure 3 Spherical roller bearing units on the Pont Y Werin Bridge must take almost the entire load of the span and withstand the effects of wind forces. the bridge deck to a vertical position of 75° in just two minutes, in wind speeds of up to 25m/sec. The 130m bridge comprises four equal sections, of which one is a lifting span that maintains a clear 20m navigational channel below. Engineering consultancy KGAL designed a mechanism to control the movement of the lifting span based on two hydraulic. rams, whose base end is hinged by pairs of 440mm diameter spherical roller bearings set into a specially engineered deck trunnion. Extra bearings are fitted at the top of the hydraulic rams, allowing them to pivot smoothly as the span opens and closes. The bearings used for the bridge have symmetrical rollers, two window-type steel cages and an inner ring centred via a floating ring between the two rows of rollers.. Even highly traditional engineering structures need an occasional makeover in order to cope with the modern world. A swinging church bell, for example, can exert a force equivalent to four times its own static weight. Whites of Appleton, the UK’s oldest continually trading bell-hanging company, has a number of high-profile installations, including St Paul’s Cathedral in London, Windsor Castle and Canterbury Cathedral. According to Whites, headstock design has changed enormously over the last century – with timber increasingly replaced by steel and cast iron. What has not changed is the need to choose the right bearing according to bell weight.. Correcting errors – and preventing them What happens when things go wrong? Engineers should not forget that the Titanic was dubbed “unsinkable”, while the ultra-modern (for 1940) Tacoma Narrows Bridge in the USA oscillated in heavy wind and collapsed four months after it was built. Sixty years later, pedestrians walking across the new Millennium Bridge in London caused it to wobble – though in this case, the problem was fixed by retrofitting fluid dampers. Root cause analysis (RCA) is a tried and tested method for identifying the reason behind an engineering problem (Figure 4). Usually, it is applied in response to an accident, but it can also be used as a way of designing out failure – or at least minimising its risk. It is very much a proactive operation. It splits into five main areas: problem identification/understanding; possible cause generation; data collection; possible cause analysis; and cause-and-effect analysis. The first – problem identification – requires tools such as flowcharts and performance matrices to get to the root of the problem and its causes. Using this. TSE49_16-20 Feature v1.indd 18. information, a list of possible causes can be generated through methods such as brainstorming – which can identify both problems and their possible solutions. Further to this, methods such as sampling, surveys and check sheets are used to collect reliable RCA data. Possible causes can be analysed through data visualisation, which often reveals that a small number of causes account for the bulk of the problem. The final stage, cause-and-effect analysis, shows that multiple causes can lead to the same problem. The trick is to determine the actual root cause. If sufficient data are available, a probabilistic approach could identify the most likely root cause. The tools available to put RCA into practice are extensive, but the most important thing is to use its principles as a proactive way of introducing necessary actions to prevent accidents and solve problems. At the root of it all is recognising that a problem exists in the first place: if a Figure 4 problem is seen as normal, the situation will Root cause analysis is a tried-and-tested method for never improve. identifying the reasons behind an engineering problem. N. 17/12/2015 10:52.

(19) www.thestructuralengineer.org. 19. At the horizontal position of the swing, the bearings experience a force equivalent to 2.5 times the bell’s static weight. At bottom dead centre, this rises to four times the static weight. This means that bell weight immediately determines what size of bearing is needed. Depending on the exact application, Whites uses one of a number of variants of selfaligning ball bearing – supplied with tapered bores and adapter sleeves for easy mounting and dismounting. These are particularly suited to applications that show misalignment in either the shaft housing or bearing seat. They offer low friction and operating temperatures, reduced vibration and noise levels and – a particular advantage for this type of application – low lubrication needs. The bearings and housings support the bell via two gudgeon pins that extend from either end of the headstock. The assembly is lubricated using a general purpose industrial bearing grease, and completed with Type C felt seals. These suit the semi-external environment and the shaft deflection, and are very good at keeping out pigeon droppings – though this has yet to appear on any specification. It goes to show that, sometimes, a. bearing’s capabilities go beyond the call of duty.. Simulating the High Roller Modelling and simulation can be a key factor in getting the design right, and this was evident in the spindle-and-hub design for the largest observation wheel in the world – the 168m tall High Roller in Las Vegas (Figure 5). Simulation tools were used to evaluate the many factors that influence system behaviour, such as clearance in the assembly, misalignments, supporting structure flexibility and different boundary conditions. The High Roller wheel rotates on a pair of custom-designed spherical roller bearings, each weighing approximately 8.8t. Each bearing has an outside diameter of 2300mm, a bore of 1600mm and a width of 630 mm. The double row spherical roller bearings have 30 rolling elements per row – and a simulation model was used to determine the optimal radial bearing clearance. The structure is based on a 143m diameter tension wheel. As well as the two bearing assemblies, it has four steel support legs, a single braced leg, fixed spindle, rotating hub, tubular rim that is 2m in diameter and 112 locked coil cable. assemblies as spokes. Passenger cabins are mounted on the wheel’s outboard rim and are individually rotated by electric motors to maintain a horizontal cabin floor throughout each full rotation. For the spindle and bearing, there are heavy loads and large housing deformations to be considered: on the observation wheel, loads are 1350t per end; for each of the 56 bottom radial cables, the tension is 132t; for the top 56 cables, it is 47t. Total radial cable tension is 4600t. Design and analysis was split into four phases and used extensive modelling and analysis software to evaluate the complex interaction of all the components in the system and identify key performance indicators. Particular attention was dedicated to the evaluation of the effects of loadings and deformations to the bearing performance in terms of forces and motion. After defining the project and collecting design data in Phase 1, the project moved on to simulation analysis in Phase 2. With a configuration in mind, analysis of bearing performance was carried out using simulation models. The model was built by connecting all types of machine components, such as bearings, shafts, gears and housings. An arbitrary combination of. . Figure 5 Engineers on the High Roller in Las Vegas evaluated the effects of loadings and deformations on the wheel’s bearing performance using simulation models. TSE49_16-20 Feature v1.indd 19. 17/12/2015 10:52.

(20) ›. 20. TheStructuralEngineer January 2016. Ensuring a tight fit Tightening bolts is a mundane – through critical – part of putting together huge structures. Getting this wrong can be a major cause of failure. To try and overcome this, devices such as hydraulic bolt tensioners – either manual or automatic – can ensure it is done in a reliable, repeatable way (Figure 6). The Falkirk Wheel, for example, contains more than 15 000 bolts that are matched up with 45 000 bolt holes. Each of them was tightened by hand. It was originally put together in Derbyshire, dismantled, transported to the site and reassembled. Hydraulic bolt tensioning applies a predetermined axial load to the bolt or stud, and helps to ensure consistency in the face of differing friction coefficients in threads and contact surfaces. Poor assembly is the major cause of assembly failure. In particular, bad or irregular tightening contributes to 30% of all assembly failures, and this rises to 45% when fatigue life is concerned. Potential benefits of using the hydraulic principle to tighten bolts include the facts that: • the tightening preload is accurate and well known, and can be close to the bolt’s elastic limit • it enables simultaneous tightening • tensioners are easier and safer to use than torque wrenches • it lends itself well to automatic machines • it enables good care for the bolted joint assemblies and components • it enables reduction and optimising of bolt diameter • it results in better fatigue behaviour. N. Figure 6 Manual or automatic hydraulic bolt tensioners apply a predetermined axial load to ensure that bolts and studs are tightened correctly. TSE49_16-20 Feature v1.indd 20. Feature Use of bearings. forces, displacements and rotational velocities can be used to define the loads on the components – which can be special (non-linear) elements, as well as arbitrary elements such as shafts and housings. The latter must have a linear behaviour, and their stiffness and damping properties are obtained using the finite element method. Special reduction methods are applied to reduce the number of degrees of freedom, and so reduce the calculation time for analyses. After this, the modelling looked at the effect of structural flexibility on bearing performance, which involved adding the hub and spindle as fully flexible components to the model before performing further simulations. A key part of the design project was to ensure that the bearing assembly would be able to live up to the conditions expected in the real world – so during Phase 3 the sensitivity of the bearing to changes in boundary conditions and internal geometry was performed. Initial optimisation runs identified the possibility of life improvements by varying the roller profile and the shaft/hub stiffness. An optimal design was chosen, after which further simulations of the various loading conditions were evaluated. At the end of the project, the results of all simulations were used to determine the procedures and equipment needed for the installation. Installation procedure simulations were almost identical to actual field assembly. As predicted, the installation needed hydraulic injection assist in order to mount the bearings properly. The predicted axial drive-up that was required to achieve the final mounted internal clearance was within 2% of the calculated value – a very accurate result given the complexity of the hub design.. Staring into space Making astronomical observations is expensive – and it’s not just a case of scouring the sky in the hope of finding something of interest. Research telescopes must be closely controlled, and frequently repositioned: another job that is improved by accurate bearings. Telescope Technologies Limited (TTL), a spin-off from Liverpool John Moores University, has designed a scaled-down telescope with a 2m reflective mirror, which relies on hydrostatic shoe bearings in its horizontal (azimuth) and vertical (altitude) axis positioning system. The bearings are designed to carry heavy loads – with the three used for the horizontal axis supporting 24t. On this axis, two torque motor drives, with 100:1 gearboxes, move the telescopes no faster than 5°/sec. Two altitude axis bearings carry a load of 12t. Meanwhile, a secondary mirror – which is moved in order to change the focal plane – uses recirculating ball bearings to give free-flowing axial movement. A third moving part of the telescope also needs accurate positioning. The acquisition and guidance box contains all the scientific instruments – and directs light to the appropriate one. It does this by constant – and accurate – repositioning, called the science fold mechanism. A specially machined threaded ball screw gives a repeatability to within 3m. These examples are just a selection of the many and varied applications of bearings in construction. In almost every case, their size, accuracy and load-bearing capability win out over speed – and this is unlikely to change. SKF is a leading global supplier of bearings, seals, mechatronics, lubrication systems, and services which include technical support, maintenance and reliability services, engineering consulting and training. Web: www.skf.com. 17/12/2015 10:52.

(21) › www.thestructuralengineer.org. TheStructuralEngineer January 2016. 21. Project focus Peer-reviewed papers focusing on the structural engineering challenges faced during the design and build stages of a construction project.. 22 Vibration abatement of rectangular, trapezoidal and irregular-shaped joistframed floors, using tuned mass dampers 28 Conservation compendium. Part 14: Dunston Staiths, Gateshead – a case study in timber conservation and repair 32 Baghdad missile-damaged building brought back to life. TSE49_21 _Project focus opener.indd 21. 17/12/2015 10:58.

(22) ›. 22. TheStructuralEngineer January 2016. Project focus Vibration abatement with TMDs. Vibration abatement of rectangular, trapezoidal and irregular-shaped joist-framed floors, using tuned mass dampers Reza Kashani PhD, PE, DEICON, Inc., USA. Synopsis. A tuned damping solution was developed to mitigate walkinginduced vibration of joist-framed floors in 25 rectangular, trapezoidal and irregular-shaped rooms in an educational facility. The make-up of the floors was concrete on metal deck, supported by open-web steel bar joists. The floors came in various sizes (800–1200sq.ft) and shapes, with the first resonant frequencies in the 6.5–7.5Hz range. Following the measurement of vibration and finite element analysis of the floors, 50 tuned mass dampers (TMDs) (two for each room) were designed, manufactured and installed to effectively address the vibration challenges of the first structural modes of the floors they were designed for. After installation of the TMDs, the effectiveness of the tuned damping solution was evaluated via further measurements. TMDs effectively dampened the first structural modes of the floors in various rooms and lowered their walking-induced vibration to acceptable levels.. TSE49_22-26 Project Focus v1.indd 22. Introduction Wide column spans, along with the use of high-strength material (less of which would provide the required structural integrity), tend to make modern composite and noncomposite floors flexible and oscillatory. Walking (as well as other human activities) can induce high levels of vibration in such floors. When the traditional floor vibration control solutions, such as adding architectural features, mass and/or stiffness to the floor, are either not practical or ineffective, reactive damping provided by tuned mass dampers (TMDs) is used for quieting vibrating floors. A high level of effectiveness, negligible weight penalty and ease of installation make TMDs a cost-effective and non-intrusive vibration control solution for both new and existing floors. In addition, contrary to the damping that can be provided by nonstructural elements such as partitions, raised floors and panelling, which is not readily quantifiable and may not be an option for a space in which a light fit-out is required, TMDs provide predictable damping and can easily be retrofitted. The installation of TMDs on existing floors is the least disruptive (to the occupants) of any floor vibration control solution. Although by no means exhaustive, a sample of research and applied work in tuned damping of floor vibration is cited here. In a laboratory floor structure, Lenzen (1966)1 used a TMD to add damping to a. single mode. Shope and Murray (1994)2 and also Rottmann (1996)3 used several TMDs to control a few modes of an office floor. Others, such as Setareh and Hanson (1992)4 and Webster and Vaicaitis (1992)5 used TMDs to suppress steady-state floor vibration in a number of applications. Setareh (2002)6 studied the use of semi-active TMDs to control floor vibration. Setareh et al. (2006)7 presented the results of the analytical and experimental studies of a pendulum TMD to control excessive floor vibration. Kashani et al. (2014)8 used TMDs to dampen the first two modes of three large balconies in a performing art centre. In addition to the more traditional passive TMDs, active TMDs and proof mass actuators (also known as active mass dampers) have been recently proposed and used for abating floor vibration9,10. These active devices tend to be more lightweight than an equivalent passive damper (with the same effectiveness). Active devices can also be tuned, and add damping, to multiple modes of vibration of the structure. Moreover, they can readily be re-tuned (either automatically using a self-tuning algorithm or manually) to maintain their optimal tuning in the face of change in natural frequencies of the structure. Successful implementation of tuned damping for a floor requires thorough understanding of the system dynamics, including identification of the dominant modes of vibration in terms of their. 17/12/2015 10:59.

(23) www.thestructuralengineer.org. 23. . Figure 1 First two modes of trapezoidal-shaped floors. of the floors, perceptible vibration was felt, when a single person was walking across and near the middle of the rooms. Stiffening solution As an initial attempt to alleviate the floor vibration issue, the joists in a sample of the rooms were stiffened. This was done by attaching W8 beams to the bottom chord of the joists (similar to adding queen post hangers as suggested in the AISC Design Guide). As in any floor stiffening solution, the goal was to increase the stiffness of the floor and, in turn, raise its natural frequencies. Despite the fact that this solution raised the natural frequencies of the test floors by around 20%, e.g. from 7.4 to 9.1Hz in one of the floors, and thus made the vibration caused by walking less perceptible than before, it did not make it imperceptible. Following this unsuccessful attempt in abating floor vibration sufficiently, a damping solution using TMDs was pursued.. . Figure 2 Power spectral densities measured at two locations on floor of room A202. natural frequencies and shapes. Such understanding requires the development of experimentally verified numerical models, which in turn leads to proper sizing and placement of the TMDs. Acceptability of floor vibration The levels of vibration that can be felt strongly by human occupants of structures are generally of no concern to the integrity of the structure. The primary goal of controlling vibration is to ensure comfort of the occupants. The levels that are deemed acceptable vary depending on environment, usage of the space and the individual sensitivity of occupants. Since it is acceleration that causes a force to be felt in the body of the occupants of a structure, the perceptibility of floor vibration is commonly described in terms of accelerations (expressed in terms of the acceleration due to gravity, g). The peak measured and predicted levels of vibration on construction of the joistframed floors, in response to a single person walking, were higher than would be deemed. TSE49_22-26 Project Focus v1.indd 23. acceptable in a typical office/classroom. According to American Institute of Steel Construction (AISC) guidance11, the target performance of the worst-affected areas of the floors, in office-like environments, in response to one person of average weight walking, is 0.5% g. The case where a number of people are present on the floors, sitting or standing, could be less problematic considering the fact that human bodies add damping to the floor.. Description of floors The floors were made up of 2.75in. of concrete on metal deck, supported by open-web steel bar joists spaced at 3ft on centre. The floors came in various sizes (800–1200sq.ft) and shapes (rectangular, trapezoidal and irregular), with the first resonant frequencies between 6.5 and 7.5Hz, falling in the frequency range where human bodies are most sensitive in perceiving vibration. The large joist spacing and small concrete thickness made the floors susceptible to undesirable vibration. Upon construction. Dynamic analysis and testing In order to design and specify the TMDs, reasonably accurate estimates of the dynamic properties of the floors were acquired numerically (using finite element analysis) and experimentally. Shell elements were used to model the floor (concrete) rigidly offset from beam elements used to model the floor joists. The offset is half the joist depth plus the height to neutral axis of the concrete decking. The dynamic modulus of elasticity was used for the concrete. Finite element modal analysis of the floor models allowed for the prediction of the natural frequencies, their corresponding mode shapes and modal masses. On-site testing enabled the structural model to be verified (and adjusted if need be) and the inherent level of damping in the structure to be measured. The correlated model was then used to assess the effectiveness of the proposed solution. When developing a finite element model of a floor for such purposes, it is good practice to include adjacent structure from the floor area that is being investigated8. The extent of this inclusion depends on the floor system itself. Once the model is built, this assumption can be checked by looking at the modes and the areas that respond in each mode. If the modes of interest do not have significant participation at the boundaries of the model, then the extent of the adjacent structure included in the model can be deemed sufficient. If not, then more adjacent structures should be added until the modes of interest are no longer affected by further additions to the model.. 17/12/2015 10:59.

(24) ›. TheStructuralEngineer January 2016. 24. Project focus Vibration abatement with TMDs. . Figure 4 Measured (blue/solid line) and identified second-order FRF of TMD. S. Figure 3 Schematics of viscous damper’s. a) Maxwell model. b) TMD suspension. c) TMD. TSE49_22-26 Project Focus v1.indd 24. The finite element models of the floors were experimentally verified by measuring the natural frequencies of their lowfrequency modes. A heel-drop simulator was used to perturb the floors at locations where the perturbation coupled most effectively with the target modes. At each excitation location, heel-drop perturbations were repeated three times, and accelerations at two locations on the floor were measured simultaneously (and averaged to produce statistically valid data). Figure 1 shows the shapes of the first two modes and their corresponding frequencies for the floors of the two adjacent, trapezoidal-shaped classrooms, predicted by finite element analysis. The modal masses (normalised to maximum vertical displacement of the mode) were 8 tons for both modes. The measurement locations, A (at the centre of the floor) and B (at ¼–¼ point on the floor), are also highlighted on Fig. 1. Figure 2 shows the power spectral densities of acceleration measured at the two locations of A and B, shown in Fig. 1, in one of the trapezoidal rooms (room A202). Note that point A is almost at the centre of the room and point B is located halfway between point A and the long wall of the room. The presence of both modes, especially at location B, is quite clear from Fig. 2. The natural frequencies of all the floors, including those of room A202, measured experimentally, were in very good agreement with those predicted. numerically. The floor system’s mode shapes were not expected to be particularly different from the predicted one shown in Fig. 1. A certain amount of variation could be expected in terms of degree of participation of connected areas, but not to a degree that would significantly affect the results. The purpose of matching the model to the results was to have an updated analytical platform to work from when assessing the effectiveness of a potential solution. Matching the frequencies of the modes was therefore deemed sufficient, and was achieved by varying the modulus of elasticity of the concrete, which can be expected to vary in practice depending on the amount of cracking.. Design and realisation of TMDs Once the floor finite element models had been verified against the initial testing, they were used to determine the required parameters of each TMD according to the following procedure: • Choose a TMD mass. A larger mass will generally yield more damping and higher bandwidth (to provide robustness in a potential off-tuned case), but an optimal choice that balances requirements, buildability and cost can be made by studying predicted achievable damping for various amounts of mass. Equations for achievable damping can be found in work by Den Hartog (1956)12, among others, which relates to the optimum parameters for adding damping to undamped systems. These equations are. 17/12/2015 10:59.

No results found