Study on the Development of Seismic Fragility of Steel SMRF

Vulnerability assessment of the structure is the most important and wide area of research which requires more input from the engineers and seismologist. The seismic vulnerability assessment of the structure can be evaluated by developing Fragility curves. Fragility curves shows the conditional probability of the structure exceeding the particular performance limit of the given damage state during strong ground motions. Fragility curves can be developed for different parameters like spectral displacement (Sd), spectral acceleration (Sa) Peak ground acceleration (PGA) , Inter storey drift ratio (IDR) etc. This paper describes about the different methods used in deriving the Fragility curves like conventional methods, Nonlinear Dynamic analysis methods and Nonlinear Static analysis methods. Also the fragility analysis of 5 Storied Steel Moment Resisting Frame (SMRF) has been carried out based on the parameters suggested by HAZUS M.H 2.1. Nonlinear static pushover analysis of the frame has been carried out in ETABS2016. Fragility curves are developed based on the pushover analysis results. The damage states defined as per HAZUS are Slight damage (SD), Moderate damage (MD) Extensive damage (ED) and Complete damage (CD). After carrying out the fragility analysis for the steel SMRF, it has been found out that, as the spectral displacement increases probability of failure for the slight damage of the structure is very high and the probability of failure for the complete damage is very low. Hence the probability of failure of the structure reduces from slight damage to complete damage. Keywords: Fragility curves, vulnerability assessment, Nonlinear static pushover analysis, HAZUS M.H 2.1.

Analytical Investigation of Response Reduction Factor (R) for R.C. Elevated Water Tank with Non-linear Static (Pushover) Analysis

In the present work, an attempt is made to investigate response reduction factor (R) values of different soil types by using nonlinear static (Pushover) analysis for R.C. elevated rectangular water tank structure. All the parameters were investigated by varying properties of soft, medium and hard soils to cover a method of nonlinear static (Pushover) analysis. The zone factor (Z) kept constant Z – III for pandharpur site location and capacity of 150 m3 tank full in condition. This has resulted into SAP 2000 finite element software. The analysis of response reduction factor (R) value was done under three different soil conditions i.e. soft soil properties, medium soil properties, and hard soil properties. Response reduction factor (R) values indicate that R.C. elevated rectangular water tank structure without soil properties behaves quite the one value as per codal provisions.

Response Reduction Factor for Mansory Buildings

Most of the seismic codes used today incorporate the nonlinear response of a structure by providing an appropriate response reduction factor so that a linear elastic force-based approach can be used in designs. This study focuses on evaluating the response reduction factor for masonry buildings with different mechanical properties, which are used in modern codes to scale down the elastic response of the structure. Using a similar frame-approach, a nonlinear static pushover analysis is carried out on the analytical models of masonry building in finite element analysis software SAP2000v20.0.0. The response reduction factor components, flexibility, and over strength were computed from the results obtained from the nonlinear static pushover analysis. Finally, the response reduction factor is evaluated for different masonry buildings. It is concluded that the R-value given in IS: 1893-2016 for unreinforced masonry is not recommended for random rubble stonemasonry buildings in mud mortar.

Nonlinear Static Pushover Analysis of Medium Rise and High-Rise Building

Pushover analysis is an elegant tool to visualise the performance level of a building under a given earthquake. The purpose of the paper is to summarize the Non Linear static Pushover analysis of medium rise RC bare frame and high rise RC infilled structure with soft stories at different levels using ETABS software. Results concluded that due to the introduction of soft stories in the higher level the intensity of hinge formation becomes lower and lower and at the same time displacement and base shear increases

Seismic Performance Evaluation of a Fully Integral Concrete Bridge with End-Restraining Abutments

A fully integral bridge that is restrained at both ends by the abutments has been proposed to form a monolithic rigid frame structure. Thus, the feasible horizontal force effect due to an earthquake or vehicle braking is mainly prevented by the end-restraining abutments. In a recent study, a fully integral bridge with appropriate end-restraining abutment stiffness was derived for a multispan continuous railroad bridge based on linear elastic behavior. Therefore, this study aims to investigate the nonlinear behavior and seismic capacity of the fully integral bridge and then to assess the appropriate stiffness of the end-restraining abutment to sufficiently resist design earthquake loadings through a rigorous parametric study. The finite element modeling and analyses are performed using OpenSees. In order to obtain the force-deflection curves of the models, nonlinear static pushover analysis is performed. It is confirmed that the fully integral bridge prototype in the study meets the seismic performance criteria specified by Caltrans. The nonlinear static pushover analysis results reveal that, due to the end-restraining effect of the abutment, the lateral displacement of the fully integral bridge is reduced, and the intermediate piers sustain less lateral force and displacement. Then, the sectional member forces are well controlled in the intermediate piers by a proper application of the end-restraining abutments.