Inclusion of steel fibers to concrete progresses the flexural and tensile capacities of concrete. Consequently the shearcapacity of concrete flexural members improve. Predicting the shearcapacity of concrete beams containing steel fiber is an important issue not only in structural design but also to retrofitting of existing structures. Since there are several variables to assess the shearcapacity of steel fiber reinforcedconcrete (SFRC) beams, presenting a suitable equation is a complicated task. The aim of the present paper is to evaluate an empirical formulae based stepwise regression (SR) method for shearcapacity of SFRC beams. A series of reliable experimental data has been provided from literatures for model development. The obtained results based SR model were compared with experimental data in training and testing state. A practical formulae based SR method has been developed for shearcapacity assessment of SFRC beams. Besides, several equations based models also presented to compare with the equation based SR model. The comparison showed the SR formulae gives the most exact accuracy than others in terms of shearcapacity assessment of SFRC beams.
There is a few design and prediction models related to the punching shear strength of concrete slabs reinforced with FRP composite bars. This paper evaluates the accuracy of the available punching shear equations for FRP-RC slabs in the models of CSA S806 (CSA 2012) , ACI-440.1R-15 (ACI 2015) , BS 8110 (BSI 1997) , JSCE (1997) , El-Ghandour et al. , Matthys and Taerwe , Ospina et al.  and El-Gamal et al.  . The accuracy of the design equations and different models was assessed by comparing their predictions against the experimentalresults. This paper also presents a simple yet improved model to calculate the punching shearcapacity of FRP-reinforcedconcrete slabs. The performance of the proposed model is also compared to that of punching shear design provisions and a number of models propsed by some researches.
Although further experimental data is required to verify the above proposed failure criteria, the results suggest that while at the lower strain-rates the increase from the static case is only by 7%, for strain-rates of 100 and 300/s, the respective increases are 33% and 73%, which are very signi ﬁ cant. For strain-rates higher than 300/s, which can be the case in ballistic problems, the strain-rate dependent relationships for the materials used in the model and the contribution of aggregate interlock would need to be reviewed to consider additional mechanisms such as aggregate crushing. Fig. 11. Idealisation of aggregate particles into spheres (after ).
The typical failure mode of the beam is illustrated in Fig. 3, whereas Table 3 summarized the prediction and experimentalresults of all the tested beams. Beam failed on diagonal tensionshear experienced formation of diagonal crack in the shear span zone followed by concrete crushing in the loading point zone (BGM-03), sudden formation of diagonal crack in the shear span zone followed by beam failure (BGM-04) or formation of diagonal crack growth gradually in the shear span zone followed by beam failure after yielding of longitudinal reinforcement (BSM-03 and BSM-04).While other beams which failed on flexural experienced by rupture of tensile longitudinal reinforcement or concrete crushing on the top of compression zone. For both beam types, the amount of flexural crack in case of beam with shorter shear span length less than that beam with longer shear span length. Also, the occurrence of diagonal shear crack was not clearly seen in the shear span zone.
The typical failure mode of the beam is illustrated in Fig. 3, whereas Table III summarized the prediction and experimentalresults of all the tested beams. Beam failed on diagonal tensionshear experienced formation of diagonal crack in the shear span zone followed by concrete crushing in the loading point zone (BGM-03), sudden formation of diagonal crack in the shear span zone followed by beam failure (BGM-04) or formation of diagonal crack growth gradually in the shear span zone followed by beam failure after yielding of longitudinal reinforcement (BSM-03 and BSM-04).While other beams which failed on flexural experienced by rupture of tensile longitudinal reinforcement or concrete crushing on the top of compression zone. For both beam types, the amount of flexural crack in case of beam with shorter shear span length less than that beam with longer shear span length. Also, the occurrence of diagonal shear crack was not clearly seen in the shear span zone.
Rupert G. Williams et, al  displayed an attempt to find out numerical reaction of a seismically designed SDOF structure to blast loading. A portal frame was designed in Northen Trinidad to resist the blast load. 500 kg of charge weight of TNT was used and different standoff distance of 45, 33, 20 meters were taken. By using empirical methods the blast load was determined. From this study it is showed that the designed SDOF model entered the plastic region due to the blast load in a critical standoff distance. Edward Eskew & Shinae Jang  carried out a systematic approach determine the causes and results of terrorist attacks. The better way to understand the impact of terror is to understand the nature of the attack. Different type of explosions, including physical, chemical, electrical and nuclear was provided in this report. Impact from an explosion is obtained from analytical and experimental methods. Analysis technique for a damaged structure is also explained in depth. From this knowledge of an explosion the damage of the structure can be determined or detailed models could be developed to calculate the damage that has happened already.
Abstract—This study aims to determine the efficiency of using Fiber Reinforced Polymers (FRP) systems to strengthen the slab–column connections subjected to punching shear. The used strengthening systems consisted of external FRP stirrups made from glass and carbon fibers. The stirrups were installed around the column. Also, external steel links were used as a conventional strengthening method for comparison. Over the last few years, the use of FRP for strengthening of concrete structures has been investigated by many researchers, whichconcerning with the strengthening of reinforcedconcrete slabs, beams and columns. The use of FRP in strengthening concrete slabs in flexure is done by bonding it to the tension face of the slabs. The use of FRP for strengthening the flat slabs against punching shear can be considered as a new application. This research shows the results obtained from an experimental investigation of 4 half-scale two-way slab-column interior connections, which were constructed and tested under punching shear caused by centric vertical load. The research included one unstrengthened specimen, which considered as control specimen, one specimen strengthened with steel links, one specimen strengthened with external stirrups made from Glass Fiber Reinforced Polymer (GFRP), and one specimen strengthened with external stirrups made from Carbon Fiber Reinforced Polymer (CFRP). So, the type of strengthening material is the basic parameter in this study. The experimentalresults showed a noticeable increase in punching shear resistance and flexural stiffness for the strengthened specimens compared to control specimen. Also, the strengthened tested slabs showed a relative ductility enhancement. Finally, equations for punching shear strength prediction of slab-column connections strengthened using different materials (Steel, GFRP & CFRP) were applied and compared with the experimentalresults.
ABSTRACT: This study is part of a larger research work aimed to study the effects of fiber content, fiber type (corrugated shape and hooked-end), amount of web reinforcement and axial compression stress, on the shear behavior of high strength fiber reinforcedconcrete (HSFRC) beams. To the author’s knowledge, the effect of applying axial compression forces, to the HSFRC beams, has not yet been studied. Nineteen simply supported HSFRC beams were subjected to axial compression forces and tested under two-point vertical loading for three values of shear span to depth ratio. It was found that the shear strength of beams subjected to axial compression stress level equals 0.1, is higher than that in the literature for beams tested without applying axial stress by a range of 22% -98%. Increasing the axial compression stress level to 0.2 led to an increase in the first crack load, ultimate load by 24% and 10%, a reduction in the deflection by (19-30%), compared with those subjected to axial compression stress level equals 0.1. In addition, a combination of web reinforcement and fibers resulted in a significant increase in the cracking and ultimate loads by 123 and 59%, respectively, over those of the reference beam. A new formula is proposed for predicting the experimentalshear strength of HSFRC beams subjected to axial compression forces. The results obtained by the proposed formula are in better agreement with the test results when compared with the predictions based on the empirical equations proposed by other investigators.
This paper presents the results of an extensive experimental campaign on 16 flat-slab specimens with and without punching shear reinforce- ment. The tests aimed to investigate the influence of a set of mechan- ical and geometrical parameters on the punching shear strength and deformation capacity of flat slabs supported by interior columns. All specimens had the same plan dimensions of 3.0 x 3.0 m (9.84 x 9.84 ft). The investigated parameters were the column size (ranging between 130 and 520 mm [approximately 5 and 20 in.]), the slab thickness (ranging between 250 and 400 mm [approximately 10 and 16 in.]), the shear reinforcement system (studs and stirrups), and the amount of punching shear reinforcement. Systematic measurements (such as the load, the rotations of the slab, the vertical displace- ments, the change in slab thickness, concrete strains, and strains in the shear reinforcement) allow for an understanding of the behavior of the slab specimens, the activation of the shear reinforcement, and the strains developed in the shear-critical region at failure. Finally, the test results were investigated and compared with reference to design codes (ACI 318-08 and EC2) and the mechanical model of the critical shear crack theory (CSCT), obtaining a number of conclu- sions on their suitability.
Abstract: This paper presents the results of a two-phase experimental program investigating the punching shear behavior of FRP RC flat slabs with and without CFRP shear reinforcement. In the first phase, problems of bond slip and crack localization were identified. Decreasing the flexural bar spacing in the second phase successfully eliminated those problems and resulted in punching shear failure of the slabs. However, CFRP shear reinforcement was found to be inefficient in enhancing significantly the slab capacity due to its brittleness. A model, which accurately predicts the punching shearcapacity of FRP RC slabs without shear reinforcement, is proposed and verified. For slabs with FRP shear reinforcement, it is proposed that the concreteshear resistance is reduced, but a strain limit of 0.0045 is recommended as maximum strain for the reinforcement. Comparisons of the slab capacities with ACI 318-95, ACI 440-98 and BS 8110 punching shear code equations, modified to incorporate FRP reinforcement, show either overestimated or conservative results.
Previous researcher, Marsono (2000) has conducted an experimental work on small scaled model of various types of shear walls structure. Results from the experiment in the form of stresses and strains, crack distributions and ultimate strength then used to establish the analytical method (Continuous Connection Method, CCM) of analysis. The non-linear finite element analysis (NLFEA) was performed as a tool to affirm the experimentalresults and the analytical mode of failure and ultimate strength predictions. The experimental and NLFEA results were in very close agreement in predicting the ultimate strength and mode of failure of coupled shear wall structure.
Reinforcedconcrete buildings exhibiting tri-dimensional effects and non-linear response are a main concern in the field of earthquake research and regulation. In the last decade, several experimental tests have been performed on reinforcedconcrete structures under seismic excitations (i.e. “CAMUS” program), in order to study the seismic behaviour of shear walls, but without significant 3D effects. The recent evolution of the different codes and the new French zoning map had emphasized the importance to better understand the capacity of irregular structure under seismic loadings.
Ultimate method of design was introduced in the early sixties of last century. Research work on the ultimate flexural capacity of a section was successfully completed with in few years. To predict the flexural capacity, equations were developed, whose results were in good agreement with the actual/experimental values. Mechanism of flexural failure of a rectangular reinforcedconcrete beam was much simpler to understand as compared to shear failure. In fact shear failure of reinforcedconcrete beams is a very complex phenomenon due to involvement of too many parameters. Factors influencing the shearcapacity of beams are shear span to depth ratio (a/d), tension steel ratio (ρ), compressive strength of Concrete (f c ΄),
According to the modelling result as explained in the above topics, the numerical simulation by using ABAQUS software could produce the result as closed as an experimental result. The non-linear material models which are available in the ABAQUS/Explicit material library such as Drucker-Prager and Cap-Plasticity that represent Ductile behavior give better and realistic results than the Brittle-Cracking model (Damage Concrete Plasticity). Furthermore, finite element analysis by using ABAQUS software is capable of developing reasonable and realistic estimations available in order to investigate the possible damage modes of reinforcedconcrete slabs under impact loads.
The benchmark CASH, organized by OCED-NEA, will gather international engineers and researchers on common exercises consisting of studying reinforcedconcreteshear wall capacity. The present article presents the first exercise proposed to the participants, base on the SAFE experimental tests. Four shear walls of entire programme have been selected for the purpose of this benchmark. Each participating team is invited to produce their best estimate calculation to evaluate the response of the specimens under static (monotonic and cyclic) and dynamic loading. The comparison of the modelling methods and the results of the participants will be released in November 2015 at the occasion of a workshop that will be held in Paris. The conclusions will be used for the second phase of the benchmark, where a full-scale shear wall of an NPP building will be studied.
Abstract: For shear-critical structural elements where the use of stirrups is not desirable, such as slabs or beams with reinforcement congestion, steel fibers can be used as shear reinforcement. The contribution of the steel fibers to the shearcapacity lies in the action of the steel fibers bridging the shear crack, which increases the shearcapacity and prevents a brittle failure mode. This study evaluates the effect of the amount of fibers in a concrete mix on the shearcapacity of steel fiber reinforcedconcrete beams with mild steel tension reinforcement and without stirrups. For this purpose, twelve beams were tested. Five different fiber volume fractions were studied: 0.0%, 0.3%, 0.6%, 0.9%, and 1.2%. For each different steel fiber concrete mix, the concrete compressive strength was determined on cylinders and the tensile strength was determined in a flexural test on beam specimens. Additionally, the influence of fibers on the shearcapacity is analyzed based on results reported in the literature, as well as based on the expressions derived for estimating the shearcapacity of steel fiber reinforcedconcrete beams. The outcome of these experiments is that a fiber percentage of 1.2% or fiber factor of 0.96 can be used to replace minimum stirrups according to ACI 318-14 and a 0.6% fiber volume fraction or fiber factor of 0.48 to replace minimum stirrups according to Eurocode 2. A fiber percentage of 1.2% or fiber factor of 0.96 was observed to change the failure mode from shear failure to flexural failure. The results of this presented study support the inclusion of provisions for steel fiber reinforcedconcrete in building codes and provides recommendations for inclusion in ACI 318-14 and Eurocode 2, so that a wider adoption of steel fiber reinforcedconcrete can be achieved in the construction industry.
36 deflection response from the experimental observation. In general, all five slab specimens that were modeled showed a very strong correlation between the finite element model and the experimentalresults (Figure 2-16). The ascending branch followed a very similar line as the experimental data and then, at the point of punching shear, the FEA curve experienced a very sharp downward trend. The two experiments (N-GR-C slab and L-SH-C slab) shown in Figure 2-16 have concrete compressive strengths that varies from 34 MPa to 47 MPa and a flexural reinforcement ratio, ρ, which varies from 0.24% to 0.15%. In developing the tension-stiffening curve the author only describes selecting 0.4 for the weakening function (see Equation (2-18)), but neglected to disclose what effect of varying the weakening function would have on the load- deflection results. Even though the concrete strength and flexural reinforcement varied in the specimens, the weakening function remained constant. The constant value of the weakening function appears to suggest that it is independent of the value of 𝑓 𝑐 ′ and ρ. This assertion would be in contrast to the literature data which showed tension-stiffening increases with increases in 𝑓 𝑐 ′ and ρ.
For these panels, a more ductile response was again found when a 4 inch bedding strip height was used, with over 0.010 radians of shear strain experienced at failure compared to less than 0.006 radians for the ½ inch strip specimens. The shear load capacity was much greater for the C.2 and D.2 panels than their A.1 and B.1 counterparts, due to the more robust design of the embed connection. One particularly interesting observation to be made, however, is that the ultimate capacities remained relatively the same when the bedding strip height was reduced. This illustrated that the additional prying moment created from an increased connection eccentricity had little effect on the panel’s ultimate capacity. The slight variation in ultimate strength between strip heights was most likely due to the high variability of concrete tensile properties. Despite this minor difference, all panels tested well exceeded the expected design strength. The results of the PCP in-plane shear tests when considering ultimate load are summarized below in Table 4.2, while calculations used in determining the expected shearcapacity can be found in Appendix A.2.
ReinforcedConcrete (RC) deep beams are commonly used in structural design to transfer vertical loads when there is a vertical discontinuity in the load path. Due to their deep geometry, the force distribution within the RC deep beams is very different than the RC shallow beams. T here are some strut and tie model (STM) already been developed for RC deep beams. However, most of these models are developed for RC deep beams with the simply supported boundary condition, which do not apply for RC deep beams with the fix-ended condition. In this paper, five fixed-end RC deep beams have been tested experimentally which were subjected to monotonic and cyclic loads. Also, a simple ST M was proposed to simulate the load capacity and failure mode of fix -ended RC deep beams. T he proposed ST M has the main strut and sub struts to simulate the force distribution within the RC deep beams. T his ST M were verified using five fixed-end RC deep beams subjected to monotonic and cyclic loads and compared to the response of 31 additional independent experimental tests. T he result shows the newly proposed ST M can simulate the load capacity and failure mode of fix-ended RC deep beams very well.