Experimental and Numerical Study on Ultimate Shear Load Carrying Capacity of Corroded RC Beams

For an RC beam, the strength of steel rebar, the bonding strength between the concrete and reinforcement, and the bite action between the aggregates will deteriorate significantly due to corrosion. In the present study, 10 RC beams were designed to study the impact of corrosion on the shear bearing capacity. The mechanism of corrosion for stirrups and longitudinal bars and their effects were analyzed. Based on the existing experimental data, the correlation between the stirrup corrosion factor and the cross section loss rate was obtained. An effective prediction formula on the shear bearing capacity of the corroded RC beams was proposed and validated by the experimental results. Moreover, a numerical analysis approach based on the FE technique was proposed for the prediction of the shear strength. The results show that corrosion of the reinforcements could reduce the shear strength of the RC beams. The corrosion of stirrups can be numerically simulated by the reduction of the cross section. The formulae in the literature are conservative and the predictions are very dispersed, while the predictions by the proposed formula agree very well with the experiment results.

Analysis of the Shear Capacity of Ultrahigh Performance Concrete Beams Based on the Modified Compression Field Theory

An analysis model of the shear capacity of prestressed ultrahigh performance concrete (UHPC) beams under the combined action of bending and shearing was established in this paper based on the modified compression field theory and by considering the unique material constitutive relation of UHPC. Shear tests were performed using three prestressed UHPC-T beams with different shear-span ratios to verify the correctness of the model. The results showed that the shear-span ratio greatly influenced the shear capacity and failure modes of UHPC-T beams. Upon increasing the shear-span ratio, the failure modes of the three beams were inclined compression failure, shear compression failure, and diagonal tension failure, successively. When the shear-span ratio changed from 1.04 to 2.12, the shear bearing capacity decreased greatly; however, when the shear-span ratio changed from 2.12 to 3.19, the decrease of the shear bearing capacity was very small. In addition, the MCFT analysis model was used to analyze the experimental data, and the predicted results were in good agreement, which proved the applicability of the model. Finally, according to the existing shear test results of UHPC beams and based on the main influencing factors, a simplified formula for predicting the shear capacity of UHPC beams was obtained by fitting. Comparing the MCFT model with the results of other pieces of literature, this formula accurately predicted the shear capacity of UHPC beams. The MCFT model and the simplified formula presented in this paper provide a powerful tool for predicting the shear performance of UHPC-T beams, which will contribute to the design and analysis of UHPC-T beams.

Experimental Study on an Innovative Shear Connector in Steel-UHPC Composite Structure

In order to improve the stiffness and shear bearing capacity of steel-UHPC composite bridge, an innovative shear connector named arc-shaped reinforcement shear connector was proposed and compared with the stud and perforated bar steel plate shear connector using the static push-out test. Considering shear connector diameter, a total of ten push-out specimens for five groups were designed. The results indicated that the failure modes and failure mechanism of the arc-shaped reinforcement shear connectors were significantly different from stud shear connector and perforated bar steel plate. Obvious failure characteristics such as crack and reinforcement were not observed for the arc-shaped reinforcement specimens except for fine cracks on the top of one specimen, but these were observed for the others two types of shear connector. The relative slip value of arc-shaped reinforcement shear connector at the maximum load was the smallest and less than 1 mm in three types of shear connectors. The stiffness and shear bearing capacity of arc-shaped reinforcement were higher than those of stud and perforated bar steel plate under the same diameter. Increasing arc-shaped reinforcement diameter could improve significantly static behavior of shear connector. When the diameter of arc-shape reinforcement was increased from 8 mm to 12 mm, the ductility factor, stiffness, and shear bearing capacity of arc-shaped reinforcement shear connector were improved by 174.32%, 214.76%, and 54.2%, respectively. A calculation method of shear bearing capacity was proposed by the least square method and multiple regression analysis and agreed well with the test result.

Experimental Study on the Influence of Second-Order Effect on Shear Bearing Capacity of Frame Columns with Cracks under Different Axial Compression Ratios

The construction joint is the weak part of the structure, and the P-δ effect is mostly ignored when considering the second-order effect, so it is necessary to study the influence of second-order effect on frame columns. Based on the above considerations, under different axial compression ratios, the mechanical properties of the construction joints of the frame columns with construction joints and the cast-in-situ frame columns were studied by low cycle repeated load testsand analyzed the influence of the second-order effect on the shear capacity of frame columns with joints. The test results indicate that the existence of construction joints reduces the shear-bearing capacity of the specimens, and the second-order effect has a greater impact on the columns with joints under the same axial compression ratio, and the shear capacity decreases more. With the increase of the axial compression ratio, the second-order effect will be weakened on the frame column with seam, but when the axial compression ratio exceeds a certain limit, the second-order effect will be increased.

Ultra high performance concrete shear walls

The history of the development of Ultra-High Performance Concrete (UHPC) shear walls and the current status of today’s research as well as the future development prospects are comprehensively collated. The analysis process and conclusive results of the present-day domestic and international research on UHPC shear walls are highlighted. The load displacement curves, hysteresis curves and skeleton lines of ultra-high performance concrete shear walls under different experimental loads are collated and compared. Integrate the corresponding equations for shear bearing capacity and equations for the overall specimen load displacement curves. A finite element model of the ultra-high performance concrete shear wall is established to simulate and perform non-linear finite element analysis of its force process under unidirectional horizontal loading.

Discussion on Calculation Method of Shear Bearing Capacity of HSC Beams Without Web Reinforcement under Concentrated Loads

In order to investigate the main influencing factors and development rules of the shear performance of high strength concrete (HSC) beams without web reinforcement under concentrated loads, analyze and compare the rationality of the China and American Code formulas and Zsutty formula, in this paper, 303 sets of experimental data about the shear test of HSC beams without web reinforcement at home and abroad were selected, based on these experimental data, the calculation method of the shear capacity of HSC beams without web reinforcement was discussed. The results showed that the measured shear bearing capacity of HSC beams without web reinforcement gradually increases with the decrease of the shear-span ratio. The nominal shear stress of HSC beams without web reinforcement gradually increases with the increase of concrete strength, the increase of longitudinal reinforcement ratio and the decrease of section height. The shear bearing capacity formula proposed by Zsutty is the most accurate prediction than other formulas. Based on the experimental data and considering the influence of the longitudinal reinforcement ratio on the shear bearing capacity of structure, a new calculation formula for the shear bearing capacity of HSC beams without web reinforcement under concentrated loads was obtained by regression analyze, and this formula is more comprehensive than the other three calculation formulas, moreover, the calculation results are more reasonable.

Seismic performance and shear bearing-capacity of truss SRC beam-column frame joints

The structural performance of a frame joint is particularly important, which can determine the safe state of the global structure. For this reason, the seismic performance of the truss steel reinforced concrete (SRC) beam-column frame joints is investigated by the experimental study and the nonlinear finite element modeling. The main design parameters include the section size of the web rods, the axial compression ratio and the section size of I-steel. The failure mechanism, load-displacement skeleton curve, the ductility and energy dissipation capacity, and shear deformation in the core zone of the truss SRC beam-column joints are studied. A formula is put forward to describe the shear bearing-capacity of the joints. The results indicate that the truss SRC beam-column frame joints generally have good seismic performance. The size of steel and web members have impact on the seismic performance of the truss SRC beam-column joints, and the axial compression ratio is an important factor that impacts the hysteresis behavior and energy dissipation. The proposed shear bearing-capacity formula can objectively reflect the performance of the joints.

Shear-bearing capacity analysis under static force for shear key of the reinforced concrete open-web sandwich slab applied to long-span structure

PurposeThe reinforced concrete open-web sandwich slab is composed of upper rib, lower rib, surface plate and shear key and was applied to long-span structure crossing at 18–30 m. The shear-bearing capacity of shear key, having vital effects on the slab’s bearing capacity, is analysed to present its calculation formula used for the engineering application of the slab.Design/methodology/approachThe shear-bearing capacity of shear key is analysed by the strut-and-tie model and the benchmark model established by the finite element method. Furthermore, the design formula of its shear capacity is given by the parametric analysis of FEM to adjust the result of the strut-and-tie model, using multivariate linear regression analysis of these parameters.FindingsThe calculation result of the benchmark model is compared with those of the strut-and-tie model and the standard formula, which indicates that the result of the strut-and-tie model is closer to that of the benchmark model than that of the standard formula. Moreover, the parametric analysis of the finite element model indicates that the volume–stirrup ratio of the shear key and the compression strength of the concrete have lesser effect on the shear capacity compared with the longitudinal reinforcement ratio and the shear-to-span ratio of the shear key and the relative section height of the rib.Originality/valueThe shear capacity of the shear key is provided in the paper by combining the finite element method and the strut-and-tie model, which is different from the calculation of the shear key in local codes and Chinese code, based on the theory of short corbel and the experiment of member. Furthermore, the formula of the shear capacity could be employed in the design and construction of the RC open-web sandwich slab, mainly used in the public and industrial multi-story building with long span to save the dwindling land resource currently.