OSHA Safety and Health Regulations for Construction Subpart L “Scaffolds” also includes requirements that relate to formwork. The distinction of a structure being classified as either formwork or scaffolding determines what the design requirements are for the system. The primary requirement that impacts formworkdesign is found in §1926.451(a)(1), “Except as provided in paragraphs (a)(2), (a)(3), (a)(4), (a)(5) and (g) of this section, each scaffold and scaffold component shall be capable of supporting, without failure, its own weight and at least 4 times the maximum intended load applied or transmitted to it” . The OSHA definition of a scaffold is found in §1926.450(b): “Scaffold means any temporary elevated platform (supported or suspended) and its supporting structure (including points of anchorage), used for supporting employees or materials or both” . Some work platforms are attached to and supported directly by the formwork system. OSHA refers to these types of work platforms as form scaffolds and provides the following definition in §1926.450(b): “Form scaffold means a supported scaffold consisting of a platform supported by brackets attached to formwork” . These work platforms are considered scaffolding and the
Size, shape, and alignment of concrete walls and columns depend on accurate construction of the vertical forms. Vertical formwork needs to be strong enough to handle construction loads safely and stiff enough to maintain its shape under full load. Forms need to be constructed to withstand handling and reuse without losing their dimensional integrity (Nemati, 2007). Formwork must be rigid enough under construction loads to maintain the designed shape and alignment of the concrete element. If the forms deflect excessively, deformations in the concrete surface may require expensive chipping and grinding. If the forms move out of place, the misalignment can destroy the integrity of the structure or affect installation of the structural frame or the building’s facade (ACI, 2005). The quality of the surface finish of the concrete is directly affected by the forms and form material. Poor formworkdesign or workmanship will lead to form concrete leakage and rough finishes. If the forms do not produce the specified finish, considerable corrective work such as grinding, patching, rubbing, or coating may be required (ACI, 2005).
Typically, the components of formwork are sheathing, studs, joists, wales, stringers, shores, and tie rods. Sheathing retains the concrete and is supported by studs in vertical forms and joists in horizontal forms. Studs are supported by wales and joists by stringers. The wales are held in place by tension members such as tie rods and stringers are supported by shores or posts. Other than tie rods and shores, the other components of the formwork structurally behave like beams, whether being horizontal or vertical. Beam formulas are used to analyze the formwork components. Below the formulas for bending, deflection and shear are introduced. From these formulas the quantities of l, the safe span is calculated. In formworkdesign, the smallest value of l calculated for each category of bending, deflection and shear is used as the safe span that satisfies all conditions.
Several factors are put into consideration in the design of forms in order to avoid structural failures and achieve a balance of certain requirements such as containment, strength, resistance to leakage, accuracy, ease of handling, finish and reuse potential, access for concrete and economy. A rational approach to formworkdesign based on simplified assumptions and approximate beam formulas is sufficiently adequate when designing formwork
FormworkDesign, BIM, Parametric Modelling, Design Automation, Formwork Visualisation.
The design process in Building Information Modelling (BIM) environment generates useful and informative data which can be used for several downstream activities such as analysis of alternatives (Langroodi and Staub-French, 2012) and virtual construction (Popov et al., 2010). Previously research has been carried out to use BIM data for energy analysis (Ahn et al., 2014; Tse, Wong and Wong, 2005), structural analysis (Cavieres, Gentry and Al-Haddad, 2011; Lopez, 2011), sustainability analysis (Azhar et al., 2011; Jalaei and Jrade, 2015; Wu and Issa, 2012), facility management (Kang and Choi, 2015; Lin, Su and Chen, 2014; Becerik- Gerber et al., 2012) and many similar activities (Yalcinkaya and Singh, 2015). The use of BIM data reduces the efforts to remodel data in an analysis application, while significantly reducing errors and coordination issues (Sawhney and Maheswari, 2013). The BIM data can also be used for automating design evaluation and code compliance checks (BCA, 2013; Sanguinetti et al., 2012; Cheng and Das, 2014; Sinha et al., 2013). Approaches have been developed to perform rule checking for acoustical design (Pauwels et al., 2011) and many more performance evaluation activities. The latest trends in the domain include the use of BIM data for automating construction tasks such as site planning (Kumar and Cheng, 2015; Kannan and Santhi, 2013) and preparing a layout for construction safety (Zhang et al., 2013; Azhar and Behringer, 2013; Ding, Zhou and Akinci, 2014). Moreover, BIM authoring tools can also be used for generation of design alternatives based on available constraints (Abrishami et al., 2014). The BIM authoring tools have the potential to advance the Architecture, Engineering and Construction (AEC) industry by automating redundant and repetitive design tasks and calculations. These approaches allow designers to expend more efforts on decision-making tasks (Sawhney, 2014).
Formwork is a temporary construction; however care must be taken to prevent damage to permanent work. There are some general principles governed formworkdesign and construction like Quality, Safety, Economy. Based on the title of my research, this dissertation is to research on what are the factors that has been considered in determining the choice of formwork. Throughout the research you will see various types of formwork details and also the factors, the system or the methods that are being used in our Construction Industry nowadays. The purpose of determining the choice of formwork mainly is to reduce the cost of construction. The cost of formwork is occupying a big percentage in the total construction cost, as we do not allow to reduce the cost by changing other building components requirement due to they were all specified in the Contract Documents, therefore choose and plan the system of formwork wisely will greatly reduce the cost of construction. In addition, choosing a proper system of formwork will also reduce the time of construction and the wastage thus reduces the total construction cost. Therefore, choosing the system of formwork wisely is a good practice for every construction work.
Other systems used on this project included the ACS – Automatic Climbing System, SKYDECK slab formwork system and VARIO Wall Formwork System to construct a typical floor footprint of 11,000 sq.ft (1,000 sq.m). The PERI Automatic Climbing System combined with VARIO wall formwork were used for the elevator and stair core. Using the PERI ACS climbing system eliminated the necessity for a crane when moving to the next pour sequence. PERI also provided a separate ACS system with custom steel wall formwork required for the architectural exterior columns and spandrel beams.
Due to the fine tolerances achieved in the machined metal formwork components, consistent concrete shapes and finishes are obtained floor after floor, building after building, confirming to the most exacting standards of quality and accuracy. This allows plumbing and electrical fittings to be prefabricated with the certain knowledge that there will be an exact fit when assembled. The dimensional accuracy at the concreted work also results in consistent fittings of doors and windows.
Using geo-textiles and membranes to suspend between the grid laths, shotcrete can be applied onto the surface to form the shell. The vocabulary of shell aesthetics is apparent and draws references to the sensibilities of structures cast from fabric formwork. (Figure 19). The use of a flexible membrane to create undulations, creases, cuts on a curved surface in these instances is a very attractive possibility. This have the potential to contemporarize this technology and introduce it into the technological mainstream to revive the concrete shells again.
AF Anchorage: A unique VSL design for the lower non-stressing anchorage of the vertical tendons where access to the underside of the tank is not possible. It is made of cast iron and is another of VSL’s new generation of anchorages. The strands, equipped with compression fittings, are installed one-by-one, the first-stage grouting of the anchorage (using VSL’s high performance AF Anchorage Grout with a compressive strength in excess of 100 MPa) is carried-out, the tendon is stressed and finally the free length of the tendon is grouted.
drocarbons that compose mineral oils. The latter have an essentially physical mode of action. They adhere to the formwork and, as they are hydrophobic, the fresh con- crete does not make contact with the walls formwork. Vegetable release agents, however, have a physico- chemical action that has not been extensively described. In the presence of superplasticizer in concrete, these pro- ducts acquire new functional properties and a mode of action specific to them. We therefore conducted a study to explain the mechanisms that occur at the concrete/oil interface when concrete is placed.
India. Abstract-- Controlled Permeability Formwork (CPF) is one of the recently developed techniques for improving the cover zone of concrete. This technique is to drain the surface water and entrapped air from the near surface of fresh concrete by retaining the cement and fine particles. This ensures reduced water-cement ratio, decreased surface porosity and higher cement content near the cover zone. CPF action creates smooth surface free from blow holes, pinholes. By using CPF, the quality of near surface portion of concrete can be improved and the aggressive agencies can’t find an easy entry in to the concrete to destroy concrete structures. Though CPF liner is proved to be effective in normal concrete an attempt has been made in the present work to check the effectiveness of CPF liner in self-compacting concrete (SCC).
Chien-Ho KO et al., (2015) The objective here is to use manufacturing strategies of lean to formwork in order to lessen waste. Case study is carried, in which the waste elements are identified using a lean tool (value streaming) and a lean construction model is adopted in which, Andon culture is used to establish an on-web page pleasant manipulate lifestyle, making workers of shuttering to achieve help immediately each time when trouble takes place. Adding to this, operations of formwork are drawn through the Kanban method in order to decrease mold stock and attain uninterrupted production waft. Improving formwork exceptional relies upon on adopting a tradition of continuous getting to know and improvement. With the Andon way of life and Kanban gadget waste can be eliminated. .
Abstract: Self-consolidating concrete (SCC) is a recently developed innovative construction material. SCC fills in a formwork without any vibrating consolidation, which allows us to eventually achieve robust casting. However, high formwork lateral pressure exerted by SCC is a critical issue regarding its application as cast-in-place concrete. In order to control the risk caused by high formwork pressure, a comprehensive prediction model for the pressure was previously proposed, investigated, and validated with various SCC mixtures. The model was originally designed to simulate the intrinsic pressure response of SCC mixtures while excluding other extrinsic influencing factors such as friction and flexibility of the formwork. The model was then extended to con- sider extrinsic factors such as friction between SCC mixtures and formwork. In addition, other interesting topics for peak formwork pressure and mineral admixture effects were summarized in the paper.
To prevent injuries and save the lives of construction workers, there has been considerable interest in improving worksite safety through safer design and work method statements using Building Information Modelling (BIM). BIM provides 3D electronic information about the final form of facilities such as infrastructure and buildings. Through integrating such 3D information, BIM can represent all structural components such as beams, columns, walls and floors. BIM can also encapsulate information other than physical properties such as construction sequencing and safety information. An integrated element or component is called a BIM object. To improve construction safety, some researchers investigated the application potential of BIM for safer construction design (e.g. clash detection between sequential activities) and safety planning (e.g. 3D design review for construction risk analysis and mitigation) (Furst 2009; Ku and Mills
The findings demonstrate the difficulties faced when using conventional formwork systems and the importance of ASF due to its advanced technological impact and time saving. Kim et al. (2012) have also reported that ASF had a good potential for managing cost, time and government requirements. Research findings declare a positive relationship between LP with ASF and LPFs and the impact on LPNs due to varying effects of LPFs. Similarly, Smith and Hanna (1993) found a direct relationship between LPFs and ASF in LPHs. Research findings stress the necessity and importance of LPNs, even though it cannot affect the market rate in the short term. Vliet (2011) highlighted the need for a norm to maintain the required labour force, the best work practices, minimum disturbances and for creating a benchmark to facilitate the standardisation and efficient evaluation of LP. The research was initiated against a background where issues related to ASF of LHPs were crucial, and there was no value adding practice conducted in the industry to enhance the advanced nature of ASF. Results indicate the real benefits of ASF through LPNs. These two different concepts have been connected here, based on the LPFs and other related aspects, in order to provide an effective and efficient atmosphere in the construction industry.
When comparing the plots of the pressures versus height for each of the mixtures and rates of placement, it was obvious that the rate of placement played a significant role in the lateral formwork pressure. While the two SCC batches placed at an equal rate exhibited slightly higher pressures, the two placed at a lower rate produced significantly less pressure than the normal concrete. After viewing these results, the researchers created a plot of form pressure versus casting rate and found that the relationship was relatively linear. The only exception to this pattern was casting number 5, which exhibited significantly higher pressures than any other cast. The author stated that this was because the concrete in this batch was placed directly in the form after mixing and was both younger and more flowable than the other 6 mixtures. This finding seems to be a clear indicator that batch properties such as slump flow and age can play a significant role in formwork pressures in addition to the rate of placement, but these properties were not studied significantly in this particular study. The data also indicated that the mixture composition could not be correlated with a higher or lower form pressure.
Theoretically, there is a clear-cut relationship between ASF and the LPNs and effect of LPFs on both which has not been previously identified. Economically, LPNs govern LP, mitigate the shortcomings of excess labour use, help to timely completion of the project and ultimately have an impact on future employment market rates. Notably, LPNs motivates construction industry practitioners and facilitate self-commitment and mental health. This affects the well-being of construction professionals and the labourers. The findings have already developed a foundation for influencing the attitudes of clients and construction professionals regarding ASF compared to conventional formwork systems. Psychologically, this creates a friendly environment for the parties, enabling them to work in a peaceful environment with fewer disputes.
During construction of concrete buildings, it is necessary to share the construction loads of workers, materials, forms, and freshly placed and early age concrete over several previously cast floors. The loads at the upper level during construction are typically greater than the single floor design strength of the completed structure and the strength is less due to the early age of the concrete. Distributing the loads over several lower floors can achieve a state that is safe for the workers and avoids damage to the structure. A typical traditional construction cycle would often include one set of shores and two sets of reshores. However, this depends upon the rate of strength gain of the concrete used, the loadings for which the structure was designed, and the length of time available for the project.