Currently, the steel plate shear wall (SPSW) is commonly used in high-rise steel buildings as a lateral load-resisting system due to its several advantages such as its lightweight and high ductility and strength. The SPSW consists of two main parts, i.e., the boundary frame and infill plate, which are connected by welding. The objective of this work is to study the effect of the infill plate weld separation on the seismic behavior of the SPSWs. A numerical method was proposed to have a comprehensive comparison of seismic behaviors of different separation characteristics. The model was validated by using previously published experimental works. Key parameters, such as load-carrying capacity, stiffness, and energy-dissipation capacity, were discussed extensively. The unstiffened SPSW (USPSW) system is more sensitive to the plate–beam separation than the plate–column one, especially the corner plate–beam separation. When plate–column welding separation occurs, the initial stiffness and the energy dissipation capacity are reduced by approximately 21% and 14%, respectively; however, the reductions are 36% and 20.5% in the case of beam welding separation.

The steel plate shear walls (SPSW) are currently being considered as a lateral load resisting system. A numerical method was proposed to have a comprehensive comparison of seismic behaviors of the plane wall (PW) and stiffened plane wall (SPW) with different stiffener characteristics, having the same weight, by using finite element modeling (FEM). The model was validated by using previously published experimental works. The material and geometric nonlinearity were taken into consideration. In this paper, the effect of using stiffeners with different cross-section shapes and directions will be studied, and key issues, such as load-carrying capacity, stiffness, and energy dissipation capacity, were discussed in depth. It was found that the proposed SPW with horizontal L, T, and U stiffeners could effectively improve load-carrying capacity by about 4, 20, and 23%, respectively. Diagonally and horizontally, SPWs with U stiffeners have higher energy-dissipation capacity than PW by about 57, 50%, respectively. This method provides a combination of high-performance stiffeners form and material for improving the seismic behavior of SPW.

This paper performs a simultaneous cross-sections and semi-rigid connections optimization for plane steel frames with semi-rigid beam-to-column connections, in company with fixed, semi-rigid and hinged base connections using, for the first time, a bees algorithm (BA), along with a genetic algorithm (GA). Both of algorithms are applied using Shallan et al. [1]optimization model. In this paper, the truthful Kanvinde and Grilli[2]nonlinear model is used for simulating semi-rigid base connections, where this model considers all deformations in different base connection elements under the applied loads to determine the relative spring rotation θ r for the sake of getting accurate base rotational stiffness value. In addition, Frye and Morris [3]nonlinear model is used for simulating semi-rigid beam-to-column connections. The P-∆ effect and geometric nonlinearity are considered. The stress and displacement constraints of AISC-LRFD [4] specifications, alongside size adjustment constraints, are considered in the design process.

In this research, analytical fragility curves for three existing structures are presented. Structures are 2-story, 6-story and 10-story residential reinforced concrete structures designed under dead ,live and seismic loads of zone 3 according to Egyptian code (2008). The design acceleration is 0.15g. The fragility curves are developed based on nonlinear incremental dynamic analysis of three dimensional structural models using SeismoStruct under twelve historic ground motions. Four performance levels are considered; fully operational, operational, life safe and near collapse.

Having the advantages of high quality and lower amount of materials for hollow core slabs (HCS), the extrusion method is not without its drawbacks because it does not allow shear reinforcement incorporation. However, the strength of HCS against shear stresses is withstood by concrete section only and shear failure of hollow core slab occurs suddenly without large deformation. Therefore, the question is what are the structural benefits of HCS that can be attained by adding shear reinforcements?. This paper is concerned with studying the effect of the presence of shear reinforcements on enhancing the structural behavior of the HCS. An experimental study was carried out on 5 full-scale precast pre-stressed modified hollow core slabs specimens (MHCS) subjected to shear loads. Each MHCS panel is comprised of longitudinal, transverse ribs and lower thin slab layer. The spaces between the ribs and the lower concrete layer are filled with polystyrene foam blocks. The results of two specimens were compared with that obtained from a hollow core slab panel having the same dimensions, pre-stressed reinforcement concrete grade and loading scheme. Results indicated that the ultimate shear capacity, failure modes, and load deflection relationships of the proposed slabs are greatly improved by using the suggested technique.