Prestressed Concrete Arch Bridge Structural System Reliability Assessment

A methodology for system reliability assessment of tied-arch bridge was developed in this paper.The methodology combines the use of the response surface method with non-linear finite element analysis.This study aimed to develop the methodology using a representative general-purpose non-linear finite element program,which is widely used in the industry. Initial review study identified the central composite rotatabledesign(CCRD) method as an appropriate method for efficient experiment design within the context of response surface calibration.A study of the loading model was undertaken to develop an appropriate loading model for the system reliability analysis.Existing traffic data were analzed to identify the most frequent Heavy Goods Vehicles and their statisytical data for use in the reliability analysis.Taking a singe span tied-arch bridge as an supportive project example, the element model was developed using 3D beam and shell elements.The failure mode was examined an failure criteria were established.The model was used to perform a sensitivity studys the aim of which was to identify the key parameters that need to be considered as probabilistic variables in the system reliability analysis.Two strength variables and three geometric variables were examined.Results of this study identied the two strength variables and one geometric variable as relatively significant and these were selected for probalistic representation in the subsequent reliability analysis.Initially deterministic analyses wer performed to examine the ultimate system behavior and strength.Three loading arrangements were considered for ultimate strength analyses which included loading the bridge at different locations along the span with two coincident trucks side by side or in lane.The adverse case was selected to perform experiment design and system reliability analyses.Within this case study, the effect of the modeling uncertainty factor of resistance on the system reliability procedure and results was investigated for the simple support tied-arch bridge.Different experiment designs were also analysed to examined the consistency of the system reliability results to the selection of the sampling region.In conclusion a system reliability methodology has been developed and demonstrated in this study for system reliability assessment of tied-arch bridges using the response surface method in conjunction with general-purpose programs for non-linear finite element analyses and reliability analyses.Guidelines for applicationof this method are given.This methodology can be used beneficially in design optimization,re-assessment and maintenance prioritization with significant potentical safety and cost benefits.