One of the most common irregularities in structures is the irregularity in height and lateral stiffness. Due to the commonness of the use of irregular structures and also the different seismic responses of this type of structures, in comparison with regular structures, investigating the seismic response of irregular structures has always been the subject of several research studies. The structures designed for the reduced base shear, under the design earthquake, have inelastic response. To calculate the real (inelastic) displacements of structures under the design earthquake, the displacements obtained from the reduced base shear, are amplified by the deflection amplification factor (Cd). Seismic codes have dedicated a Cd for each structural system. But different studies have shown that the dedicated Cd by the codes cannot accurately estimate the real displacements. The main purpose of this research is to propose the Cd values for more accurately estimating the maximum inter-STORY DRIFT RATIO (MIDR) and maximum roof DRIFT RATIO (MRDR) in steel special moment resisting frames (SMRFs) with the soft STORY. The number of stories and the location of the soft STORY are the variables considered in this research. The results show that the use of Cd = 5.5, recommended by the 2800 standard and ASCE 7-16 for steel SMRFs, underestimates the real MIDR and also MRDR, under the design earthquake. It is shown that by increasing the number of stories, the mean Cd obtained from the analyses increases. The reason for this issue is the P-Δ effects that increase by increasing the number of stories. In addition, it is shown that a specified trend cannot be found between the location of the soft STORY and the mean Cd values in the stories of the structures. Thus, for more accurately estimating MIDR in the considered structures, under the design earthquake, Cd = 8.5 is proposed. Furthermore, for more accurately estimating MRDR, Cd roof = 8.0 is proposed.

The present study assesses the seismic performance of steel moment resisting frames (SMFs) retrofitted with different bracing systems. Two structural configuRATIOns were utilized: ordinary concentrically braces (OCBFs), buckling-restrained braces (BRBFs). A 7-STORY and 18-STORY steel perimeter SMFs were designed with insufficient lateral stiffness to satisfy code DRIFT limitations in high seismic hazard zone. The frames were then retrofitted with OCBFs with 30, 60, 90, 120 slenderness RATIOs and BRBFs. Inelastic time-hiSTORY analyses have been carried out using OPENSEES software for strain hardening from 1 to 10 percent to assess the structural performance under earthquake ground motions. Inter STORY DRIFTs were employed to compare the inelastic response of the retrofitted frames. It is shown that the distribution of maximum STORY DRIFTs in the height of BRBFs is more uniform than OCBFs with various slenderness RATIOs and with increasing strain hardening, the inter STORY DRIFT and P-D effects is decreased. In addition, normal buckling braces with low slenderness RATIO behave similar to the BRBFs to control inter STORY DRIFT, but the cycling behavior in dissipation the energy can’t be changed, and finally the suitable performance from BRBF can’t be obtained.

In this study, the seismic inter-STORY DRIFT of structures is estimated by a combination of mode-acceleRATIOn equations with the modelling of high-rise buildings with flexural and shear cantilever beams. In the equation presented for calculating the inter-STORY DRIFT, having less knowledge of the building is adequate and this issue is of significance in estimating the nonstructural component forces, especially in high-rise buildings and also in the initial design of structures. Also, a comparison of inter-STORY DRIFT estimated by the approximation method with an exact method indicates that the application of the mode-acceleRATIOn method compared to mode-displacement with a fewer number of modes comes close to the exact calculation, which facilitates and expedites the analysis. In order to carry out an exact evaluation of the presented equation, inter-STORY DRIFT is calculated and compared in 10, 15 and 50 STORY buildings during three seismic records using approximate relations. Exact analysis of those structures is done in finite element Opensees software. The results of comparisons show that the presented equation provides an adequate estimation without the need for modelling and lengthy software analysis.

In seismic resistant design of structures, seismic demands are mainly governed by three factors including the peak value of ground motion, the characteristic of earthquake spectrum and duRATIOn. An earthquake intensity index of ground motions is normally used as a scaling parameter that is critical for seismic analysis and design. A number of researchers have, from their own perspective, proposed various intensity indices. However, due to the complexity and randomness of earthquake motion, it has been a difficult task to accurately evaluate the applicability of various existing intensity indices. In addition, there is a lack of quantitative methods in the evaluation of the applicability of such indices. This has been a challenging issue in seismic engineering research and has become a fundamental problem in performance-based seismic design. Nonlinear structural response is often highly sensitive to the scaling of input ground motions. Thus, many different ground motion scaling methods have been proposed. The “ severity” of an earthquake ground motion is often quantified by an intensity measure, IM, such as peak ground acceleRATIOn, PGA, or spectral acceleRATIOn at a given period. The PGA of a record was a commonly used IM in the past. More recently, spectral response values such as spectral acceleRATIOn at the fundamental period of vibRATIOn have been used as IM. Scaling of ground motions to a given spectral level at the fundamental period of vibRATIOn significantly decreases the variability in the maximum demand observed in the structural system. However, it is widely known that for records with the same spectral acceleRATIOn at the fundamental period of vibRATIOn value, spectral shape will affect the response of multi-degree-of-freedom (MDOF) and nonlinear structures, because spectral values at other periods affect the response of higher modes of the structure as well as nonlinear response when the structure’ s effective period has lengthened. Previous studies have focused on evaluation of different ground motion scaling methods in SDOF and buildings with shear-type behavior or common steel-moment frame structures. However, over the last decade, the performance-based seismic design (PBSD) philosophy has emerged as a promising and efficient seismic design approach. The novel Performance-based plastic design (PBPD) approach explicitly accounts for the inelastic behavior of a structural system in the design process itself. PBSD approaches based on plastic analysis and design concepts were recently developed for different lateral load resisting systems such as steel moment resisting frames, steel braced frames, etc. The analytical validation of these methods showed that structures designed using these methods were very effective in achieving the pre-selected performance objectives. Considering a gradual shift towards PBSD, this study is aimed at examining the effects of six different IMs on the estimation and distribution of the maximum inter-STORY DRIFT for three short, moderate, and long-period steel-moment resisting frames designed with PBPD method. An ensemble of 42 far-filed earthquake ground motions without pulse characteristics were used and scaled based on two target spectrum MCE and Design Response Spectrum to conduct nonlinear dynamics analyses by using OPENSEES. Results indicate that, the cod-compliant scaling method was not reliable for nonlinear dynamic analyses of structures designed by PBPD method, and cloud be very sensitive to the ground motion characteristics. Among them, depending on the number of stories, the three scaling methods including scaling ground motions to a given PGA and those that take into account for periods of higher modes generally decrease the variability in the maximum demand observed in the structural systems.

The incident angle of ground motion is one of the sources of uncertainty in the seismic response of buildings. Moreover, understanding the structural response to the impose ground motion may cause significant changes in the maximum response of buildings. In order to investigate the influence of the spatial distribution of orthogonal components of earthquake strong motion on the structural responses, three 15-STORY buildings were analyzed in this study using the time-hiSTORY method. A significant live load (750 kg/m2) is imposed at different vertical levels of the structures. The imposed load was combined with ground motion excitations in the range of 0 to 90 degrees. The response of structure was investigated using roof DRIFT index and inter-STORY DRIFT RATIO. Results demonstrate the orientation of seismic excitation and considering the maximum values of roof DRIFT index, which correspond to the critical direction increase roof DRIFT index between 8 to 12 percent. Furthermore, the inter-STORY DRIFT RATIO increased between 30 to 33 percent due to the orientation of excitation and considering the maximum values of the inter-STORY DRIFT RATIO, which correspond to the critical direction.

Fling-step and forward directivity are two important characteristics of near-field earthquakes. Forward directivity occurs when the rupture propagates toward the site and arises in fault‐ normal direction for strike‐ slip faults. Fling-step is the consequence of permanent ground displacement imposed by near-field earthquakes and arises in strikeslip faults in the strike parallel direction. Fling-step effect produces permanent displacement at the end the culmination of displacement time hiSTORY. This effect is usually omitted from the main record using the standard processing methods and therefore, cannot be determined for different structures. Many studies were performed to obtain seismic response of different structures subjected to near-field earthquake having forward directivity. On the other hand, there are few references to investigate the effect of flingstep on seismic behavior of structures. For this purpose, 14 earthquake records with flingstep are selected in a way that important factors including fling-step, PGV, PGA and the energy application type are different. The selected records are applied to eccentrically braced frame structures with 3, 6, 9 and 12 stories. A nonlinear time hiSTORY analysis is used to capture displacement and STORY-DRIFT RATIO responses. The results show that the fling-step effect has no significant impact on any of the considered structures and its effect can be neglected in the case of eccentrically braced frame structures.

In statistics it is often assumed that sample observations are independent. But sometimes in practice, observations are somehow dependent on each other. Spatiotemporal data are dependent data which their correlation is due to their spatiotemporal locations. Spatiotemporal models arise whenever data are collected across both time and space. Therefore such models have to be analyzed in terms of their spatial and temporal structure. Usually a spatiotemporal random field {Z(s, t) : (s, t) Î D x T} is used for modeling the spatiotemporal data, where D Ì Rd, d ³ 1 is a space region and T Í R is a time region. One of the fundamental subjects in analyzing such data is prediction. In spatial statistics, assuming that the spatiotemporal random field Z(s,.t) is stationary with finite variance at all coordinates (s, t) Î D x T, and spatiotemporal covariance function C(h, u) = cov (Z(s, t)j Z(s + h, t + u)) exists, the unknown value of the random field at a given location (s0, t0) is usually predicted with kriging as the best linear unbiased predictor. In practice, the spatiotemporal covariance function is unknown and a positive definite function should be fitted to the estimates of the covariance function. To ensure that a valid spatiotemporal covariance model is fitted to the data, one usually considers a parametric family whose members are known to be separable positive definite functions. A separable spatiotemporal covariance function might decompose into sum or product of a purely spatial and a purely temporal covariance function. In this paper the product-sum model introduced by De Iaco et al. (2001) is used to determine the spatiotemporal correlation of the data.In some applied problems, in addition to the values of an attribute of interest Z(0, 0), some additional information is available in each sample location, so the precision of prediction would be improved by their implementation. In this paper, to exploit this additional information in kriging, two techniques for spatiotemporal kriging of temperature are compared. The first technique, spatiotemporal ordinary kriging, is the simplest of the two, and uses only information about temperature. The second technique, spatiotemporal kriging with external DRIFT, uses also the relationship between temperature and height to aid the interpolation. It is shown that the behavior of the temperature predictions is physically more realistic when using spatiotemporal kriging with external DRIFT. The implementation of spatiotemporal kriging with external DRIFT, then, is illustrated in a real problem, consisting of maximum and minimum temperature of 6 provinces in Iran.

Coupled steel plate shear wall consist of two shear wall with flat web plate with rigid beam-column connection, that connected with coupling beam at STORY level. Coupled steel plate shear wall consist of two panels with rigid beam-column connection, that connected with coupling beam at STORY level so its possible to use opening in wall. In this study, two types of six STORY steel plate shear wall with coupling beam with trapezoidally corrugated infill plate designed with performance plastic design method and two other types designed with force base design. All models have been designed in ABAQUS software and the software outputs were compared and verified by the behavioral mechanism of uncoupling shear wall of the trapezoidal corrugated sheet and the shear wall of the flat web sheet. Subsequently, these four samples were analuzed with time hiSTORY analysis with the three Northridge, Kobe and Tabas earthquake records. Investigated output of this study consist of relative DRIFT at the peak of maximum displacement of each records and residual DRIFT. With the result of these four models figure out that relative DRIFT are in allowable DRIFT RATIO (2%). But each design procedure has advantages than the other one. Advantages of performance plastic design in comparison with force base design are consume less steel material and distribute uniform relative DRIFT RATIO. While the advantages of force base design has less relative DRIFT RATIO. Hence, in frames which designed by force-based design in comparison with performance based plastic design has less residual DRIFT.