Seismic Fragility Analysis Of Typical Bridges In The Republic Of Yemen

Seismic events over the history of ancient Yemen since 1811,which was the strongest in 1982 in the city of Dhamar,which arose to the awareness of engineering sectors of the many defects and gaps that can extend from the bridges of highways that have been established.However,this awareness and concern were not until 1990 after the unification of Yemen,where it exceeded the seismic regions in Sana'a and settled on moderate seismic regions such as Central and Southeastern of the Republic of Yemen(CSRY).This relatively long neglect of seismic issues related to bridges in these temperate seismic zones led to the existence of a series of bridges with many deficiencies in seismic design salaries that must be evaluated and processed in order to serve longer and more efficiently.Recently,an emerging decision tool has become increasingly popular in seismic risk assessment studies,known as seismic fragility curves.The Five model bridge types are identified as the CSRY as:-The objective of this study is to improve an exciting methodology for the development of analytical seismic fragility curves for bridge classes that are typical of the Central and Southeastern Republic of Yemen(CSRY)area.Although there are some studies to develop the curves of fragility,the majority focused on the typical bridge classes of the high seismic zones in the Western RY and Syria.More focus is now being placed on CSRY because of the recognition of the potential for the significant ground shake.To help assess the seismic hazard of the region,five typical bridge classes were selected for the development of seismic fragility curves as:1-Multi-Span Supported Continuous Concrete Girder2-Multi-Span Supported Continuous Steel Girder3-Multi-Span Supported Continuous Slab4-Multi-Span Supported Continuous Concrete Box Girder5-Multi-Span Supported Simply Supported Concrete Girder.These five bridges represent nearly 90% of the over 160,000 highways bridges in the region.Statistics indicate that the majority of these bridges have three spans and are of a regular configuration(i.e.,a little or no skew).The seismic design was not carried out when most of these bridges were built,indicating that there is no seismic detail in most of these bridges.The research in this study adapts some of the existing nonlinear time-history analysis methods to create a more robust and restrictive suite of fragile bridge curves.Specifically,existing methods have been adapted so that the effects of more than one element can be integrated into the bridge in determining the fragility of the system(bridge)In Chapter Three,the seismic hazard in the central and southeastern Republic of Yemen is highlighted.It is seen that while seismic activity in the region is not as frequent as in the western Republic of Yemen,there is a serious cause for concern because of the geological composition of the region.Two suites of synthetic ground motions have been identified to help determine the nature of seismic hazards in the region.The main purpose of this study,which consists of five types of bridges,is the most common and established in the studied area CSRY is the use of analytical methods to generate curves of fragility,so that bridges are subjected to a group of synthetic ground motions that have been developed clearly and sequentially for the region and based on studies conducted in The United States,Australia,and most EU countries.In chapter six I was exploring the impact of different modeling parameters on the responses of bridge types considered in this study.The results of these studies are useful in determining which modeling criteria should be treated in a probability rather than an inevitable approach.This also helps to give a clearer understanding of the parameters that require the most rigorous development of the analytical model.The study of test design,which is a statistical approach,is used to explore the variation in eight specific component responses as a result of a change in the different modeling parameter values.The results of this study may be more stable if there is only one response to the bridge,such as the request for ductility on concrete columns.However,the important parameters for each bridge tend to change from one component to another.This is verified by first evaluating the typical characteristics and details of the target bridges,preferring to view the existing bridge stock and then creating detailed 3-D analytical models.Another point addressed in chapter seven is the selection of an appropriate intensity measure.Contrary to popular belief,the acceleration of the ground peak,compared with spectral quantities,was the most common and most common measure of PSDMs for bridge types in this study.One possible reason for this conclusion is that more than one element is considered,and not all are particularly patient.Ground acceleration peak appears to be less sensitive to this fluctuation in behavior.Then the probability seismic demand models(PSDM)are created using these analyze.The PSD models that have been developed may be of importance to create fragility curves when considering specific levels of damage.As it is through the curves of fragility,show us that the most five categories of bridges that are considered are those bridges that use steel girders,where the most vulnerable bridges seem to be concrete girder bridges,followed by bridges with a single span simply supported girder bridges of the five types.Selection of the ground motion suite plays an important role in calculated fragility values.One reason for this is the difference in frequency content from ground motion suites as shown in Chapter three.The most vulnerable bridges seem to be concrete girder bridges,followed by bridges with a single span supported of the five types.Various sources of uncertainty such as HAZUS and REDARS were selected for study during this study,allowing for their direct implementation in existing seismic risk assessment packages.