On the Behavior of Coupled Shear Walls: Numerical Assessment of Reinforced Concrete Coupling Beam Parameters

Modern construction of high-rise and tall buildings depends on coupled shear walls system to resist the lateral loads induced by wind and earthquake hazards. The lateral behavior of this system depends on the structural behavior of its components including coupling beams and shear walls. Although many research studies in the literature investigated coupling beams and shear walls, these studies stopped short of investigating the coupled shear walls as a system. Therefore, in this research, the effect of the coupling beam parameters on the nonlinear behavior of the coupled shear walls system was investigated. The full behavior of a 10-story coupled shear wall system was modeled using a series of finite element analyses. The analysis comprised of testing several coupling beam parameters to capture the effect of each parameter on system response including load-deflection behavior, coupling ratio, crack pattern, and failure mechanism. The results indicated that a span-to-depth ratio equal to two is a turning point for the coupling beam behavior. Specifically, the behavior is dominated by ordinary flexure for a ratio of more than two and deep beam behavior for a ratio of less than two. This study showed that the coupling beam width does not have a significant effect on the coupled shear wall response. Additionally, it was concluded that the excessive coupling beam diagonal reinforcement could significantly affect the coupled shear walls behavior and therefore an upper limit for the diagonal reinforcement was provided. Moreover, limitations on the longitudinal and diagonal reinforcement and stirrups are presented herein. The analysis results presented in this paper can provide guidance for practitioners in terms of making decisions about the coupling ratio of the coupled shear walls.

Innovative methods of strengthening reinforced concrete structures

The article considers some of the most innovative methods of reinforced concrete compressed elements: strengthening of elements with the help of pre-compressed longitudinal reinforcing elements, strengthening by means of concrete padding device, of low strength concrete, to strengthen the elements by biaxial transverse compression of concrete and method is to strengthen the elements with a pre-stretched diagonal reinforcement. The test results on deformation and rigidity of compressed reinforced concrete pillars are given. For each variant of rack reinforcement, depending on their flexibility and the relative eccentricity of the external force, the most technologically and economically feasible method of amplification is proposed.

Diagonal reinforcement as strengthening to increase the stiffness and strength of concrete frame

Two test objects of concrete frame behavior against lateral loading were performed by applying structural analysis with the wall as diagonal reinforcement in modeling. The results of the structural analysis indicated that concrete frames with walls have better performance than concrete frames without walls. Twelve objects consisting of the frame without the wall, frame with the wall, and frames with a group of steel and bamboo as diagonal reinforcement at brick walls and concrete panel walls were tested at the laboratory with monotonic lateral forces that work parallel to the wall as the illustration of earthquake loads. The diagonal reinforcement elements can spread the force received by the wall and increase the strength of the wall as well as enhance the stiffness of the structural system at once. Bracing contributes to increasing the strength, especially in resisting the compressive forces due to the earthquake loads. Deformation occurs in the opposite direction between compression path and tension path at the diagonal area. The failure in the concrete frame can be caused by the in-plane force parallel to the wall. Bamboo is quite effective to be used as a substitute for steel reinforcement as bracing material despite its shortage of steel quality.