• Earthquakes and Structures
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• 제16권6호
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• pp.757-769
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• 2019

The seismic performance of a coupled shear wall system is governed by the shear resistances of its coupling beams. The plate-reinforced composite (PRC) coupling beam is a newly developed form of coupling beam that exhibits high deformation and energy dissipation capacities. In this study, the shear capacity of plate-reinforced composite coupling beams was investigated. The shear strengths of PRC coupling beams with low span-to-depth ratios were calculated using a softened strut-and-tie model. In addition, a shear mechanical model and calculating method were established in combination with a multi-strip model. Furthermore, a simplified formula was proposed to calculate the shear strengths of PRC coupling beams with low span-to-depth ratios. An analytical model was proposed based on the force mechanism of the composite coupling beam and was proven to exhibit adequate accuracy when compared with the available test results. The comparative results indicated that the new shear model exhibited more reasonable assessment accuracy and higher reliability. This method included a definite mechanical model and reasonably reflected the failure mechanisms of PRC coupling beams with low span-to-depth ratios not exceeding 2.5.

• Steel and Composite Structures
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• 제44권5호
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• pp.677-684
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• 2022

This paper reports experimental investigation on shear behavior of steel reinforced concrete (SRC) shallow floor beam, where the steel shape is embedded in concrete and the high strength bolts are used to transfer the shear force along the interface between the steel shape and concrete. Six specimens were conducted aiming to provide information on shear performance and explore the shear bearing capacity of SRC shallow floor beams. The effects of the height of concrete slab, the size and the type of the steel section on shear performance of beams were also analyzed in the test. Based on the strut-and-tie model, the shear strength of the SRC shallow floor beam was proposed. Experimental results showed that composite shallow floor beam exhibited satisfactory composite behavior and all of the specimen failed in shear failure. The shear bearing capacity increased with the increasing of height of concrete slab and the size of steel shape, and the bearing capacities of beam specimens with castellated steel shape was slightly lower than those of specimens with H-shaped steel section. Furthermore, the calculations for evaluating the shear bearing capacity of SRC shallow floor beam were verified to be reasonable.

• Structural Engineering and Mechanics
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• 제33권3호
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• pp.357-371
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• 2009

Test results of thirteen reinforced concrete corbels with shear span-to-depth ratio greater than unity are reported. The main variables studied were compressive strength of concrete, shear span-to-depth ratio and parameter of vertical stirrups. The test results indicate that the shear strengths of corbels increase with an increase in compressive strength of concrete and parameter of vertical stirrups. The shear strengths of corbels also increase with a decrease in shear span-to-depth ratio. The smaller the shear span-to-depth ratio of corbel, the larger the stiffness and the shear strength of corbel are. The higher the concrete strength of corbel, the higher the stiffness and the shear strength of corbel are. The larger the parameter of vertical stirrups, the larger the stiffness and the shear strength of corbel are. The softened strut-and-tie model for determining the shear strengths of reinforced concrete corbels is modified appropriately in this paper. The shear strengths predicted by the proposed model and the approach of ACI Code are compared with available test results. The comparison shows that the proposed model can predict more accurately the shear strengths of reinforced concrete corbels than the approach of ACI Code.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.918-923
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• 2003

Reinforced concrete deep beams are commonly used in many structural applications, including transfer girders, pile caps, foundation walls, and offshore structures. The existing design methods were developed and calibrated using normal strength concrete test results, and their applicability th HSC deep beams must be assessed. For the shear strength prediction of high-strength concrete(HSC) deep beams, this paper proposed Softened Strut-and-Tie Model(SSTM) considered HSC and bending moment effect. The shear strength predictions of the refined model, the formulas the ACI 318-02 Appendix A STM, and Eq. of ACI 318-99 11.8 are compared with the collected experimental data of 74 HSC deep beams with compressive strength in the range of 49-78MPa . It is shown the shear strength of deep beam calculated by those equations are conservative on comparing test results. The comparison shows that the performance of the proposed SSTM is better than the ACI Code approach for all the parameters under comparison. The parameters reviewed include concrete strength, the shear span-depth ratio, and the ratio of horizontal and vertical reinforcement. The proposed SSTM gave a mean predicted to experimental ratio of 0.99, 32 percent higher than ACI 318-02 Code, however with the low coefficient variation.

• Structural Engineering and Mechanics
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• 제5권6호
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• pp.803-815
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• 1997

It is well understood that concentrated forces applied in the plane of a beam or panel (such as a wall or slab) lead to splitting forces developing within a disturbed region forming beyond the bearing zone. In a linearly elastic material the length of the disturbed region is approximately equal to the depth of the member. In concrete structures, however, the length of the disturbed region is a function of the orthotropic properties of the concrete-steel composite. In the detailing of steel reinforcement within the disturbed regions two limit states must be satisfied; strength and serviceability (in this case the serviceability requirement being acceptable crack widths). If the design requires large redistribution of stresses, the member may perform poorly at service and/or overload. In this paper the results of a plane stress finite element investigation of concentrated loads on reinforced concrete panels are presented. Two cases are examined (i) panels loaded concentrically, and (ii) panels loaded eccentrically. The numerical investigation suggests that the bursting force distribution is substantially different from that calculated using elastic design methods currently used in some codes of practice. The optimum solution for a uniformly reinforced bursting region was found to be with the reinforcement distributed from approximately 0.2 times the effective depth of the member ($0.2D_e$) to between $1.2D_e$ and $1.6D_e$. Strut and tie models based on the finite element analyses are proposed herein.

• 복합신소재구조학회 논문집
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• 제4권2호
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• pp.8-14
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• 2013

Deep beam shall be designed either by taking into account nonlinear distribution of strain or by Appendix A of Strut-and-Tie Models (STM) according to ACI 318(M) from version of 2002. Although STM is accepted as tool in design Discontinuity region (D-region) which mostly exist in Deep beam, Corbels, Dapped ends etc., it has been modified by many researchers. In this study we design deep beam by STMs which use simple truss for load distribution and the model of complex truss for load distribution compare with the ACI traditional which is designed by flexure design method and shear provided by concrete($V_c$) as provided in special provisions section of 11.8 in ACI 318-99 [1]. This study aims to find the different and efficiency of deep beam design based on variation of parameter compiled from many samples selected from ACI traditional and two model of STMs, simple and complex load distribution.

• Advances in concrete construction
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• 제10권3호
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• pp.185-193
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• 2020

An analytical model is developed in this paper to predict the shear capacity of reinforced concrete (RC) columns with corroded transverse reinforcements. The shear strength model for corroded RC columns is proposed based on modifying the existing strut-and-tie model, which considers the deformational compatibility between truss and arch mechanisms. The contributions to the shear strength from both truss and arch mechanisms are incorporated in the proposed model. The effects of corrosion level of transverse reinforcements are considered in the proposed model through the minimum residual cross-sectional area of transverse reinforcements and the reduction of concrete compressive strength for the cover area. The shear strengths calculated from the developed model are compared with the experimental results from Vu's study (2017), which consisted of RC columns with corroded transverse reinforcements showing shear failure under the cyclic loading. The comparison results indicate satisfactory correlations. Parametric studies are conducted based on the developed shear strength model to explore the effects of column axial loading, aspect ratios, transverse reinforcements and the corrosion levels in transverse reinforcements to the shear strength of RC columns with corroded transverse reinforcements.

• Structural Engineering and Mechanics
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• 제10권6호
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• pp.589-601
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• 2000

A simplified analysis procedure utilizing the strut-tie modeling technique is developed to take a close look into the post-elastic deformation capacity of beam-column connections in ductile reinforced concrete frame structures. Particular emphasis is given to the effect of concrete strength decay and quantity and arrangement of joint shear steel. For this a fan-shaped crack pattern is postulated through the joints. A series of hypothetical rigid nodes are assumed through which struts, ties and boundaries are connected to each other. The equilibrium consideration enables all forces in struts, ties and boundaries to be related through the nodes. The boundary condition surrounding the joints is obtained by the mechanism analysis of the frame structures. In order to avoid a complexity from the indeterminacy of the truss model, it is assumed that all shear steel yielded. It is noted from the previous research that the capacity of struts is limited by the principal tensile strain of the joint panel for which the strain of the transverse diagonal is taken. The post-yield deformation of joint steel is taken to be the only source of the joint shear deformation beyond the elastic range. Both deformations are related by the energy consideration. The analysis is then performed by iteration for a given shear strain. The analysis results indicate that concentrating most of the joint steel near the center of the joint along with higher strength concrete may enhance the post-elastic joint performance.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.577-582
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• 2000

This study is aimed to evaluate the shear strength of reinforced concrete deep beams subject to concentrated loads, using a simplified strut-tie model. For the shear strength prediction of deep beams, it is prerequisite to evaluate the effective width of strut and to verify the efficiency factors proposed by MacGregor et al.. The results analyzed by truss models have been compared with those calculated by domestic code for the existing data of 90 deep beam specimens. The shear strength of deep beams were reviewed with respect to concrete strength, the shear span-depth ratio, and the ratio of web reinforcements. The results showed that the shear strength of the proposed model gave a better agreement than the domestic code approach.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.49-52
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• 2004

In this studies, Dapped End Beams(DEB) having disturbed regions were designed by using strut tie model, and the main purpose of this paper is that whether T-headed bars and Steel fibers will be present or not. The ability of DEB with T-headed bars have a superior performance rather than others, such as improved ductility, larger energy adsorption and enhanced post-peak load carrying capability. The capacity of DEB with steel fibers also show increase of ductility, shear strength, fatigue strength and crack. Each DEB with both headed bars and steel fibers, headed bars, and steel fibers as a substitute reinforced steel in the disturbed regions and a DEB with only stirrup and tie reinforced steel were comparable. In contrast, the headed bar stirrups, the tie headed bars and the reinforced steel fibers did not lose their anchorage and hence were able to develop strain hardening and also served to delay buckling of the flexural compression steel. Excellent load-deflection predictions were obtained by increasing the tension stiffening effect to account for high load effects.