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Showing 4 results for Seismic Design

Guray Arslan, Melih Hacisalihoglu, Muzaffer Balci, Muzaffer Borekci,
Volume 12, Issue 2 (6-2014)

The main cause of structural damage in buildings subjected to seismic actions is lateral drift. In almost all reinforced concrete (RC) structures, whether designed with walls or frames, it is likely to be the code drift limits that control the design drift. The design drift limits and their contribution to damage may be represented indirectly through the material strain limits. The aim of this study is to investigate the seismic design indicators of RC columns using finite element analyses (FEA). The results of FEA have been compared with the results of experimental studies selected from literature. It is observed that the lateral load-deflection curves of analyzed columns are in agreement with the experimental results. Based on these lateral load-deflection curves, the drift limits and the material strain limits, given by the codes as performance indicator, are compared. It is observed that the material strain limits are non-conservative as performance indicator of RC columns, compared to the drift limits.
Mohsen Shahrouzi, Amir Abbas Rahemi,
Volume 12, Issue 2 (6-2014)

Well-known seismic design codes have offered an alternative equivalent static procedure for practical purposes instead of verifying design trials with complicated step-y-step dynamic analyses. Such a pattern of base-shear distribution over the building height will enforce its special stiffness and strength distribution which is not necessarily best suited for seismic design. The present study, utilizes a hybrid optimization procedure to seek for the best stiffness distribution in moment-resistant building frames. Both continuous loading pattern and discrete sizing variables are treated as optimization design variables. The continuous part is sampled by Harmony Search algorithm while a variant of Ant Colony Optimization is utilized for the discrete part. Further search intensification is provided by Branch and Bound technique. In order to verify the design candidates, static, modal and time-history analyses are applied regarding the code-specific design spectra. Treating a number of building moment-frame examples, such a hyper optimization resulted in new lateral loading patterns different from that used in common code practice. It was verified that designing the moment frames due to the proposed loading pattern can result in more uniform story drifts. In addition, locations of the first failure of columns were transmitted to the upper/less-critical stories of the frame. This achievement is important to avoid progressive collapse under earthquake excitation.
S. N. Moghaddas Tafreshi, T. Nouri. A,
Volume 12, Issue 2 (4-2014)

This paper presents a simple solution based on the limit equilibrium of sliding soil wedge of reinforced backfill subjected to the horizontal acceleration in the framework of the pseudo-static method. In particular, contrary to most studies on the reinforced retaining wall, the solution proposed in this study, takes into account the effect of the uniform surcharge on the reinforced backfill soil and of its distance from the face of the wall. The results are investigated in dimensionless form of the maximum reinforcement required strength (Kmax), the dimension of the sliding wedge (Lc/H), and the factor of safety (FS). Compared to the reinforced backfill without surcharge, the presence of surcharge over the reinforced backfill and of its distance from the top of the backfill have significant effects on the stability of the system. For a fixed surcharge, a minimum distance of surcharge exists for which the presence of the surcharge does not affect the solution and the failure mechanism is that corresponding to the case of system with no surcharge. A detailed design example is included to illustrate usage of proposed procedures. Comparisons of the present results with available results show a favorable agreement.
Dr. Abazar Asghari, Mr. Behnam Azimi Zarnagh,
Volume 15, Issue 5 (7-2017)

For years, coupling shear walls have been used in  the mid to high-rise buildings as a part of lateral load- resisting system mostly, because of their ability to control the displacement of structures, Recently by changing the design codes from strength based design to performance based  design, nonlinear behavior of coupled walls became important for practical engineers, so that many researchers  are looking for ways to improve and also predict the behavior of coupled walls under severe earthquakes. This paper  presents  the results of   linear,  nonlinear static ( pushover)  and  nonlinear inelastic time-history analysis  of a 10-story  two- dimensional coupling shear wall (CSW) which is perforated with 3 different patterns which are taken from considering  the S22 stress of shell elements used for modeling shear walls,  nonlinear static analysis results confirm that perforation can increase the response modification  factor of coupled walls up to 33 percent and also the results of  linear analysis and design indicate that perforation can reduce the amount of reinforcement of coupling beams and other framechr('39')s  structural components. Also results of nonlinear inelastic time history  analysis confirm that by using perforation patterns the base shear- roof displacement hysteretic response get better and the  systems with perforation patterns can absorb more energy under severe earthquakes.

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