Measuring Instantaneous Resilience of a Highway Bridge Subjected to Earthquake Events

2021 ◽  
pp. 036119812110095
Author(s):  
S. Hooman Ghasemi ◽  
Ji Yun Lee
Keyword(s):  
Network Performance ◽  
Failure Modes ◽  
Fragility Curves ◽  
Highway Bridges ◽  
Load Path ◽  
Computationally Efficient ◽  
Reliability Indices ◽  
State Highway ◽  
Robustness Measure ◽  
Earthquake Event

Bridges in a road network play a significant role in supporting the flows of people, goods, and freight during an earthquake event and are expected to maintain their functionality following the event. Thus, measuring the capability of a bridge immediately following an earthquake event is critical for understanding the post-earthquake functionalities of transportation networks and supply chain systems involving highway bridges. To this end, this paper proposes a new metric for measuring the resistant capacity of a highway immediately following an earthquake event, which is here called instantaneous resilience. The proposed metric first compares the reliability indices of a bridge before and following an earthquake event to measure the immediate earthquake impact. Although this comparison (i.e., robustness measure in this paper) indicates the remaining strength of the bridge subjected to a given earthquake event, it does not reflect collapse failure modes appropriately. Therefore, the proposed instantaneous-resilience metric combines the robustness measure with the structural redundancy measure to consider various scenarios of load path distribution. The proposed metric is computationally efficient because, in the process, it utilizes a generalized reliability-intensity (R-I) surface of a bridge which can be used to calculate the pre- and post-earthquake reliabilities of any bridge designed based on the American Association of State Highway and Transportation Officials (AASHTO) load and resistance factor design (LRFD). Without developing bridge-specific fragility curves and performing structural analysis of a bridge, the proposed measure enables engineers to make a preliminary assessment of the immediate impact of the earthquake on bridges on a quantitative basis. The step-by-step calculation process of the proposed instantaneous-resilience of a bridge is presented, and its potential use in highway network performance assessment is illustrated with a simple hypothetical network system.

Evolution of seismic design codes of highway bridges in Chile

2021 ◽  
pp. 875529302098801
Author(s):  
José Wilches ◽  
Hernán Santa Maria ◽  
Roberto Leon ◽  
Rafael Riddell ◽  
Matías Hube ◽  
...  
Keyword(s):  
Seismic Design ◽  
Failure Modes ◽  
Highway Bridges ◽  
Design Codes ◽  
Seismic Codes ◽  
Analysis And Design ◽  
Residual Displacements ◽  
Shear Keys ◽  
Maule Earthquake ◽  
2010 Maule Earthquake

Chile, as a country with a long history of strong seismicity, has a record of both a constant upgrading of its seismic design codes and structural systems, particularly for bridges, as a result of major earthquakes. Recent earthquakes in Chile have produced extensive damage to highway bridges, such as deck collapses, large transverse residual displacements, yielding and failure of shear keys, and unseating of the main girders, demonstrating that bridges are highly vulnerable structures. Much of this damage can be attributed to construction problems and poor detailing guidelines in design codes. After the 2010 Maule earthquake, new structural design criteria were incorporated for the seismic design of bridges in Chile. The most significant change was that a site coefficient was included for the estimation of the seismic design forces in the shear keys, seismic bars, and diaphragms. This article first traces the historical development of earthquakes and construction systems in Chile to provide a context for the evolution of Chilean seismic codes. It then describes the seismic performance of highway bridges during the 2010 Maule earthquake, including the description of the main failure modes observed in bridges. Finally, this article provides a comparison of the Chilean bridge seismic code against the Japanese and United States codes, considering that these codes have a great influence on the seismic codes for Chilean bridges. The article demonstrates that bridge design and construction practices in Chile have evolved substantially in their requirements for the analysis and design of structural elements, such as in the definition of the seismic hazard to be considered, tending toward more conservative approaches in an effort to improve structural performance and reliability for Chilean bridges.

Vulnerability-Based Design of Sliding Concave Bearings for the Seismic Isolation of Steel Storage Tanks

2016 ◽  
Author(s):  
Hoang Nam Phan ◽  
Fabrizio Paolacci ◽  
Silvia Alessandri ◽  
Phuong Hoa Hoang
Keyword(s):  
Liquid Steel ◽  
Seismic Isolation ◽  
Failure Modes ◽  
Fragility Curves ◽  
Time History ◽  
Probability Of Failure ◽  
Design Parameters ◽  
Economic Losses ◽  
Storage Tanks ◽  
Isolation System

Liquid steel storage tanks are strategic structures for industrial facilities and have been widely used both in nuclear and non-nuclear power plants. Typical damage to tanks occurred during past earthquakes such as cracking at the bottom plate, elastic or elastoplastic buckling of the tank wall, failure of the ground anchorage system, and sloshing damage around the roof, etc. Due to their potential and substantial economic losses as well as environmental hazards, implementations of seismic isolation and energy dissipation systems have been recently extended to liquid storage tanks. Although the benefits of seismic isolation systems have been well known in reducing seismic demands of tanks; however, these benefits have been rarely investigated in literature in terms of reduction in the probability of failure. In this paper, A vulnerability-based design approach of a sliding concave bearing system for an existing elevated liquid steel storage tank is presented by evaluating the probability of exceeding specific limit states. Firstly, nonlinear time history analyses of a three-dimensional stick model for the examined case study are performed using a set of ground motion records. Fragility curves of different failure modes of the tank are then obtained by the well-known cloud method. In the following, a seismic isolation system based on concave sliding bearings is proposed. The effectiveness of the isolation system in mitigating the seismic response of the tank is investigated by means of fragility curves. Finally, an optimization of design parameters for sliding concave bearings is determined based on the reduction of the tank vulnerability or the probability of failure.

scholarly journals Reliability and protection in distribution power system considering customer-based indices

2021 ◽  
Vol 39 (4) ◽  
pp. 1198-1205
Author(s):  
J.N. Nweke ◽  
A.G. Gusau ◽  
L.M. Isah
Keyword(s):  
Power Supply ◽  
System Reliability ◽  
Distribution System ◽  
Network Performance ◽  
Test System ◽  
Mitigation Strategies ◽  
Reliability Indices ◽  
Electric Power Supply ◽  
Utility Company ◽  
Distribution System Reliability

A stable and reliable electric power supply system is a pre-requisite for the technological and economic growth of any nation. Nigeria's power supply has been experiencing incessant power interruptions caused by a failure in the distribution system. This paper developed a system planning approach as part of the key mitigation strategies for improved reliability and protection of the distribution network. The developed algorithm is tested using 33kV feeder supplying electricity to Kaura-Namoda, Zamfara State,  Nigeria. A customer-based reliability index was used as a tool to evaluate the reliability assessment of the feeder test system. The result showed that alternative 3 gives better results in terms of improvement of the system average interruption duration index (SAIDI), which in turn gives the minimum interrupted energy. Also, it is found that a greater number of sectionalizing switches do not give better results. It is very important to place the sectionalizing switches at a strategic location. If it is located at such points that will facilitate to sectionalize the faulty sections faster and to make the supply available to the unfaulty part of the network. Hence the utility company should apply this mitigation algorithm for system reliability improvement, depending on their needs and requirements. Thus, utilities can optimize network performance and better serve customers by adopting mitigation strategies in addressing trouble-prone areas to achieve a stable and reliable supply Keywords: distribution system; reliability; reliability indices; system performance evaluation; protection system; mitigation algorithms and sectionalizing switches 

HPHT Subsea Connector Verification and Validation Using an API 17TR8 Methodology

2021 ◽  
Author(s):  
Barry Stewart ◽  
Sam Kwok Lun Lee
Keyword(s):  
Failure Modes ◽  
Production Systems ◽  
Three Dimensional ◽  
Full Scale ◽  
Verification And Validation ◽  
Combined Loading ◽  
Load Path ◽  
Capacity Curves ◽  
Industry Standards ◽  
Full Scale Tests

Abstract Wellhead connectors form a critical part of subsea tree production systems. Their location in the riser load path means that they are subjected to high levels of bending and tension loading in addition to internal pressure and cyclic loading. As more fields continue to be discovered and developed that are defined as High Pressure and/or High Temperature (HPHT) these loading conditions become even more arduous. In order to ensure the integrity of HPHT components, industry requirements for components are setout in API 17TR8. This technical report provides a design verification methodology for HPHT products and some requirements for validation testing. The methodology provides detail on the assessment of static structural and cyclic capacities but less detail on how to assess the functional and serviceability criteria for wellhead connectors. Similarly, API 17TR8 does not include prescriptive validation requirements for wellhead connectors and refers back to historical methods. This paper describes a practical application of the API 17TR8 methodology to the development of a 20k HPHT connector and how it was implemented to verify and validate the connector design through full scale tests to failure. A methodology was developed to meet the requirements of the relevant industry standards and applied to the connector to develop capacity charts for static combined loading. Verification was carried out on three dimensional 180° FEA models to ensure all non axi-symmetric loading is accurately captured. Connector capacities are defined based on API 17TR8 criteria with elastic plastic analysis (i.e. collapse load, local failure and ratcheting), functionality/serviceability criteria defined through a FMECA review and also including API STD 17G criteria including failure modes such as lock/unlock functionality, fracture based failure, mechanical disengagement, leakage and preload exceedance. These capacities are validated through full scale testing based on the requirements of API 17TR7 and API STD 17G with combined loading applied to the Normal, Extreme and Survival capacity curves (as defined by "as-built" FEA using actual material properties). Various test parameters such as strain gauge data, hub separation data, displacements, etc. were recorded and correlated to FEA prediction to prove the validity of the methodology. Further validation was carried out by applying a combined load up to the FEA predicted failure to confirm the design margins of the connector. Post-test review was carried out to review the suitability of the requirements set out in API 17TR8 and API STD 17G for the verification and validation of subsea connectors. The results build on previous test results to validate the effectiveness of the API 17TR8 code for verification and validation of connectors. The results show that real margins between failure of the connector and rated loads are higher than those defined in API 17TR8 and show that the methodology can be conservative.

Seismic Investigation of Steel Pile Bents: I. Evaluation of Performance

2002 ◽  
Vol 18 (1) ◽  
pp. 121-142 ◽  
Author(s):  
Ayman A. Shama ◽  
John B. Mander ◽  
Blaise A. Blabac ◽  
Stuart S. Chen
Keyword(s):  
Seismic Behavior ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Ground Motions ◽  
Highway Bridges ◽  
Companion Paper ◽  
Experimental Program ◽  
Evaluation Of Performance ◽  
The Subject ◽  
Overall Performance

The main objective of this study is to assess the seismic vulnerability of a class of highway bridges existing in certain regions of the eastern and central states, where steel H-piles extends out of the soil to support the pier cap. During severe ground motions, the overall performance of the bridge will be governed by the local performance of the pile-to-cap beam connection. The scope of work was divided into several tasks as follows: (1) a theory was developed to predict the performance of the connection under lateral loading; (2) an initial experimental program was conducted to investigate the seismic behavior of the steel bents; (3) a retrofit strategy is proposed; (4) a second experimental study was carried out to validate the proposed retrofit method; and (5) fragility curves for such structures were developed. This paper deals with the first two tasks of the study. The other three tasks are the subject of a second companion paper (Shama 2002).

Sequential Propagation of Seismic Fragility across Interdependent Lifeline Systems

2011 ◽  
Vol 27 (1) ◽  
pp. 23-43 ◽  
Author(s):  
Isaac Hernandez-Fajardo ◽  
Leonardo Dueñas-Osorio
Keyword(s):  
Network Performance ◽  
Fragility Curves ◽  
Mitigation Strategies ◽  
System Management ◽  
Seismic Action ◽  
Water Network ◽  
Service Networks ◽  
Lifeline System ◽  
Failure Propagation ◽  
Lifeline Systems

Realistic models of service networks must consider the evolution of interactions with external systems to evaluate emergent response effects on individual network performance. This paper introduces a new dynamic methodology for the assessment of systemic fragility propagation across interdependent networks subjected to seismic action that improves existing static methodologies. Interdependencies are discrete, unidirectional relationships between elements of distinct networks, which are able to influence response evolution from transient to steady-state stages. Comparisons of systemic fragility curves results for isolated and interdependent power and water networks display the importance of interdependence strength and density properties. For the test water network, inter-systemic failure propagation increases its connectivity loss by up to 24%, while high interdependence strengths make the median fragility rise up to 56.2%. In contrast, reductions of interdependence density improve the median water fragility up to 81.7%. Insights obtained from this model, and its associated sequential fragility algorithm, reveal complex coupling patterns and interdependence-based mitigation strategies that are essential for lifeline system management.

Assessment of precast stringer highway bridges using mean load method

2006 ◽  
Vol 33 (11) ◽  
pp. 1359-1367 ◽  
Author(s):  
Daman K Panesar ◽  
F Michael Bartlett
Keyword(s):  
Bending Moment ◽  
Highway Bridges ◽  
Design Code ◽  
Reliability Indices ◽  
Dynamic Load Allowance ◽  
Bridge Approach ◽  
Specific Factors ◽  
The Mean ◽  
Axle Loads ◽  
Critical Sections

The mean load method of the Canadian Highway Bridge Design Code is used to evaluate the shear and bending moment reliability of existing precast "type G" stringer bridges in Alberta that date from the late 1950s. The overall stringer population is categorized into distinct subpopulations using bridge-specific factors, including the degree of deterioration and approach span condition, which are readily identified during a brief field visit or from inspection reports. Critical sections to be investigated for reliability resisting shear forces or bending moments are determined. The reliability indices decrease if the reinforcement is corroded or the bridge approach is not smooth, and the reduction of the maximum axle loads permitted by legislation due to these factors is quantified. For bridge subpopulations where the actual reliability index is less than the target value for current legal axle loads, the critical axle load for moment is less than that for shear. Therefore, if flexural distress is not noted during inspection of such structures, they are likely adequate for the actual loading they are subjected to.Key words: corrosion, deterioration, dynamic load allowance, mean load method, reliability, visual inspection.

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