Since the nonlinear static procedure (NSP) is one of the most prevalent and useful methods for the Performance-Based-Design (PBD) of buildings, it is considered by several researchers during past decades, so that the capability assessment of NSP in comparison with the nonlinear dynamic procedure (NDP) and improving the NSP accuracy are the basic subject of previous studies. Therefore, in this paper several load patterns used in conventional and advanced NSP such as displacement-based adaptive NSP (DAP) and multi-mode interaction adaptive NSP (APAM) are evaluated and the results are compared with NDP responses. Based on modeling assumptions the results demonstrate that the CPA with elastic load patterns cannot predict displacement and story drift for high-rise models. The maximum differences between CPA and APA is almost 7.9%. In addition, the DAP adaptive method presents an almost accurate prediction of SEISMIC DEMANDS and it can consider the effect of higher modes on inelastic responses. However, although the APAM adaptive method considers the interaction between modes, but it cannot predict the interstory drift angle at lower stories accurately. This behavior is intensified while the height of buildings increases.

Appropriate modeling of connections behavior is needed for SEISMIC evaluation of structures. However, large dispersion is observed in welded steel moment frame connections performance during recent earthquakes and experimental tests. In this study, the effect of dispersion in pre-Northridge connections characteristics is investigated. Two mid-rise steel moment frames are designated. Various types of fractures in beam-column connections with various configurations are modeled. Sensitivity study is carried out on parameters affecting the structural response for two probability levels by implementation of nonlinear dynamic analysis. Results show that variation in connection characteristics moderately affects the displacement DEMANDS of structures.

Observations from past earthquakes in reinforced concrete buildings show that the masonry partitions can endanger the life of buildings occupants and lead to significant damage and loss. The most present codes of practice do not consider the effects of nonlinearity and higher modes of the structure and three-dimensional behavior of partitions on the out-ofplane SEISMIC DEMANDS of these components simultaneously and the main purpose of this study is to investigate the effect of these cases together. This research involves assessing the SEISMIC performance of partitions made of the hollow brick located in different stories of 3-, 7-and 11-story buildings containing 3D reinforced concrete special moment frames and subjected to a suite of 7 appropriate earthquakes. A finite element program, OpenSees, has been used for nonlinear SEISMIC response history analysis. The average of the peak of responses of partition, under the SEISMIC excitations, was computed for any model and the forces obtained using the analytical method, which some of them verified with existing studies results, were compared with the values from the code. For the majority of the models, the results show that the analytical SEISMIC DEMANDS on partitions, in the lower half, are higher than those calculated using the code provisions because of the effect of higher modes of the structures and the peak values is even up to 1. 54 times the computed value based on the code. The code provisions are conservative for the partitions in the upper half of the buildings.

Nowadays, the uses of SEISMIC isolators as earthquake resistant systems are rapidly increasing. So, in recent years, Iranian researchers have been doing a lot of research on SEISMIC isolators, and results have been published as guidelines for SEISMIC isolated buildings. But, in these regulations, the effects of the near- field earthquake SEISMIC requirements are not mentioned. As earthquake magnitude increases, effects owing to duration, long-period ground motion and near source pulses become more important; in these respects, the current practice may be inadequate. For near-fault locations, the code section on base-isolated buildings requires site-specific analyses, which could produce satisfactory results if the ground-motion consultant makes a realistic recommendation.Near-field earthquakes due to their severe destructive effect are more important, such that extensive research on the different types of records and their impact on structures are investigated. This paper discusses the SEISMIC requirements of buildings with SEISMIC isolators subjected to multicomponent earthquakes. Parameters, such as the inter-story drift, distribution of earthquake force, and displacement of SEISMIC isolators, have been studied, discussed, and compared the values proposed by the guidelines. In order to evaluate the SEISMIC behavior of buildings with SEISMIC isolation subjected to near-field earthquakes, the study included four groups of structures: three-, five-, seven-, and ten-story; each of the four groups of buildings with base isolators was designed for five periods as: 1, 1.5, 2, 2.5, and 3 seconds. For structural analysis of the supposed models, the Open Sees software was used and P-_ effects were considered in the analysis. Each of the structures was analyzed under multi-component non-linear time history of earthquake. According to the result, the results of the method of equivalent static values and those of time history analysis are different; by increasing the period of structures, the non-uniform distribution of story shear in elevation is deformed to uniform distribution.

Effect of soil-structure interaction (SSI) and site condition on elastic and inelastic SEISMIC DEMANDS of structure is investigated in this research. More emphasis is on Effect of soil-structure interaction and site condition is assessed by using earthquakes recorded on different site classes C, D and E (NEHRP [1]) where SSI has a significant effect on the structural DEMANDS because of noticeable difference between the stiffness of soil and the structure. In order to develop a comprehensive statistical parametric study, the structure is modeled as an elastic-plastic single degree of freedom (SDOF) system and the soil beneath the foundation is supposed as a homogeneous half space and is idealized by fundamental lumped mass parameters based on the concepts of the cone model (Wolf, 1994 [17]). To consider the frequency dependency of soil’s dynamic stiffness in this model, the soil is represented with a three-DOF system that introducing an internal DOF in the soil can represent this effect. Then the whole of soil-structure model is analyzed under 45 earthquakes recorded on previously mentioned site classes. A parametric study is done for a wide range of non-dimensional parameters controlling the SSI effects on structural DEMANDS. It is concluded that SSI affects on structural SEISMIC DEMANDS such as elastic and inelastic strength, strength reduction factor, ductility demand, and inelastic displacement ratio especially for structures located on site class E. Results exhibit remarkable differences in comparison to fixed base one. Consequently, in some cases, using parameters derived for fixed base case, lead to non-conservative results in design and assessment parameters of structures located on soft soils.

Always share of damages of non-structural components is a significant share of the total cost of earthquake damages. A simple method for analyzing the response of non-structural members, is use the floor response spectrum. In this method, first behavior of primary structure at the non-structural member nodes regardless of their interaction is determined. Then the response of non-structural members used as input to the analysis result. In this study, six two-dimensional steel moment frame, three, six and twelve-story is modeled. In order to investigate the effect of changing period in the force exerted on non-structural components there are two models, one with more (flexibility) and one with a smaller period (rigid). 7 record ground motion recorded on soil types that respect to the code design of the buildings against earthquakes (Iran standard no. 2800) scale, has been used for time history analysis. The results obtained were compared with suggested values by conventional codes. From this study it was concluded that the focus of energy absorbing of structures is related to the first e and second mode and the height increases, the tendency to absorb energy will be increased. Distribution of amplification factor of SEISMIC response at high (ratio of peak floor acceleration to the peak ground acceleration) to studied frames showed that the amplification factor proposed by Euro code 8 are closer than to be obtained when the period of non-structural component is closer to of the first period of the structure, the phenomenon of resonance occurs and when the structural period increases (tall buildings) effect of higher modes is increased, this means that the resonance mode in the second and third periods will occur.

The effect of the angle of incidence on the structural damage and the SEISMIC demand in far-fault earthquakes has been taken into consideration by many researchers for several decades. However, this issue has recently received more attention from researchers and design codes for near-fault earthquakes. This issue is due to the pulse-type motion caused by forward directivity phenomena in near-fault earthquakes which increases the influence of the angle of incidence on the SEISMIC demand. Due to the importance of the issue, several researches have been conducted in the past years to improve the design criteria for near-fault regions. For example, for Nonlinear Time History Analysis (NTHA), ASCE/SEI 7-16 design code recommended that the selected near-fault ground motions should be first rotated in the fault-normal/fault-parallel directions and then applied to the main axes of the structure. This paper aims to investigate the accuracy and efficiency of the proposed method for design of structures in near-fault regions. For this purpose, using nonlinear macro modeling of an Eccentrically Braced Frame (EBF) and applying near-fault ground motions with different angle of incidence, the SEISMIC DEMANDS of structures were evaluated. The analysis results show that not only the direction of maximum response changes with the change of near-fault ground motions and the types of SEISMIC demand parameters, but also it varies in different stories of a building. Nevertheless, the fault-normal response usually provides an acceptable estimate of the maximum response, which is suitable for design purposes. So that in almost 70% of the cases, the ratio of the fault-normal response to the maximum response is more than 0. 75.