Formula For Shear Capacity Research Articles

The direct shear behavior of the ultra-high performance concrete-filled socket connections between the bridge piers and footings

Ultra-high performance concrete (UHPC)-filled socket connections (UFSCs) provide a novel method for connecting bridge piers and footings, and allow for high matching tolerance and accelerated construction. At present, the lack of related research on the direct shear behavior of UFSCs hindered the promotion of this technology. This paper carried out the push-out test to explore the influences of embedded depths, horizontal confining pressures, and the shear key shapes on the direct shear behavior of the UFSCs. Monolithic specimens were also tested as a reference. The experimental results showed that increasing the socket depth and horizontal confining pressure has a positive impact on the direct shear capacity. With the same key width, escalating the key root height could also enhance the direct shear capacity. The experimental results also indicated that the load-bearing capacity of UHPC-connected specimens was generally lower than those of corresponding monolithic specimens. AASHTO and JSCE formulas were used to predict the direct shear capacity of joints, which relatively underestimated the experimental results. The average ratio between the calculated values of the two formulas and experimental results was 0.70 and 0.81, respectively. Based on the strut-and-tie model (STM), the shear capacity formula for UFSC was proposed, exhibiting a high degree of agreement with the test results, with an average ratio between calculated values and experimental results of 0.98.

Experimental and numerical analysis on shear capacity of steel-reinforced geopolymer concrete beams with different shear span ratios

PurposeThe purpose of this study is to use the corrected stress field theory to derive the shear capacity of geopolymer concrete beams (GPC) and consider the shear-span ratio as a major factor affecting the shear capacity. This research aims to provide guidance for studying the shear capacity of GPC and to observe how the failure modes of beams change with the variation of the shear-span ratio, thereby discovering underlying patterns.Design/methodology/approachThree test beams with shear span ratios of 1.5, 2.0 and 2.5 are investigated in this paper. For GPC beams with shear-span ratios of 1.5, 2.0 and 2.5, ultimate capacities are 337kN, 235kN and 195kN, respectively. Transitioning from 1.5 to 2.0 results in a 30% decrease in capacity, a reduction of 102kN. Moving from 2.0 to 2.5 sees a 17% decrease, with a loss of 40KN in capacity. A shear capacity formula, derived from modified compression field theory and considering concrete shear strength, stirrups and aggregate interlocking force, was validated through finite element modeling. Additionally, models with shear ratios of 1 and 3 were created to observe crack propagation patterns.FindingsFor GPC beams with shear-span ratios of 1.5, 2.0 and 2.5, ultimate capacities of 337KN, 235KN and 195KN are achieved, respectively. A reduction in capacity of 102KN occurs when transitioning from 1.5 to 2.0 and a decrease of 40KN is observed when moving from 2.0 to 2.5. The average test-to-theory ratio, at 1.015 with a variance of 0.001, demonstrates strong agreement. ABAQUS models beams with ratios ranging from 1.0 to 3.0, revealing crack trends indicative of reduced crack angles with higher ratios. The failure mode observed in the models aligns with experimental results.Originality/valueThis article provides a reference for the shear bearing capacity formula of geopolymer reinforced concrete (GRC) beams, addressing the limited research in this area. Additionally, an exponential model incorporating the shear-span ratio as a variable was employed to calculate the shear capacity, based on previous studies. Moreover, the analysis of shear capacity results integrated literature from prior research. By fitting previous experimental data to the proposed formula, the accuracy of this study's derived formula was further validated, with theoretical values aligning well with experimental results. Additionally, guidance is offered for utilizing ABAQUS in simulating the failure process of GRC beams.

Shear properties of composite steel plate connectors for prefabricated steel–concrete composite beams

As a critical component of prefabricated steel–concrete composite beams, ideal connectors can ensure the mechanical properties of bridges and significantly improve the efficiency of assembly construction. CSPC connector (Composite steel plate connector) with excellent load-slip curve and assembly construction efficiency was designed to realize fast and simple assembly construction. CSPC connectors require prefabricated bridge deck with no holes and low installation accuracy requirements. The results of 6 push-out specimens and 12 finite element models show that the CSPC connector exhibits an excellent load-slip curve compared to the existing connectors, and its shear stiffness and ductility coefficient are 1.03 and 1.51 times that of the stud connector, respectively. The shear stiffness and shear capacity of CSPC connectors are 0.79 times and 0.96 times the original when the grouting material age is reduced from 28 days to 3 days due to the rapid construction demand. The weakening of shear capacity is not obvious. The shear capacity of the CSPC connector comes from the connection between high-strength bolts and composite steel plates. The pressure-bearing effect of grouting material is crucial in connecting composite steel plates. Meanwhile, the composite steel plate of CSPC connector should be designed with equal thickness, a height of 30 mm and a spacing of no more than 10 mm. The recommended ratio of high-strength bolt diameter to composite steel plate thickness is 1.25. Finally, fit the load-slip relationship of CSPC connector, and propose a shear capacity formula with a deviation of less than 12 % from the test results.

Seismic behavior of wall-type spiral stirrups-confined RC column to steel beam joint

This study proposes a new interior diaphragm joint between wall-type reinforced concrete column with high-strength spiral stirrups and steel beams, and the quasi-static test was conducted to investigate the seismic performance of the new joint under cyclic lateral force. Finite element model (FEM) simulation was carried out using the software ABAQUS, and the correctness of the FEM was verified by the results of the test. Additionally, the effect of parameters including the strength of concrete, thickness of the beam flange, interior diaphragm, joint flange, and joint web on the seismic performances of the joint was analyzed. Based on the parametric analysis and existing codes, a shear capacity formula was determined with the consideration of the shear capacity of the joint web and flange, and concrete. The comparison between the calculated and FEM results indicates that this formula could be regarded as an accurate calculation method for the shear-bearing capacity of different joint types in engineering design.

Study on Seismic Performance of Cold-Formed Thin-Walled Steel-Straw Board Composite Wall with Diagonal Brace

The composite wall studied in this paper is based on the original cold-fonned thin-walled steel-straw board composite wall, which is set up with inclined braces and rigid inclined braces to improve its seismic performance. The factors of aspect ratio are analyzed, and the formula of shear bearing capacity of composite wall is deduced. The results show that: (1) When the height-width ratio of the composite wall is 2.4m×1.2m, 1.8m×1.2m and 1.2m×1.2m respectively, the yield strength of the composite wall is 35.78kN, 37.47kN and 54.23kN respectively. The yield strength of the former increases by 4.72 %, and the yield str ength of the latter increases by 44.73 %. (2) Using the effective strip method, the error of the derived shear capacity formula is not large, and the difference between the experimental value and the simulated value is not large, in order to provide some reference for the seismic design of this kind of cold-fonned thin-walled steel-strawboard composite wall with diagonal brace.

Single keyed joints behaviour and capacity formulation under direct shear using non-linear finite-element analysis

Short precast box girders offer economical, safe, and serviceable structures that can be rapidly constructed. The joints between segments along the bridge span are considered locations of discontinuity that control its strength and behavior. This research aims to study the effect of lateral confinement and concrete compressive strength on the behavior of the dry single-keyed joint in precast segmental bridges under direct static shear caused by vertical load through non-linear FEA simulation. A parametric study was carried out by establishing and validating a Finite Element Analysis model in ABAQUS based on the Concrete Damage Plasticity model. The keyed joints with various combinations of compressive concrete strengths ranging from 15 MPa to 50 MPa at 5 MPa increments and confinement pressure ranging from 0 to 6 MPa at 1 MPa increments were tested. The results of the numerical analysis of the 56 combinations were produced in the form of ultimate load-carrying capacity, load–displacement curves, crack evolution, and concrete crushing evolution in the keyed zone, leading to a better understanding of the behavior and failure sequence of the mentioned joints. The increase in lateral confinement led to increasing the ultimate shear strength of the keyed dry joint as well as increasing its initial stiffness and vertical displacement at the peak load consequently. However, this enhancement ceases with lower-grade concrete strength at higher confinement levels. A new shear capacity formula was proposed and evaluated against the numerical analysis results, selected experimental work, and the current design formulas, including AASHTO. The proposed formula was shown to agree very well with mentioned experimental and numerical work.

Influence of reinforcement parameters on punching shear capacity of laterally restrained FRP-reinforced concrete bridge deck slabs

Previous experimental and numerical research studies have investigated the behavior of laterally restrained FRP-reinforced concrete bridge deck slabs under wheel loading. Existing punching shear models are limited in their degree of accuracy due to the normalization approach and lack of consideration of all reinforcement parameters. This paper reiterates the established parameters (i.e., longitudinal and transverse bars’ spacing and size) and assesses their influence through a numerical study to develop an empirical formula for calculating the punching shear capacity. The results revealed that the bar spacing has more influence than the bar size on the punching shear capacity; thus, normalizing the reinforcement amount into the reinforcement ratio, ρ, is no longer valid. An empirical punching shear capacity formula is developed herein using data collected from three previous experimental studies. The rationality of the developed formula was examined and tested based on experimental and numerical models. Moreover, the results obtained by the developed formula were compared with available punching shear models, which testified about the accuracy and effectiveness of the developed formula.

INFLUENCE OF LONGITUDINAL REINFORCEMENT RATIO ON SHEAR CAPACITY OF NO COARSE-AGGREGATE CONCRETE

The study investigated the effect of longitudinal reinforcement ratio on the shear capacity of concrete beams without transverse steel. The concrete mixture did not include coarse aggregate. The Joint ACI–ASCE Committee 426 (1973) has shown that the shear is transferred across the surface where there is slip and it is called the aggregate interlock. To study the effect of longitudinal reinforcement ratio on the shear capacity of concrete without coarse aggregate, six beam specimens with the size of 110 × 7 × 12.5 cm and a/d ratio of 45/10.5 were investigated. The longitudinal reinforcement ratios were set from the minimum to the maximum, i.e. 0.0073, 0.0132, 0.0213, 0.0302, 0.0547, and 0.0782. The ratios of the ultimate shear to the shear capacity of concrete (Vu/Vc) were found between 1.0705 and 2.8748. When the longitudinal reinforcement ratio increases particularly from the minimum ratio, the value of Vu/Vc also significantly increases. The values of Vu/Vc were found less than 2, thus Vs is required. When the longitudinal reinforcement ratio approaches maximum, Vu/Vc becomes relatively constant and was found more than 2. This concludes that the ratio of Vu/Vc of the concrete without coarse aggregate is lower than normal concrete. The existing ACI’s formula for computing the shear capacity contributed by concrete, which has not been changed for decades, is only applicable for normal concrete (with coarse aggregate). This research proposes a theory to develop a new shear capacity formula specifically for concrete without coarse aggregate.

Mechanical properties of modular prefabricated steel-concrete composite internal joints under cyclic loading

To investigate the influence of the key parameters on the mechanical properties of modular prefabricated steel-concrete composite internal joint (MPCIJ), finite element model (FEM) of MPCIJ under cyclic load was established by using the finite element analysis (FEA) software ABAQUS, based on test results. FEA results were then compared with the test hysteresis curves, skeleton curves, and failure mode. Based on the verification of reliability of the numerical model, the influence of different parameters on the structural performance was analyzed. According to test and FEA results, the MPCIJ shear mechanism and bearing capacity calculation formula were proposed. Results showed that MPCIJ bearing capacity and deformation performance increased with increasing axial compression ratio (n < 0.45), however, the increase was within 5%. With the increase of concrete strength, the joint bearing capacity and fire resistance and corrosion resistance of joint modules were effectively improved. The recommended width/thickness ratio of the square steel tube should not be less than 17. Reducing the distance between the bolt edges could improve the plastic deformation of the joint module with the recommended value of 25–35 mm. The bolt hole diameter increase should be between 1.5 and 2 mm. MPCIJ bearing capacity increased with increasing thickness of joint cover plate and the peak load increased by about 17%; however, the shear deformation inside the joint module also increased. The shear mechanism of MPCIJ is the ‘steel plate shear wall’ and ‘T-shaped steel frame’. The correctness and reliability of the MPCIJ shear capacity formula were verified.

Study on the seismic performance of high-performance polypropylene fiber-reinforced lightweight aggregate concrete columns

Seven specimens of high-performance polypropylene fiber-reinforced lightweight aggregate concrete (HPPLWC) columns and three specimens of lightweight aggregate concrete (LWAC) columns were tested under low cycle reciprocating loading to study the seismic behavior of HPPLWC columns. The effects of axial compression ratio, stirrup ratio and high-performance polypropylene fiber (HPPF) content on the seismic behavior of LWC columns were studied. The effectiveness of HPPFs to supersede stirrups under earthquake was also discussed. Through the study of the failure phenomenon, hysteretic curve, ductility, energy dissipation, stiffness degradation, shear capacity, and other test results, it was found that: The additional HPPF could effectively inhibit the development of cracks and ameliorate the failure mode of specimens. The enhancement effect of HPPF on ductility and energy dissipation of specimens was much higher than that of increasing stirrup ratio. The calculated value of shear capacity formula given by NZS3101 in New Zealand was in good agreement with the experimental results, providing a reference for the supplement and perfection of the LWAC code formula. The low stirrup ratio HPPLWC specimens and the high stirrup ratio LWAC specimens were similar to the seismic performance. Therefore, HPPFs could effectively supersede some stirrups in the seismic application of complex structures.

Influencing Factors and Shear Capacity Formula of Single-Keyed Dry Joints in Segmental Precast Bridges under Direct Shear Loading

This article investigates the nonlinear behavior of single-keyed dry joints in segmental precast bridges under direct shear loading on the basis of nonlinear finite element analysis on lots of specimens with concrete plastic damage considered. Through detailed discussion on existing research, influence factors of the ultimate shear capacity of the keyed dry joint are analyzed, a new shear capacity formula was proposed and evaluated. The feasibility and correctness of the FE simulation method were verified by comparison with the existed experimental results. Concrete tensile strength at the key root is critical to the ultimate bearing capacity of the single-keyed dry joint under the direct shear loading. Friction on the joint interface and dimension parameters of the key do not have much effect on the ultimate shear capacity. However, reasonable key inclination (tanθ) would be suggested as 0.7~0.9. In comparison with the predicted results obtained by other existed formulas, the proposed formula is demonstrated to be in perfect consistency with both tests and the FE simulation results.

Shear capacity of sea sand concrete beams with polymer bars

Basalt-fibre-reinforced polymer bars (BFRPBs) can replace steel bars in sea sand concrete (SSC) structures to prevent the corrosion of steel by chloride ions and thus sea sand can be directly added to concrete materials used in construction. Shear tests on 16 SSC beams reinforced with BFRPBs (ten beams with stirrups and six beams without stirrups) were carried out and their failure modes, shear capacities and influencing factors were analysed. The results revealed two primary failure modes for SSC beams with BFRPBs: bending failure and shear-compression failure. Based on the existing shear capacity formula, a new formula for calculating the shear capacity of SSC beams reinforced with BFRPBs is presented by incorporating the effect of the shear span ratio. The results calculated using the proposed formula were consistent with the experimental results.

Punching shear behavior of recycled aggregate concrete slabs with and without steel fibres

A study on the punching shear behavior of 8 slabs with recycled aggregate concrete (RAC) was carried out. The two main factors considered were the recycled coarse aggregate (RCA) replacement percentage and the steel fibre volumetric ratio. The failure pattern, load-displacement curves, energy consumption, and the punching shear capacity of the slabs were intensively investigated. It was concluded that the punching shear capacity, ductility and energy consumption decreased with the increase of RCA replacement percentage. Research findings indicated that the incorporation of steel fibres could not only improve the energy dissipation capacity and the punching shear capacity of the slab, but also effectively improve the integrity of the slab tension surface and thereby changing the trend from typical punching failure pattern to bending-punching failure pattern. On the basis of the test, the punching shear capacity formula of RAC slabs with and without steel fibres was proposed and discussed.

Evaluation of Shear Strength of RC Beams Without Shear Reinforcement Using Modified Compression Field Theory

For reinforced concrete design and evaluation, the designer needs to compute the shear capacities for members based on their damage state. However, the most popular code-based shear capacity formula for RC frame members (ACI318-14) is not capable of providing such a required demand. Furthermore, for RC members with specific uncommon material properties or loading or very special detailing, code-based formula might not be applicable. The main objective of this paper is to highlight some of the shortcomings of current procedures for shear design of RC members and provide alternatives using finite element modeling. Hence, 120 shear critical rectangular beams without shear reinforcements are modeled through VecTor2 finite element program developed at the University of Toronto based on the modified compression field theory and the disturbed stress field model. The computed results are compared with published laboratory tests and ACI318-14 shear capacity estimations. The VecTor2 finite element simulations can predict the shear strength of reinforced concrete beams with an acceptable accuracy, while the ACI318-14 provisions provide imprecise estimate of shear capacity for some cases.

Method for computing the shear capacity of prestressed reinforced concrete beams based on truss-arch model

PurposeThe calculation of the shear capacity of inclined section for prestressed reinforced concrete beams is an important topic in the design of concrete members. The purpose of this paper, based on the truss-arch model, is to analyze the shear mechanism in prestressed reinforced concrete beams and establish the calculation formula for shear capacity.Design/methodology/approachConsidering the effect of the prestressed reinforcement axial force on the angle of the diagonal struts and regression coefficient of softening cocalculation of shear capacity is established. According to the shape of the cracks of prestressed reinforced concrete beams under shear compression failure, the tie-arch model for the calculation of shear capacity is established. Shear-failure-test beam results are collected to verify the established formula for shear bearing capacity.FindingsThrough theoretical analysis and experimental beam verification, it is confirmed in this study that the truss-arch model can be used to analyze the shear mechanism of prestressed reinforced concrete members accurately. The calculation formula for the angle of the diagonal struts chosen by considering the effect of prestress is accurate. The relationship between the softening coefficient of concrete and strength of concrete that is established is correct. Considering the effect of the destruction of beam shear plasticity of the concrete on the surface crack shape, the tie-arch model, which is established where the arch axis is parabolic, is applicable.Originality/valueThe formula for shear capacity of prestressed reinforced concrete beams based on this theoretical model can guarantee the effectiveness of the calculation results when the structural properties vary significantly. Engineers can calculate the parameters of prestressed reinforced concrete beams by using the shear capacity calculation formula proposed in this paper.

Investigation on Punching Shear Capacity of Hollow Slab-column Connection

To investigate the punching shear capacity of cast-in-situ reinforced concrete hollow slab-column connections under the unbalanced bending moments, a series of specimens were tested and analyzed in this paper. Hollow ratio, direction of moment, tube layout pattern and other factors are considered in the experiment. Performance of the specimens was evaluated in terms of cracking load, ultimate bearing capacity, fracture distribution and load-displacement curve. Moreover, the punching shear capacity formula of the hollow slab-column connections was provided. The experimental results show that the failure patterns of the specimens are punching failure; stiffness improved with the increase of thickness. Under one-direction unbalanced moment, the punching shear capacity decreases with the increase of hollow ratio; Under bi-direction unbalanced bending moment, the punching shear capacity increases with the increase in hollow ratio; the punching shear capacity is higher when bending moment along the tube compared to bending moment cross the tube, but it is not obvious; the specimens under bidirection unbalanced moment have lower punching shear capacity and better deformation ability compared with specimens under one-direction unbalanced moment. Using the proposed punching shear capacity formula, the calculated values are in good agreement with measurements.

Analytical deformation characteristics and shear capacity of SRC-RC transfer columns

In a steel reinforced concrete-reinforced concrete, SRC-RC, transfer column, the steel is truncated, and this leads to distortion of the internal force transmission. According to the internal force and deformation characteristics of transfer column, the location of the inflection point was studied. Then, the shear capacity of transfer column was investigated, and the results were compared with experimental results in references. The finite element model of SRC-RC transfer column was developed by ABAQUS, considering the effect of different confinement around concrete. The model has been validated against published experimental results. Finally, parametric studies were performed to evaluate the security and rationality of the shear capacity formula in Chinese code by FEM. The results indicated that the shear capacity calculated by the existing specification is unsafe, and a modified formula was proposed by considering the internal force and deformation characteristics of transfer column.

A simplified approach to assess the size effect on the shear-flexure interaction in RC elements

Following the concept of design capacity, the main purpose of the structural design of RC elements is to avoid brittle failures and to ensure ductile behavior. Under cyclic loading, the shear strength is reduced by increasing the flexural ductility. A good estimation of the failure mode of RC elements exhibiting a shear-flexural interaction relies on a good estimation of the flexural capacity (strength and ductility) and the shear capacity. In the present paper, a simplified model is proposed to describe the flexural behavior. The size effect is taken into account for the assessment of the flexural ductility. On the other hand, based on a comparative study of existing shear capacity models, a shear capacity formula is proposed to evaluate the shear strength and the shear reduction. The failure mode prediction is assessed following the ATC (Applied Technology Council) conceptual model. Comparison with experimental tests shows the ability of the proposed approach to predict the failure mode and the corresponding ductility.

Shear Capacity of Multiple Eco-Composite Wall

Multiple eco-composite wall is one of the most commonly used lateral-load resisting member in eco-composite wall structure. The main influencing factors of shear capacity for the wall are analyzed. Based on this, the shear capacity formula of multiple eco-composite wall is put forward and the application scope of the formula is discussed. In addition, a satisfactory agreement is obtained from the comparison between the values from the formula and experimental results. Theoretical research and test analysis show that the shear formula of multiple eco-composite wall is valuable for theoretical analysis and practical application.

Analysis of Shear Capacity of Stirrup Corroded RC Beam Based on the Truss-Arch Theory

On the basis of truss-and-arch model and the concrete softening strength criterion under ultimate state, a formula for shear capacity of reinforced concrete (RC) beam with diagonal reinforcement was established and verified. Accordingly, six RC beams with diagonal reinforcement and corroded stirrup were tested along with control group, the tested results were analyzed by liner regression to modify the formula given. Hence a formula for inclined section shear capacity of stirrups corroded RC beam with diagonal reinforcement was proposed and compared with a preceding formula without a consideration of diagonal reinforcement in corroded RC beam .The results showed that the existence of diagonal reinforcing steel bars enhanced the behavior of vertical compression web member in truss institutions, therefore increasing the shear force shared by truss mechanism. The inclination of diagonal web member is a crucial parameter of truss model. As the stirrup corrosion aggravating, the shear bearing capacity of such RC beams does not decrease drastically.