This paper includes the investigation of the soil–structure interaction (SSI) effect on the seismic response of 20 and 30-story reinforced concrete moment resisting frames (MRFs) rested on a piled raft foundation using the direct approach. After that, a study is conducted to show the impact of using a cellular raft instead of the designed solid raft on the dynamic response of the building. A study is introduced to select the best gap size for the cellular raft. The soil model is assumed as a single layer of sandy clay. Time history analysis by the direct integration method is performed under seven earthquake records (El-Centro, Northridge, Kobe, Chichi, Friuli, Kocaeli, and Loma), which are scaled to the Egyptian Code for Loads (ECP-201) response spectrum using a full 3D model by a finite element software named (Midas GTS NX). It is concluded that considering SSI significantly affects the dynamic response of high-rise buildings, and using cellular rafts generally leads to a decrease in their dynamic response.

This study includes an investigation of using a cellular raft over piles on the seismic response of both a twisting and regular tower using the direct method, demonstrating the variance between a solid raft and a cellular raft. Both towers are 52 stories high and made of reinforced concrete. They were also built on a reinforced concrete piled-raft foundation. The soil model is thought to be multi-layered and has the same profile as the zone under investigation (New Mansoura, Egypt). All structural properties (dimensions, section properties, materials) are equal to allow a fair comparison of output response for both towers. The sole difference between the two towers is their elevation. The study is carried out under seismic loads using nonlinear time-history analysis. All analyses are carried out employing finite-element software (Midas GTS NX). Thus, seven distinct earthquake records with full 3D models were used for time-history research. According to the findings and discussions, it is concluded that adopting a cellular raft can reduce the dynamic response of the towers. Considering the soil–structure interaction, the maximum inter-story drift ratio decreases by 8.17% for the twisting tower and 5.58% for the regular tower while using the cellular raft. Furthermore, the regular tower is more effective than the twisting tower at resisting lateral loads.

This paper presents the study of traffic load variations effect on the dynamic analysis of cable-stayed bridges. Time histories of displacement, velocity, acceleration, normal force, and bending moment are presented for different traffic load speeds. This study is concerned with harp bridges having five spans considering single plane of cables with 140 m for exterior spans, and 280 m for interior spans. The total length of the bridge is 1120 m. The own weight of all structural elements, and traffic load including impact are taken into account. In the dynamic analysis, the energy method, based on the minimization of the total potential energy (TPE) of structural elements, via conjugate gradient technique is used. The procedure is carried out using the iterative steps to acquire the final configuration. All prepared computer programs in FORTRAN language for this work and their verification is written by [1]. The conclusion, which have been drawn from the present work are outlined.