Seismic fragility assessment of bridge piers incorporating high-strength steel reinforcement and concrete under near-fault ground motions

2020 ◽  
Author(s):  
Saif Aldabagh ◽  
Saqib Khan ◽  
M. Shahria Alam
Keyword(s):  
High Strength Steel ◽  
Load Capacity ◽  
Fragility Curves ◽  
Time History ◽  
Inelastic Strain ◽  
High Strength ◽  
The United States ◽  
Bridge Piers ◽  
Seismic Fragility ◽  
Damage States

Design codes in the United States and Canada limit the use of high-strength steel (HSS) and high-strength concrete (HSC) to bridge components that are expected to remain elastic during a seismic event. Although HSS and HSC have higher tensile and compressive strengths, respectively, their lower inelastic strain capacities impose for such restrictions. To assess the seismic performance of HSS and HSC, the pier of an existing bridge is redesigned using concrete compressive strength of 50 and 80 MPa, and reinforcement yield strength of 420, 690, and 830 MPa. Static pushover and nonlinear dynamic time-history analyses were performed to generate force-deformation and seismic fragility curves. Bridge piers incorporating HSS and HSC attained the maximum load capacity yet were the least ductile. They were less seismically vulnerable than those incorporating conventional materials at minimal and repairable damage states, but not at extensive and probable replacement damage states.

scholarly journals Seismic Fragility Assessment of Base-Isolated Steel Water Storage Tank

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zhuo Zhao ◽  
Xiaowei Lu ◽  
Yu Guo ◽  
Xiaofeng Zhao
Keyword(s):  
Storage Tank ◽  
Shear Force ◽  
Fragility Curves ◽  
Water Storage ◽  
Time History ◽  
Seismic Fragility ◽  
Coefficient Of Determination ◽  
Base Shear ◽  
Water Storage Tank ◽  
Demand Models

Steel water storage tanks (WSTs) are among the important components of water treatment industry facilities that are expected to remain functional and applicable after strong earthquakes. In this study, the seismic vulnerability of base-isolated steel WST is investigated. A three-dimensional finite element stick model of the targeted tank is created using OpenSees. This model is capable of reproducing convective, impulsive, and rigid responses of fluid-tank systems. Time-history responses of convective displacement, bearing displacement, and base shear force for base-isolated tank subjected to a typical ground motion are compared. Furthermore, time-history analysis based on a suite of 80 ground motions is conducted. The seismic demand models for various responses are established and the most efficient intensity measure (IM) is determined based on the dispersion and coefficient of determination. Seismic fragility curves for different responses are derived for all three damage states using cloud analysis. The results from this study reveal that (i) the convective displacement is significantly greater than bearing displacement; (ii) peak ground displacement (PGD) is the most efficient and sufficient IM for the targeted tank; and (iii) the characteristic of isolation bearing significantly influences the seismic fragilities of convective displacement and bearing displacement and has a little impact on base shear force, which makes the selection of the proper characteristic parameters for isolation bearing very essential. The analysis technique and procedure mentioned above as well as derived insights are of significance to general liquid storage tank system configuration.

Seismic Fragility Analysis of Mid-Story Isolation and Reduction Structures Based Two Directions

2013 ◽  
Vol 739 ◽  
pp. 309-313 ◽  
Author(s):  
Pei Ju Chang
Keyword(s):  
Fragility Curves ◽  
Response Spectrum ◽  
Time History ◽  
Longitudinal Axis ◽  
Seismic Intensity ◽  
Seismic Fragility ◽  
Infill Wall ◽  
Intensity Index ◽  
History Analysis ◽  
Masonry Infill Wall

This study focus on derivation of such fragility curves using classic mid-story isolation and reduction structures (MIRS) in China metropolis. This study focus on derivation of such fragility curves using conventional industrial frames with masonry infill wall. A set of stochastic earthquake waves compatible with the response spectrum of China seismic code selected to represent the variability in ground motion. Dynamic inelastic time history analysis was used to analyze the random sample of structures. MIRS seismic capability of longitudinal and transversal orientation is different. Stochastic damage scatter diagrams based different seismic intensity index are obtained. Seismic fragility of longitudinal axis (Y axis) is larger than transversal axis (X axis) of frames under major earthquake obviously.

UAV Based Multi-Hazard Vulnerability Assessment System for Bridges Exposed to Scour

2020 ◽  
Author(s):  
Okan Özcan ◽  
Orkan Özcan
Keyword(s):  
Load Capacity ◽  
Time History ◽  
Element Model ◽  
Lateral Load ◽  
Assessment System ◽  
Bridge Piers ◽  
Scour Depth ◽  
River Bed ◽  
Principal Axes

<p>Evaluating the multi-hazard performance of river crossing bridges under probable earthquake, flood, and scouring scenarios is a cumbersome task in performance-based engineering. The loss of lateral load capacity at bridge foundations may induce bridges to become highly vulnerable to failure when the effects of scour and floods are combined. Besides, the assessment of local scouring mechanism around bridge piers provides information for decision‐making regarding the pile footing design and for predicting the safety of bridges under critical scoured conditions. Thereby, accurate high-resolution Digital Elevation Models (DEMs) are critical for many hydraulic applications such as erosion, hydraulic modelling, sediment transport, and morphodynamics. In the present study, an automated unmanned aerial vehicle (UAV) based multi-hazard performance assessment system was developed to respond to rapid performance evaluation and performance prediction needs for river crossing reinforced concrete (RC) bridges. The Bogacay Bridge constructed over Bogacay in Antalya, Turkey was selected as the case study. In the developed system, firstly the seasonally acquired UAV measurements were used to obtain the DEMs of the river bed from 2016 to 2019. The transverse cross sections of the river bed that were taken close to the inspected bridge were used to measure the depth of the scoured regions along the bridge piles under the present conditions. Separately, in conjunction with the flood simulation and validation with 2003 flood event (corresponds to Q<sub>50</sub>=1940 m<sup>3</sup>/s), the scour depth after maximum probable flood load according to the return period of 500 years (Q<sub>500</sub>=2560 m<sup>3</sup>/s) were predicted by HEC-RAS software. Afterwards, the 3D finite element model (FEM) of the bridge was constituted automatically with the developed code considering the scoured piles. The flood loads were exerted on the modeled bridge with regard to the HEC-RAS flood inundation map and relevant water depth estimations around the bridge piers. For the seismic evaluation, nonlinear time history analyses (THA) were conducted by using scaled eleven scaled earthquake acceleration records that were acting in both principal axes of the bridge simultaneously by considering maximum direction spectra (SaRotD100) as compatible with the region seismicity. In the analyses; as the scour depth increased, the fundamental periods, shear forces and the bending moments were observed to increase while the pile lateral load capacities diminished. Therefore, the applicability of the proposed system was verified using the case study bridge.</p>

scholarly journals Seismic Fragility And Post-Earthquake Reparability of Concrete Frame With Low-Bond High-Strength Rebar Reinforced Concrete Column

2021 ◽  
Author(s):  
Junhua Wang ◽  
Y.P. Sun
Keyword(s):  
Fragility Curves ◽  
Residual Deformation ◽  
High Strength ◽  
Seismic Fragility ◽  
Present Calculation ◽  
Reinforced Concrete Column ◽  
Seismic Behaviour ◽  
Earthquake Intensity ◽  
Lateral Drift ◽  
Seismic Collapse

Abstract To further study the global seismic behaviour and post-earthquake reparability of RC building frames with the proposed self-centring columns with low-bond high-strength reinforcements (LBHSRs), incremental dynamic analysis (IDA) of five-floor and ten-floor frame archetypes under excitation by twenty ground motions (GMs) was performed. First, the pushover results indicated that the use of LBHSR could substantially improve the yield and ultimate lateral drift of both the archetypes, although the archetype had a smaller longitudinal reinforcement ratio (LR) of the LBHSR and similar seismic resistance. The dynamic response results indicated that the archetype with LBHSRs exhibited a smaller residual story lateral drift although the effectiveness of the use of LBHSR to reduce seismic response was not apparent for the archetype subjected to a low-intensity earthquake. The seismic fragility results showed that LBHSR was more effective for preventing seismic collapse than for attaining the immediate occupancy (IO), life safety (LS), and collapse prevention (CP) limit states. Furthermore, the higher the LR, the lower was the likelihood of seismic collapse. The fragility curves of the residual story lateral drifts indicate that the use of LBHSR can significantly mitigate the residual deformation in the DS1, DS2, and DS3 damage states. Moreover, the effectiveness increases with the increase in the LR and earthquake intensity. Comparisons of residual story lateral drifts between the predicted results and IDA results indicated that the present calculation models are not suitable for predicting residual deformation. The model needs to be studied further.

Seismic Fragility of Suspended Ceiling Systems

2007 ◽  
Vol 23 (1) ◽  
pp. 21-40 ◽  
Author(s):  
Hiram Badillo-Almaraz ◽  
Andrew S. Whittaker ◽  
Andrei M. Reinhorn
Keyword(s):  
Seismic Performance ◽  
Dynamic Testing ◽  
Fragility Curves ◽  
Full Scale ◽  
Seismic Fragility ◽  
Limit States ◽  
Performance Based Assessment ◽  
Damage States

Full-scale dynamic testing of suspended ceiling systems was performed to obtain fragility data suitable for performance-based assessment and design. On the basis of the fragility data derived from testing, (1) the use of retainer clips improves the performance of ceiling systems in terms of loss of tiles, (2) including recycled cross tees in the suspension grid increases the vulnerability of the ceiling systems, (3) undersized (poorly fitting) tiles are substantially more vulnerable than properly fitted tiles, and (4) the use of compression posts improves the seismic performance of ceiling systems for the limit states of minor and moderate damage. Fragility curves are provided for four damage states.

scholarly journals Seismic Fragility Assessment of Steel Liquid Storage Tanks

2015 ◽  
Author(s):  
Konstantinos Bakalis ◽  
Dimitrios Vamvatsikos ◽  
Michalis Fragiadakis
Keyword(s):  
Failure Modes ◽  
Fragility Curves ◽  
Seismic Fragility ◽  
Assessment Procedure ◽  
Storage Tanks ◽  
Component Level ◽  
Damage State ◽  
Liquid Storage ◽  
Damage States ◽  
Buckling Failure

A seismic fragility assessment procedure is developed for atmospheric steel liquid storage tanks. Appropriate system and component-level damage states are defined by identifying the failure modes that may occur during a strong ground motion. Special attention is paid to the elephant’s foot buckling failure mode, where the estimation of the associated capacity and demand requires thorough consideration within a probabilistic framework. A novel damage state is introduced to existing procedures with respect to the uncontrollable loss of containment scenario. Fragility curves are estimated by introducing both aleatory and epistemic sources of uncertainty, thus providing a comprehensive methodology for the seismic risk assessment of liquid storage tanks. The importance of dynamic buckling is acknowledged and the issue of non-sequential damage states is finally revealed.

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