Reliability based performance assessment of a roadway bridge under seismic actions

2021 ◽  
Author(s):  
Carlos Mendoza ◽  
José Matos ◽  
Neryvaldo Galvão ◽  
Álvaro Viviescas
Keyword(s):  
Pushover Analysis ◽  
Ground Acceleration ◽  
Surface Method ◽  
Reliability Method ◽  
Common Causes ◽  
Bridge Reliability ◽  
Collapse Failure ◽  
Bridge Failure ◽  
Inspection Techniques

<p>External events represent the most common causes of bridge failure which could indicate distress, partial or total collapse (failure of all substantial parts of a bridge). One of the main environmental factors are earthquakes, which have a high impact on bridges due to irregularities presented in both substructure and superstructure and vulnerabilities acquired by the codes used in its design. This article presents a framework to obtain the reliability index of a bridge under seismic events, using response surface method and first order reliability method, based on random variables that affect the structure capacity (pushover analysis) and the seismic loads (peak ground acceleration). The bridge reliability of the case study is updated using visual inspection techniques. Results indicate that the vulnerable zone on the bridge is its shortest pier and the failure could occur due to high shear concentration in the hinge at the bottom of the pier.</p>

scholarly journals Seismic Loss Estimation in Pre-1970 Residential RC Buildings: The Role of Infills and Services in Low–Mid-Rise Case Studies

2020 ◽  
Vol 6 ◽  
Author(s):  
Carlo Del Gaudio ◽  
Maria Teresa De Risi ◽  
Santa Anna Scala ◽  
Gerardo Mario Verderame
Keyword(s):  
Case Studies ◽  
Pushover Analysis ◽  
Economic Loss ◽  
Loss Estimation ◽  
Lessons Learned ◽  
Rc Buildings ◽  
Loss Assessment ◽  
Ground Acceleration ◽  
Masonry Infills

The lessons learned after recent earthquakes have highlighted the key role played by infills and services in damage and loss of Reinforced Concrete (RC) buildings. Their influence in seismic performance and loss estimation of selected RC building case studies is thoroughly analyzed here. The case study selection aims to be representative of existing buildings built in Italy before 1970, and covers a different number of stories and design typologies. The seismic responses of the case-study buildings are numerically analyzed by means of non-linear static pushover analysis (PO) considering a lumped plasticity approach with a quadri-linear flexural response for beam/column elements (properly calibrated for RC elements reinforced with plain bars) and a tri-linear compressive-only axial response with diagonal concentric struts for infill panels (empirically derived from experimental data on hollow clay masonry walls). Economic loss estimation is carried out via a component-based methodology that relies on the main repairing activities and resultant costs required for the refurbishment of infills and services for different damage levels. Accordingly, a damage analysis is performed herein, given the intensity measure, based on a comparison between Interstory drift demand from PO analysis and drift-based fragility functions specific for masonry infills. Loss curves, relating the total building repair cost to peak ground acceleration (PGA), are presented and compared for the analyzed case study buildings to show their trends and quantify the incidence of infills and services with respect to the reconstruction cost. A comparison between these outcomes and those recently found in the literature emphasizes the robustness of the considered approach and the reliability of the hypotheses about damage and loss assessment.

scholarly journals Seismic Assessment of Steel MRFs by Cyclic Pushover Analysis

2019 ◽  
Vol 13 (1) ◽  
pp. 12-26 ◽  
Author(s):  
F. Barbagallo ◽  
M. Bosco ◽  
A. Ghersi ◽  
E.M. Marino ◽  
P.P. Rossi
Keyword(s):  
Local Level ◽  
Pushover Analysis ◽  
Nonlinear Dynamic Analysis ◽  
Structural Response ◽  
Strength Degradation ◽  
Structural Members ◽  
Seismic Behaviour ◽  
Ground Acceleration ◽  
Nonlinear Static

Background:Structural members subjected to strong earthquakes undergo stiffness and strength degradation. To predict accurately the seismic behaviour of structures, nonlinear static methods of analysis have been developed in scientific literature. Generally, nonlinear static methods perform the pushover analysis by applying a monotonic lateral load. However, every earthquake input is characterized by several repeated loads with reverse in signs and the strength and deformation capacities of structures are generally related to the cumulative damage. This aspect is neglected by the conventional monotonic approaches, which tend to overestimate the strength and stiffness of structural members.Objective:This paper aims to investigate the possibility that the Cyclic Pushover Analysis (CPA) may be used as a tool to assess the seismic behaviour of structures. During the CPA, the structure is subjected to a distribution of horizontal forces that is reversed in sign when predefined peak displacements of the reference node are attained. This process repeats in cycles previously determined in a loading protocol.Methods:To investigate the effectiveness of the CPA in predicting the structural response, a steel moment resisting frame is designed as a case study building. A numerical model of this frame is developed in OpenSees. To examine the influence of the loading protocols on the seismic response, the CPA is run following the ATC-24 and the SAC protocols. Additionally, the seismic demand of the case study frame is determined by a Monotonic Pushover Analysis (MPA) and by Incremental nonlinear Dynamic Analysis (IDA).Results and Conclusions:The following results are obtained:• Despite the differences between the SAC and the ATC-24 loading protocols, the CPA applied according to those two protocols led to almost the same structural response of the case study frame.• The CPA showed the capability of catching the stiffness and strength degradation, which is otherwise neglected by the MPA. In fact, given a base shear or peak ground acceleration, the CPA leads to the estimation of larger displacement demands compared to the MPA.• During long (or medium) duration earthquakes, the CPA was necessary to estimate accurately the response of the structure. In fact, at a PGA equal to 1 g, the CPA estimated the top displacement demand with an error lower than 10%, while the MPA underestimated it by 18%.• The importance of considering the cyclic deterioration is shown at local level by the damage indexes of the frame. In the case of long earthquakes, given a top displacement of 600 mm (corresponding to a PGA equal to 1 g), the CPA estimated the damage indexes with an error equal to 12%.

scholarly journals Case Study of a Heavily Damaged Building during the 2016 MW 7.8 Ecuador Earthquake: Directionality Effects in Seismic Actions and Damage Assessment

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 74
Author(s):  
Luis A. Pinzón ◽  
Luis G. Pujades ◽  
Irving Medranda ◽  
Rodrigo E. Alva
Keyword(s):  
Damage Assessment ◽  
Strong Motion ◽  
Response Spectra ◽  
Seismic Action ◽  
Damage State ◽  
Ground Acceleration ◽  
Intensity Measures ◽  
Capacity Curves ◽  
Building Orientation

In this work, the directionality effects during the MW 7.8 earthquake, which occurred in Muisne (Ecuador) on 16 April 2016, were analyzed under two perspectives. The first one deals with the influence of these effects on seismic intensity measures (IMs), while the second refers to the assessment of the expected damage of a specific building located in Manta city, Ecuador, as a function of its azimuthal orientation. The records of strong motion in 21 accelerometric stations were used to analyze directionality in seismic actions. At the closest station to the epicenter (RRup = 20 km), the peak ground acceleration was 1380 cm/s2 (EW component of the APED station). A detailed study of the response spectra ratifies the importance of directionality and confirms the need to consider these effects in seismic hazard studies. Differences between IMs values that consider the directionality and those obtained from the as-recorded accelerograms are significant and they agree with studies carried out in other regions. Concerning the variation of the expected damage with respect to the building orientation, a reinforced concrete building, which was seriously affected by the earthquake, was taken as a case study. For this analysis, the accelerograms recorded at a nearby station and detailed structural documentation were used. The ETABS software was used for the structural analysis. Modal and pushover analyses were performed, obtaining capacity curves and capacity spectra in the two main axes of the building. Two advanced methods for damage assessment were used to obtain fragility and mean damage state curves. The performance points were obtained through the linear equivalent approximation. This allows estimation and analysis of the expected mean damage state and the probability of complete damage as functions of the building orientation. Results show that the actual probability of complete damage is close to 60%. This fact is mainly due to the greater severity of the seismic action in one of the two main axes of the building. The results are in accordance with the damage produced by the earthquake in the building and confirm the need to consider the directionality effects in damage and seismic risk assessments.

Fault-Tree Model for Risk Assessment of Bridge Failure: Case Study for Segmental Box Girder Bridges

2013 ◽  
Vol 19 (3) ◽  
pp. 326-334 ◽  
Author(s):  
Caitlyn Davis-McDaniel ◽  
Mashrur Chowdhury ◽  
Weichiang Pang ◽  
Kakan Dey
Keyword(s):  
Risk Assessment ◽  
Fault Tree ◽  
Tree Model ◽  
Box Girder Bridges ◽  
Box Girder ◽  
Girder Bridges ◽  
Bridge Failure

Pushover Analysis Based on Equivalent Diagonal Springs for the Assessment of the Seismic Safety of Post-and-Beam Timber Buildings Braced with Nailed Shear Walls

2017 ◽  
Vol 755 ◽  
pp. 170-180
Author(s):  
Natalino Gattesco ◽  
Ingrid Boem
Keyword(s):  
Static Analysis ◽  
Pushover Analysis ◽  
Shear Walls ◽  
Nonlinear Static Analysis ◽  
Plastic Behavior ◽  
Ground Acceleration ◽  
Good Reliability ◽  
Equivalent Viscous Damping ◽  
Seismic Safety ◽  
Capacity Spectrum

A method for a simplified modeling of post-and-beam timber buildings braced with nailed shear walls, useful for seismic design purposes, is presented and discussed in the paper. This strategy is based on the schematization of the vertical diaphragms through equivalent diagonal springs with elastic-plastic behavior and allows the assessment of the resisting ground acceleration by performing nonlinear static analysis; the Capacity Spectrum method based on equivalent viscous damping was applied. This nonlinear procedure constitutes a reliable and simple alternative to the linear static analysis using the behavior factor q. The procedures to determine the characteristics of the equivalent elements (stiffness and load-carrying capacity) are based on analytical evaluations, starting from the actual characteristic of shear walls. A comparison between the results of numerical simulation based of more refined and complex models, previously presented by the authors, and this time-reducing, simplified analysis proved the good reliability of the method.

Anaphylaxis in the OR—Causes, Recognition, and Treatment

2018 ◽  
pp. 199-206
Author(s):  
Surangama Sharma ◽  
Lovkesh Arora
Keyword(s):  
Body Mass Index ◽  
Laparoscopic Cholecystectomy ◽  
Operating Room ◽  
Clinical Manifestations ◽  
Preventative Measures ◽  
Common Causes ◽  
Threatening Condition ◽  
Life Threatening ◽  
Elective Laparoscopic Cholecystectomy

Anaphylaxis in the operating room is a life-threatening condition that can evolve rapidly. As an anesthesiologist, it is important to understand the pathophysiology, diagnose the condition, recognize the inciting agent/agents, and manage it appropriately. It is equally important to confirm the diagnosis for preventing a catastrophic event from happening in future. This chapter defines anaphylaxis, discusses the clinical manifestations and most common causes, and describes ways it can be diagnosed. It also considers treatment and preventative measures. The chapter uses a case study of a 55-year-old female, weighing 85 kg and a body mass index of 36 with no other known comorbidities, who is scheduled to undergo elective laparoscopic cholecystectomy.

Risk Assessment of Axially Loaded Single Piles using RSM-based Reliability Method

2006 ◽  
Vol 321-323 ◽  
pp. 1526-1529 ◽  
Author(s):  
Jung Won Huh ◽  
Kiseok Kwak
Keyword(s):  
Linear Interpolation ◽  
Interpolation Scheme ◽  
Monte Carlo Simulation Technique ◽  
First Order ◽  
Surface Method ◽  
Design Variables ◽  
Reliability Method ◽  
Hybrid Reliability ◽  
Single Piles ◽  
Axially Loaded

An efficient and accurate hybrid reliability method is developed to quantify the risk of an axially loaded pile considering pile-soil interaction behavior and uncertainties in various design variables. It intelligently integrates the concepts of the response surface method, the finite difference method, the first-order reliability method, and the iterative linear interpolation scheme. Uncertainties associated with load conditions, material and section properties of the pile and soil properties are explicitly considered. The algorithm is verified using the Monte Carlo Simulation technique.

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