Sharif Digital Repository

When the stiffness of a story is much less than the story above it, a significant portion of lateral displacement of the building is concentrated in this story and soft story is formed. One of the main reasons of soft story in buildings is eliminating or reducing the infill walls in lower stories. This reason is more important than the others because structural engineers usually neglect infill walls in modeling the structure, and on the other hand, architects do not consider the seismic behavior of infill walls during architectural design. In this research, based on the provision of soft story in seismic codes, 2277 macro models with different arrangements of infill walls in the adjacent... 

Numerous buildings have been damaged or destroyed in previous earthquakes by developing soft storey. Almost all the seismic codes have provisions to prevent soft storey in structures, most of them have recommended the ratio of stiffness between adjacent storeys, but none of them has proposed the method to calculate the storey stiffness. On the other hand a great number of previous researches on stiffness have been focused on approximate methods and accurate methods by using analytical softwares have been almost neglected. In this study, six accurate methods for calculating the storey stiffness have been studied on 246 two-bay reinforced concrete frames. It is shown with the results of the... 

A significant part of torsional effects in buildings is due to disregarding the arrangement of infill walls during the design. This is a challenging issue since on the one hand the structural engineers do not usually consider infill walls in modeling a structure, while on the other hand the architects do not pay attention to the seismic behavior of infill walls during architectural design. In this research, an approximate method for identifying the torsion caused by infill walls was proposed to be used at the final stages of basic architectural design, which is based on the geometric specifications of architectural plans and does not require structural specifications. For this purpose,... 

Torsion is one of the most important causes of building collapse during earthquakes. Sometimes, despite the symmetric form of the building, infill walls disturb the symmetry of the lateral resisting system. The purpose of this research is to investigate the effect of urban layout on developing torsion caused by infill walls. For this purpose, a typological study was conducted based on the conditions of perimeter walls on 364 buildings and then 9 cases were selected. The dimensions of the selected buildings are constant and the conditions of the perimeter walls including facades with openings and cantilevered facades are variable. The selected buildings with 60 different layouts of infill... 

Structures with inappropriate distributions of strength and stiffness have performed poorly in recent earthquakes, and most of the observed collapses have been related to some extent to configuration problems or a wrong conceptual design. Shear building models of multi-story structures are considered in this study and are subjected to a group of severe earthquakes. It is shown that the strength distribution patterns suggested by the seismic codes do not lead to a uniform distribution and minimum amount of ductility, drift, and damage. A new pattern is proposed that is a function of the period of the structure and the target ductility. An iterative approach is also developed to determine the... 

An effective procedure to incorporate kinematic interaction (KI) aspects in seismic analysis of soil-structures systems was presented. In this regard, first, the effect of KI on the structural response was investigated with special focus on the role of rocking component of foundation input motion (FIM). This was performed parametrically for a wide range of selected nondimensional parameters, which well define the introduced simplified soil-structure model. It was observed that ignoring the effect of rocking input motion may introduce errors, which can be on the unsafe side especially for slender structures with large embedment ratios. On the other hand, it was known that introducing the... 

This paper addresses the behavior of confined masonry walls with dominating shear failure mode in walls. For this purpose, failure modes of these walls are classified in details. For each failure mode, complete set of analytical-based relations for deriving parameters related to backbone curves is introduced. Calibrated finite element analyses are utilized as a benchmark for verification of some of the assumptions. The results of the proposed relations are compared with those of several Iranian and non-Iranian experimental data. Sensitivity analysis is performed in order to understand the effects of important behavioral characteristics of these walls. The results of this study indicate that... 

In many countries, there are traditional houses made of stone, adobe and brick, which perform relatively weakly in earthquakes. To mitigate casualties in future earthquakes, it is necessary to evaluate the current status of these buildings and propose effective methods to retrofit them. One method of evaluating the performance of buildings in earthquakes is through the use of fragility curves. These diagrams show the probability of exceeding a specific state of damage versus seismic intensity parameters, such as PGA, MMI, la, CAV etc. Fragility curves will provide an important basis for analytical methods, based on probabilistic approaches. Much work has been done on bridges, concrete and... 

It has been known for many years that the type of soil under structures affects the structural performance during earthquakes. In fact, the soil affects the structural response in two ways, through the change in the free-field motion (usually known as the site effect) and due to Soil- Structure Interaction (SSI). The site effect has been included in the seismic codes from the most beginning. However, the SSI effect had not attracted much attention. The most significant intervention in this regard has been the 1978 inclusion of SSI in the tentative provisions of ATC3-06 in the United States, which is based on the results of studies on elastic response of soil structure systems. The effect of...