The shear performance of concrete beams is known to be an important mechanical feature; hence, enhanced shear resistance is critical for determining a beam’s performance in terms of security and service life. This paper presents a study on the shear behavior of concrete beams without web reinforcement strengthened by external vertical prestressing rebars (EVPRs). Experimental data were obtained from seven test beams with varying influencing factors (stirrup ratio ρ_sEP, arrangement spacing s, prestressing force F_p, and compressive stress degree γ_p of the EVPRs) to determine their effects on the shear behavior. The results reveal that the EVPRs can significantly improve the shear capacity and ductility of concrete beams without web reinforcement. Furthermore, the failure mode is changed from brittle diagonal tension to relatively ductile shear compression, and the flexural cracks and shear cracks are more fully developed. The shear capacity becomes enhanced as the ρ_sEP and γ_p are increased; vertical compressive stress provided by the EVPRs can reduce the principal tensile stress of the concrete structure to prevent the shear cracking and enhance the shear resistance of the concrete. Meanwhile, in the stage from the formation of the critical shear crack (CSC) to the shear failure, the EVPRs can be used as stirrups to share the shear load. It can be concluded that EVPRs can effectively improve the shear performance of concrete beams.

The ultimate load capacities of steel fiber–reinforced concrete beams were determined by experiments conducted on steel fiber–reinforced concrete beams under the action of a two-point symmetrical concentrated load. Accordingly, failure modes and experimental data were obtained for 19 sets of test beams with varying concrete strength, longitudinal reinforcing bars, shear span ratio, and steel fiber volume content to determine their effects on steel fiber–reinforced concrete beam behavior. An optimization model reflecting the contributions of all tested factors to the shear capacity of a steel fiber–reinforced concrete beam is then derived and its accuracy is demonstrated by a comparison against the test results.

In order to analyze the causes of cracking in abutments subject to concrete shrinkage and temperature variation during the construction process and to determine factors affecting the mechanical properties of the abutment, nonlinear calculations capturing abutment behavior are conducted with Midas/FEA software. Using these calculations, the cracking mechanism is identified, and the influence of the evaluated factors is analyzed. It is concluded that the deformation between the pile cap and abutment backwall as constrained by a pile foundation when subjected to concrete shrinkage and temperature changes is the basic cause of abutment cracks during construction; these cracks form over the piles and develop upward. For a given reinforcement ratio, the distribution of horizontal crack‐control steel using small, closely spaced bars is more beneficial. When pile‐bearing capacity meets the standard, the width of the generated cracks tends to decrease with the decrease in the diameter of the piles. The existence of a postcast strip in the abutment backwall also contributes to the decrease in the depth of the crack. Finally, the impact of age difference between the pile cap concrete and abutment backwall concrete on cracking is inconsequential.

External vertical prestressing rebars (EVPRs) can effectively improve shear strength of concrete structures by the way of providing vertical compressive stress to the concrete and acting as stirrups. The objective of this study is to obtain a shear strength prediction model of EVPRs strengthening concrete beam without transverse reinforcement enhanced by modifying the ACI-318 and Critical Shear Crack Theory (CSCT). At the same time, this article analyzes the contribution of the strength of the shear strength, including the EVPRs as stirrups, compression zone of concrete, dowelling action, aggregate interlock and residual tensile strength. The results indicate that the shear strength prediction model can fit well with the experimental data and EVPRs can effectively enhance shear strength.

A finite segment method is presented to analyze the mechanical behavior of skewed box girders. By modeling the top and bottom plates of the segments with skew plate beam element under an inclined coordinate system and the webs with normal plate beam element, a spatial elastic displacement model for skewed box girder is constructed, which can satisfy the compatibility condition at the corners of the cross section for box girders. The formulation of the finite segment is developed based on the variational principle. The major advantage of the proposed approach, in comparison with the finite element method, is that it can simplify a three-dimensional structure into a one-dimensional structure for structural analysis, which results in significant saving in computational times. At last, the accuracy and efficiency of the proposed finite segment method are verified by a model test.