Comparison of steel frames with RWS and WFP beam-to-column connections through seismic fragility analysis

2020 ◽  
pp. 136943322097728
Author(s):  
Haoran Yu ◽  
Weibin Li
Keyword(s):  
Limit State ◽  
Pushover Analysis ◽  
Steel Frames ◽  
Fragility Analysis ◽  
Structural Safety ◽  
Seismic Fragility ◽  
Fe Modelling ◽  
Collapse Resistance ◽  
Seismic Collapse ◽  
Probabilistic Seismic Demand

Reduced web section (RWS) connections and welded flange plate (WFP) connections can both effectively improve the seismic performance of a structure by moving plastic hinges to a predetermined location away from the column face. In this paper, two kinds of steel frames—with RWS connections and WFP connections—as well as different frames with welded unreinforced flange connections were studied through seismic fragility analysis. The numerical simulation was conducted by using multiscale FE modelling. Based on the incremental dynamic analysis and pushover analysis methods, probabilistic seismic demand analysis and seismic capability analysis were carried out, respectively. Finally, combined with the above analysis results, probabilistic seismic fragility analysis was conducted on the frame models. The results showed that the RWS connection and WFP connection (without double plates) have little influence on reducing the maximum inter-storey drift ratio under earthquake action. RWS connections slightly reduce the seismic capability in non-collapse stages and improve the seismic collapse resistance of a structure, which exhibits good structural ductility. WFP connections can comprehensively improve the seismic capability of a structure, but the seismic collapse resistance is worse than that of RWS connections when the structure has a large number of storeys. The frame with WFP connections has a lower failure probability at every seismic limit state, while the frame with RWS connections sacrifices some of its structural safety in non-collapse stages to reduce the collapse probability.

scholarly journals Dynamic Damage Mechanism and Seismic Fragility Analysis of an Aqueduct Structure

2021 ◽  
Vol 11 (24) ◽  
pp. 11709
Author(s):  
Xinyong Xu ◽  
Xuhui Liu ◽  
Li Jiang ◽  
Mohd Yawar Ali Khan
Keyword(s):  
Ground Motion ◽  
Structural Damage ◽  
Large Scale ◽  
Seismic Analysis ◽  
Fragility Curves ◽  
Limit State ◽  
Fragility Analysis ◽  
Seismic Fragility ◽  
Exceedance Probability ◽  
Computation Efficiency

The Concrete Damaged Plasticity (CDP) constitutive is introduced to study the dynamic failure mechanism and the law of damage development to the aqueduct structure during the seismic duration using a large-scale aqueduct structure from the South-to-North Water Division Project (SNWDP) as a research object. Incremental dynamic analysis (IDA) and multiple stripe analysis (MSA) seismic fragility methods are introduced. The spectral acceleration is used as the scale of ground motion record intensity measure (IM), and the aqueduct pier top offset ratio quantifies the limit of structural damage measure (DM). The aqueduct structure’s seismic fragility evaluation curves are constructed with indicators of different seismic intensity measures to depict the damage characteristics of aqueduct structures under different seismic intensities through probability. The results show that penetrating damage is most likely to occur on both sides of the pier cap and around the pier shaft in the event of a rare earthquake, followed by the top of the aqueduct body, which requires the greatest care during an earthquake. The results of two fragility analysis methodologies reveal that the fragility curves are very similar. The aqueduct structure’s first limit state level (LS1) is quite steep and near the vertical line, indicating that maintaining the excellent condition without damage in the seismic analysis will be challenging. Except for individual results, the overall fragility results are in good agreement, and the curve change rule is the same. The exceedance probability in the case of any ground motion record IM may be estimated using only two factors when using the MSA approach, and the computation efficiency is higher. The study of seismic fragility analysis methods in this paper can provide a reference for the seismic safety evaluation of aqueducts and similar structures.

Enhanced Seismic Fragility Analysis of Unanchored Steel Storage Tanks Accounting for Uncertain Modeling Parameters

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Hoang Nam Phan ◽  
Fabrizio Paolacci ◽  
Silvia Alessandri
Keyword(s):  
Seismic Vulnerability ◽  
Failure Modes ◽  
Fragility Curves ◽  
Pushover Analysis ◽  
Sampling Procedure ◽  
Fractional Factorial ◽  
Fragility Analysis ◽  
Seismic Fragility ◽  
Bottom Plate ◽  
Storage Tanks

Catastrophic failure of the above ground steel storage tanks was observed during past earthquakes, which caused serious economic and environmental consequences. Many of the existing tanks were designed in the past with outdated analysis methods and with underestimated seismic loads. Therefore, the evaluation of the seismic vulnerability of these tanks, especially ones located in seismic prone areas, is extremely important. Seismic fragility functions are useful tools to quantify the seismic vulnerability of structures in the framework of probabilistic seismic risk assessment. These functions give the probability that a seismic demand on a given structural component meets or exceeds its capacity. The objective of this study is to examine the seismic vulnerability of an unanchored steel storage tank, considering the uncertainty of modeling parameters that are related to material and geometric properties of the tank. The significance of uncertain modeling parameters is first investigated with a screening study, which is based on nonlinear static pushover analyses of the tank using the abaqus software. In this respect, a fractional factorial design and an analysis of variance (ANOVA) have been adopted. The results indicate that the considered modeling parameters have significant effects on the uplift behavior of the tank. The fragility curves of two critical failure modes, i.e., the buckling of the shell plate and the plastic rotation of the shell-to-bottom plate joint, are then developed based on a simplified model of the tank, where the uplift behavior is correctly modeled from the static pushover analysis. The uncertainty associated with the significant parameters previously identified are considered in the fragility analysis using a sampling procedure to generate statistically significant samples of the model. The relative importance of different treatment levels of the uncertainty on the fragility curves of the tank is assessed and discussed in detail.

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

2021 ◽  
Vol 7 (7) ◽  
pp. 1112-1124
Author(s):  
Mohamed Saadi ◽  
Djarir Yahiaoui ◽  
Noureddine Lahbari ◽  
Bouzid Tayeb
Keyword(s):  
Seismic Performance ◽  
Fragility Curves ◽  
Limit State ◽  
Pushover Analysis ◽  
Steel Frames ◽  
Skilled Workers ◽  
Rigid Frame ◽  
Rigid Connection ◽  
Rigid Joints ◽  
Static Pushover Analysis

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

SVM Based Seismic Fragility Analysis for RC Isolated Continuous Girder Bridge

2013 ◽  
Vol 800 ◽  
pp. 229-235 ◽  
Author(s):  
Xiao Hong Long ◽  
Bei Lei Chen ◽  
Jian Jun Li
Keyword(s):  
Fragility Curves ◽  
Longitudinal Direction ◽  
Fragility Analysis ◽  
Seismic Fragility ◽  
Research Report ◽  
Lateral Direction ◽  
Probabilistic Seismic Demand Analysis ◽  
Continuous Girder Bridge ◽  
Probabilistic Seismic Demand ◽  
Girder Bridge

Because the fragility analysis methods used in recent years have some disadvantages to some extent, and there is no relative research report on the seismic fragility of structures based on SVM algorithm, nonparametric analytical method is used in the probabilistic seismic demand analysis, and fragility curves of RC isolated continuous bridge are obtained based on SVM Method. It turns out that the analytical results of SVM Method and Cloud Method are different in the longitudinal direction, matched in the lateral direction, and the results of the former method are greater than the latter one. It is a new and meaningful research that is more efficient than IDA method and also reliable.

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