Given the inherently time-consuming nature of incremental dynamic Analysis (IDA), which requires extensive computational resources to simulate multiple ground motions and assess various structural responses, it is essential to explore more efficient methodologies that maintain accuracy while reducing analysis time. The MPA-based IDA algorithm (MIDA) is being developed for various structures to address the limitations of IDA. In this study, six individual masonry structures were examined, including three walls with varying perforation dimensions and three three-dimensional buildings subjected to two retrofitting conditions. These structures were analyzed using 30 ground motion accelerations. The masonry structures, reinforced with either a shotcrete layer or a coating application, were evaluated as homogeneous and anisotropic materials using a finite element-based macro-modeling approach. Additionally, IDA was performed, and the maximum displacement of the masonry structures was compared to that of the MIDA. The results indicate that, except under high surcharge conditions, the MIDA procedure not only significantly reduces computational time but also provides reasonable accuracy compared to the IDA precision algorithm. Therefore, it can be concluded that the difference between the IDA and MIDA methods is influenced by the lateral stiffness of the masonry structures being analyzed

incremental dynamic Analysis (IDA) procedure is now considered as a robust tool for estimating the seismic sidesway collapse capacity of structures. However, the procedure is time-consuming and requires numerous nonlinear response-history analyses. This paper proposes a simplified Modal Pushover Analysis (MPA) procedure for IDA of RC moment-resisting frames. The proposed method uses the dynamic response of an equivalent single-degree-of-freedom system, characterized by a bilinear relationship between the lateral force and roof-displacement. This relationship is determined by the ‘ first-mode’ pushover analysis of the structure. Four regular RC moment-resisting frames designed based on the current US building codes are selected and subjected to the proposed method. The analysis results obtained from the original MPA-based IDA method, Static Push-Over to incremental dynamic Analysis (SPO2IDA) and the method proposed by Shafei et al are also presented for comparison. The performance of the proposed method is then evaluated through comparisons with the results obtained from IDAs. The results show that the proposed method can efficiently estimate the dynamic capacity of the example buildings for different seismic intensities. Nonetheless like to MPAbased IDA and SPO2IDA methods less accurate results are obtained by the proposed procedure for 16% and 84% IDA fractiles in most case studies.

Determination of nonlinear dynamic behavior of structures has always been one of the main goals of both structural and earthquake engineers. One of the newest methods for analyzing seismic behavior of structures is Modal incremental dynamic Analysis (MIDA). In fact, this method is an alternative to the incremental dynamic Analysis (IDA), which is a dificult and time-consuming method. Despite the MIDA's approximate results, advantages such as adequate accuracy, high speed, and low cost make this method an efficient and appropriate approach. In all the previous studies, the proposed models have had a regularized plan; hence, all the analyses have been carried out on a frame. In this study, the MIDA analysis was developed in an asymmetric-plan-type building by considering three structures with 4, 7, and 10 stories having irregularity in plan. Accuracy of the work was examined. Also, through a simplification, instead of considering an unconventional plan, we used a rectangular plan with an eccentricity of 15% between the center of mass and the center of rigidity. Comparing the results of this study and the IDA method proved the high level of accuracy of this method in assessing seismic demands.

Modal analysis is a process of describing a structure in terms of its natural characteristics which are the frequency, damping and mode shapes-its dynamic properties [1]. The change of Modal characteristics directly provides an indication of structural condition based on changes in frequencies and mode shapes of vibration. This paper presents results of an experimental Modal analysis of beams made with different materials such as Steel, Brass, Copper and Aluminum. The beams were excited using an impact hammer excitation technique over the frequency range of interest, 0–2000 Hz. Frequency response functions (FRFs) were obtained using OROS vibration analyzer. The FRFs were processed using NV Solutions Modal analysis package to identify natural frequencies, Damping and the corresponding mode shapes of the beams.

It is generally accepted that performance-based design has to be reliability-based. Seismic performance evaluation is based on nonlinear dynamics and reliability theory taking into account uncertainties during analysis. Considering the economic importance of jacket type offshore platforms, the present research aims to assess the seismic performance of offshore steel platforms. In this study, three platforms located in the Persian Gulf were modeled using three dimensional structural modeling tools. Each platform was modeled and analyzed using both rigid and pinned connections. Reliability analysis was performed in accordance with Federal Emergency Management Agency (FEMA) guidelines using the results of incremental dynamic analysis for the three platforms. The results showed that platforms possessing rigid connections provide the desired confidence level of FEMA for the performance level of collapse prevention while only one platform with pinned connections was able to provide the desired confidence level.