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.

Seismic Fragility Curves for Performance of Semi-rigid Connections of Steel Frames

A steel frame with a semi-rigid connection is one of the most widely used structural systems in modern construction. These systems are cheap to make, require less time to construct and offer the highest quality and reliable construction quality without the need for highly skilled workers. However, these systems show greater natural periods compared to their perfectly rigid frame counterparts. This causes the building to attract low loads during earthquakes. In this research study, the seismic performance of steel frames with semi-rigid joints is evaluated. Three connections with capacities of 50, 70 and 100% of the beam’s plastic moment are studied and examined. The seismic performance of these frames is determined by a non-linear static pushover analysis and an incremental dynamic analysis leading finally to the fragility curves which are developed. The results show that a decrease in the connection capacity increases the probability of reaching or exceeding a particular damage limit state in the frames is found. Doi: 10.28991/cej-2021-03091714 Full Text: PDF

SEISMIC EVALUATION OF HIGH RISE BUILDING WITH VERTICAL IRREGULARITIES BY PUSHOVER ANALYSIS

During earthquake motion. The seismic behavior depends upon the strength, mass, and stiffness are distributed in both horizontal and vertical planes. the buildings structural damage was severe the frame is caused due to the discontinuity in the stiffness mass and strength between the alongside stories. The same type of discontinuity is vertical geometric irregularity which is due to the irregular building configuration in vertical plane so there is to know the seismic response of building modals in different structural irregularities. Non-linear static (pushover analysis) which is used for Investigation. The purpose of study doing nonlinear static (pushover analysis) by conventional design methodology G+12 High rise buildings this work shows seismic performance and behavior of building frame with and without vertical irregularity in terms of base shear, story shear, story displacement the performance point of all models are considered also found that irregularity in assessment of the structure decreases the performance level of building there is also reduces in deformation or displacement of the structure. all the models analyzed by using ETABS and design as per IS 456:200 and 1893:2016

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.

Non-Linear Static Analysis of RCC Framed Structures with and Without Infill Walls

The concept of an earthquake is becoming an exceptional study in our use because no longer a particular area can be targeted as an earthquake-resistant area. So, the main motif of any structural engineer during the design is to design a structure that could cope with seismic pressure successfully. On this note, non-linear static pushover analysis has become a prominent tool for the structural design and evaluation of RC elements. In this project G + 5, G + 9, G + 5 with infill walls and G + 9 with infill walls RCC framed structures have been analyzed by the use of SAP 2000 v19. The structures are designed as in keeping with IS 1893(Part 1): 2002 for earthquake forces in seismic zone IV. The use of the equivalent strut approach for modeling the infill walls is adopted and strut is designed in accordance with FEMA-356. Non-linear Static pushover analysis is performed on the designed RCC framed structures with and without infill walls. And pushover results are used to evaluate structural performance under design earthquake load, and code requirements are discussed.