scholarly journals Seismic Vulnerability Assessment of Skewed Reinforced Concrete Bridges

2021 ◽  
Author(s):  
Amr Ghanem ◽  
Do-Soo Moon ◽  
Young Joo Lee
Keyword(s):  
Reinforced Concrete ◽  
Structural Reliability ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Transportation Systems ◽  
Earthquake Ground Motion ◽  
Skew Angle ◽  
Skewed Bridges ◽  
Reliability Method ◽  
Bridge Models

Skewed bridges are commonly used in highway interchanges where the straight (unskewed) bridges are not suitable. There have been several observations of heavy damage of bridges that have geometric irregularities, especially significant skewness. Such damage severely disrupts transportation systems, leading to substantial economic consequences. Skewed bridges are often inevitable due to the complexity and lack of orthogonality of transportation networks; hence better quantification of the effects of skewness on the bridge performance is a more viable approach than avoiding skewed bridges. This research focuses on the seismic vulnerability analysis of skewed reinforced concrete (RC) bridges. From the straight to highly skewed, various bridge models are created based on design example No. 4 prepared by the US Federal Highway Administration (FHWA). A set of earthquake ground motion records is carefully selected to impose consistent seismic demands on bridges. The fragility relationships for all bridge configurations are derived from the non-linear dynamic response history analysis. A new structural reliability method is utilized to handle the computational challenge in deriving fragility curves, which incorporates the structural analysis and reliability analysis to calculate the failure probability efficiently and accurately with the first-order reliability method (FORM). An attempt is made to parameterize the problem based on the skew angle. It is shown that the skew angle has a direct effect on the seismic vulnerability of RC bridges. The results reported will be helpful for new designs of skew RC bridges.

scholarly journals Seismic Fragility Analysis of 3D Vertical Irregular Reinforced Concrete Structures

2021 ◽  
Author(s):  
Amr Ghanem ◽  
Do-Soo Moon
Keyword(s):  
Reinforced Concrete ◽  
Mass Distribution ◽  
Structural Reliability ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Three Dimensional ◽  
Analytical Models ◽  
Seismic Fragility ◽  
Reliability Method ◽  
Dimensional Models

Because changes in the structure's occupancy significantly affect the mass distribution and the structure's behavior, changing mass distribution might make the building more irregular and vulnerable to seismic ground motions. Many researchers tried to evaluate their seismic vulnerability. Most previous studies used simplified structural representations such as two-dimensional models that could not represent accurate seismic behavior from the coupling between lateral and torsional responses. For space structures with high irregularity, more realistic representations such as three-dimensional models are needed for the proper seismic assessment. To handle the computational challenge in deriving fragility curves, this research utilized a new structural reliability method that incorporates structural analysis and reliability analysis to efficiently and accurately calculate the failure probability with the first-order reliability method (FORM). This study investigates the seismic vulnerability of space-reinforced concrete frame structures with varying vertical irregularities. More representative seismic fragility curves are derived with their three-dimensional analytical models. The significant effect of the structure's vertical irregularity on seismic vulnerability is highlighted.

Parametric study of medium span bridges retrofitted with reinforced concrete jacketing

2019 ◽  
Vol 46 (7) ◽  
pp. 567-580
Author(s):  
J.M. Jara ◽  
O. Montes ◽  
B.A. Olmos ◽  
G. Martínez
Keyword(s):  
Reinforced Concrete ◽  
Parametric Study ◽  
Seismic Behavior ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Limit State ◽  
Highway Bridges ◽  
Main Emphasis ◽  
Seismic Forces ◽  
Bridge Models

Most reinforced concrete (RC) bridges in many countries are medium-span length structures built in the last decades and designed for very low seismic forces. The evolution of seismic codes and the average age of the bridges require the evaluation of their seismic vulnerability. This study assesses the expected capacity, demand and damage of seismically deficient medium-length highway bridges, supported in frame-type piers using dynamic nonlinear methodologies. A parametric study of reinforced concrete retrofitted bridges with RC jacketing was conducted. The non-retrofitted structures are 30 m span simple supported bridges with pier heights in the range of 5–25 m. The main emphasis of the study is the assessment of the jacket parameters’ contribution to the seismic vulnerability of bridges. Particularly, it is quantified how jacket thickness and reinforcement ratio affect the probability of reaching a particular damage limit state. The retrofitted scheme includes three jacket thicknesses and three different longitudinal steel ratios. The results evaluate bridge demands and fragility curves to quantify the influence of RC jacketing on the seismic response of structures and allow to select the best jacket parameters that improve the expected seismic behavior of the bridge models. Additionally, the influence of model hysteresis degradation on the expected damage of retrofitted bridges was also determined.

EFFECT OF SKEW ANGLE ON SEISMIC VULNERABILITY OF RC BOX-GIRDER HIGHWAY BRIDGES

2013 ◽  
Vol 13 (06) ◽  
pp. 1350013 ◽  
Author(s):  
AHMED ABDEL-MOHTI ◽  
GOKHAN PEKCAN
Keyword(s):  
Ground Motion ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Nonlinear Dynamic Analysis ◽  
Highway Bridges ◽  
Skew Angle ◽  
Box Girder ◽  
Skewed Bridges ◽  
Damage States ◽  
Skew Angles

In this study, the seismic vulnerability of post-tensioned reinforced concrete box-girder highway bridges with moderate-to-large skew angles to various levels of ground motion intensity is investigated. The fragility curves are generated by performing incremental nonlinear dynamic analysis (IDA) on the bridges of skew angles of 0, 30, and 60°s. A total of 45 ground motion pairs are considered to develop the fragility curves. The damage states are presented and quantified based on the column rotational ductility and superstructure displacements at the abutments. Furthermore, the fragility curves constructed are compared against those recommended by HAZUS. It is demonstrated that as the skew angle increases, skew bridges become more vulnerable to seismically induced damages. It is also shown that the HAZUS fragility curves may not lead to a consistent prediction of the vulnerability of skewed bridges.

scholarly journals Time-Dependent Reliability Analysis of Reinforced Concrete Beams Subjected to Uniform and Pitting Corrosion and Brittle Fracture

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1820
Author(s):  
Mohamed El Amine Ben Seghier ◽  
Behrooz Keshtegar ◽  
Hussam Mahmoud
Keyword(s):  
Reinforced Concrete ◽  
Brittle Fracture ◽  
Reliability Analysis ◽  
Pitting Corrosion ◽  
Structural Reliability ◽  
Time Dependent ◽  
State Function ◽  
Rc Beams ◽  
Highly Nonlinear ◽  
Reliability Method

Reinforced concrete (RC) beams are basic elements used in the construction of various structures and infrastructural systems. When exposed to harsh environmental conditions, the integrity of RC beams could be compromised as a result of various deterioration mechanisms. One of the most common deterioration mechanisms is the formation of different types of corrosion in the steel reinforcements of the beams, which could impact the overall reliability of the beam. Existing classical reliability analysis methods have shown unstable results when used for the assessment of highly nonlinear problems, such as corroded RC beams. To that end, the main purpose of this paper is to explore the use of a structural reliability method for the multi-state assessment of corroded RC beams. To do so, an improved reliability method, namely the three-term conjugate map (TCM) based on the first order reliability method (FORM), is used. The application of the TCM method to identify the multi-state failure of RC beams is validated against various well-known structural reliability-based FORM formulations. The limit state function (LSF) for corroded RC beams is formulated in accordance with two corrosion types, namely uniform and pitting corrosion, and with consideration of brittle fracture due to the pit-to-crack transition probability. The time-dependent reliability analyses conducted in this study are also used to assess the influence of various parameters on the resulting failure probability of the corroded beams. The results show that the nominal bar diameter, corrosion initiation rate, and the external loads have an important influence on the safety of these structures. In addition, the proposed method is shown to outperform other reliability-based FORM formulations in predicting the level of reliability in RC beams.

Building Seismic Vulnerability Study for China High Rises

2013 ◽  
Vol 353-356 ◽  
pp. 2301-2304
Author(s):  
Fan Wu ◽  
Ming Wang ◽  
Xin Yuan Yang
Keyword(s):  
Ground Motion ◽  
Structural Damage ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Response Spectrum ◽  
Earthquake Ground Motion ◽  
Published Data ◽  
Rapid Urbanization ◽  
High Rise ◽  
Story Drift

High-rise buildings, as a result of rapid urbanization in China, become one of popular structure kind. However, there have been few seismic vulnerability studies on high-rise buildings, and few fragility curves have been developed for the buildings. Based on the published data of more than 50 high rises and super high rises, the structural information such as building heights, mode periods, locations and sites, the maximum design story drift ratios, are collected and analyzed. The vulnerability analysis for high rises uses response spectrum displacement as seismic ground motion input, since the structures have comparatively long natural period. Using statistics and regression analysis, the relationship between the maximum story drift ratio and response spectrum displacement is established. Based on height groups and earthquake design codes, the fragility curves of different performance levels can be developed. These curves can provide good loss estimation of high rise structural damage under earthquake ground motion.

scholarly journals SEISMIC FRAGILITY ASSESSMENT AND RETROFIT OF A GOVERNMENT HOSPITAL BUILDING IN CHITTAGONG, BANGLADESH

2018 ◽  
Vol 30 (1) ◽  
Author(s):  
Md. AbulHasan ◽  
Md. Abdur Rahman Bhuiyan
Keyword(s):  
Ground Motion ◽  
Return Period ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Response Spectrum ◽  
Seismic Fragility ◽  
Earthquake Ground Motion ◽  
Type I ◽  
Type Ii ◽  
Ground Motion Records

Chittagong Medical College Hospital (CMCH) is one of the most important government hospitals in Bangladesh. It is located in the heart of Chittagong city, the only port city of Bangladesh. Bangladesh National Building Code (BNBC) is the only official document, which has been used since 1993 as guidelines for seismic design of buildings. As per the guidelines of BNBC, the CMCH building was designed for an earthquake ground motion having a return period of 200 years. However, the revised version of BNBC has suggested that the building structures shall be designed for an earthquake ground motion having a return period of 2475 years. It is mentioned that a single seismic performance objective, the life safety, of the building is considered in both versions of BNBC. Considering the significant importance of CMCH building in providing the emergency facilities during and after the earthquake, it is indispensable to evaluate its seismic vulnerability for the two types of earthquake ground motion records having return period of 200 (Type-I) and 2475 (Type-II) years. In this regard, this paper deals with the seismic vulnerability assessment of the existing ancillary building (AB) of CMCH. The seismic vulnerability of building is usually expressed in the form of fragility curves, which display the conditional probability that the structural demand (structural response) caused by various levels of ground shaking exceeds the structural capacity defined by a damage state. The analytical method based on elastic response spectrum analyses results is used in evaluating the seismic fragility curves of the building. To the end, 3-D finite element model of the building subjected to 18 ground motion records having PGA of 0.325g to 0.785g has been used in theresponse spectrum analysis in order to evaluate its inter-story-drift ratio (IDR), an engineeringdemand parameter (EDP) for developing fragility curves. The analytical results have shown thatstructural deficiencies exist in the existing ancillary building (AB) for the Type-II earthquakeground motion record, which requires the building to be retrofitted to ensure that the existingancillary building (AB) becomes functional during and after the Type-II earthquake groundmotion record.

scholarly journals Evaluating seismic reliability of Reinforced Concrete Bridge in view of their rehabilitation

2018 ◽  
Vol 149 ◽  
pp. 02043
Author(s):  
Hasnae Boubel ◽  
Oumnia Elmrabet ◽  
Mohamed Rougui ◽  
Ouadia Mouhat ◽  
Echebba EL Mehdi
Keyword(s):  
Reinforced Concrete ◽  
Seismic Vulnerability ◽  
Polynomial Regression ◽  
Limit State ◽  
Concrete Bridge ◽  
Seismic Reliability ◽  
Reinforced Concrete Bridge ◽  
Applied Loading ◽  
Reliability Method ◽  
Bridge Reliability

Considering in this work, a simplified methodology was proposed in order to evaluate seismic vulnerability of Reinforced Concrete Bridge. Reliability assessment of stress limits state and the applied loading which are assumed to be random variables. It is assumed that only their means and standard deviations are known while no information is available about their densities of probabilities. First Order Reliability Method is applied to a response surface representation of the stress limit state obtained through quadratic polynomial regression of finite element results. Then a parametric study is performed regarding the influence of the distributions of probabilities chosen to model the problem uncertainties for Reinforced Concrete Bridge. It is shown that the probability of failure depends largely on the chosen densities of probabilities, mainly in the useful domain of small failure probabilities.

Seismic Analysis for the Structural Retrofit of “Palazzo della Civiltà Italiana” in Rome EUR, Italy

2010 ◽  
Vol 133-134 ◽  
pp. 753-758
Author(s):  
Tomaso Trombetti ◽  
Claudio Ceccoli ◽  
Giada Gasparini ◽  
Stefano Silvestri
Keyword(s):  
Reinforced Concrete ◽  
Structural Reliability ◽  
Seismic Vulnerability ◽  
Seismic Analysis ◽  
Structural Safety ◽  
Reinforced Concrete Structure ◽  
Construction Technique ◽  
Non Invasive ◽  
Original Configuration

The “Palazzo della Civiltà Italiana” is a monumental building characterized by a reinforced concrete structure composed of parallel (cast in situ) portal frames and composite (reinforced concrete + hollow bricks floors which spans between adjacent portals: a common construction technique in Italy. The floors being characterised by a large span of about 10.0 meters. The construction took place between 1939 and 1943, most likely according to the Italian building code published in 1939. The authors have coordinated a comprehensive experimental campaign aimed at (a) the identification of the characteristics of the structural materials and members, and (b) the identification of eventual damages. Based upon the experimental results a number of analytical and numerical investigations have been developed in order to assess the structural reliability of the “Palazzo” which up to date still is remains in its “original” configuration, as no substantial intervention of structural retrofit or rehabilitation have been implemented so far. These analysis allowed to identify two major reliability issues: (i) the load bearing capacities of the floors do not allow the intended use, and (ii) the seismic vulnerability of the building does not satisfy the reliability standards required by current codes. On the basis of all data acquired and investigations performed, a simple (non invasive) structural retrofit solution capable of bringing the “Palazzo” to the level of structural safety required by current codes is identified.

Effect of damage limit states on the seismic fragility of reinforced concrete frame-shear wall buildings

2021 ◽  
Vol 14 (9) ◽  
pp. 57-68
Author(s):  
Durga Mibang ◽  
Satyabrata Choudhury
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Analysis ◽  
Seismic Vulnerability ◽  
Design Method ◽  
Fragility Curves ◽  
Nonlinear Dynamic Analysis ◽  
Soil Condition ◽  
Shear Wall ◽  
Reinforced Concrete Frame ◽  
Limit States

Assessment of the seismic vulnerability of frame-shear wall buildings can be performed by non-linear dynamic analysis and it needs detailed analytical modeling, structural performance measures and various earthquake intensities. The codal based design method can hardly be used for designing buildings of pre-defined target objectives whereas the Unified performance-based design (UPBD) method can be designed for buildings of pre-defined target objectives. In the current study, the UPBD method for frame-shear wall buildings has been applied for different performance levels (PL) i.e. Immediate occupancy (IO), Life safety (LS) and Collapse prevention (CP) with 1%, 2% and 3% drift in both the directions of the buildings. The nonlinear dynamic analysis of the reinforced concrete (RC) frame-shear wall buildings is performed considering spectrum compatible ground motions (SCGM) as per EC-8 demand spectrum at 0.45g level and type B soil condition. Vulnerability assessment of the frame-shear wall buildings is conducted by generating fragility curves and the probability failure of structure is checked based on different configurations and damage limit states of the structure. Finally, the outcome of the work gives a proper idea of the nonlinear behavior of the dual system so that optimum design could be acquired for achieving higher safety aspects.

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