Reliability assessment of whole process of incremental launching construction of steel truss bridge
To assess the safety of the incremental launching construction process of long-span continuous steel truss bridge,a combined approach utilizing numerical simulation,statistical investigation,and probabilistic analysis was employed.The entire incremental launching construction process of continuous steel truss bridges from both deterministic and probabilistic perspectives was analyzed and evaluated.Firstly,failure-prone elements throughout the incremental launching process were identified based on combined stress,and their strength and stability were analyzed deterministically,revealing the deterministic safety margin of the incremental launching construction process for steel truss bridges.Secondly,functional relationships for the strength and stability of the failure-prone elements were established,and corresponding reliability indices were analyzed,unveiling the probabilistic safety margin of the incremental launching construction process for steel truss bridges.Lastly,sensitivity analysis was conducted on uncertain parameters affecting the reliability indices,and engineering monitoring recommendations were proposed based on the target reliability indices.The results show that the maximum strength capacity ratio of various members of the main truss during the entire incremental launching process exceeds 60%,with the strength capacity ratio reaching 84.8%and the stability capacity ratio reaching 89.9%at the mid-span location of the main truss during the second-phase paving process,indicating the full utilization of material strength.The maximum strength capacity ratio of the guide beams during the incremental launching process is 29.5%,with a corresponding maximum stability capacity ratio of 41.8%,indicating a significant deterministic safety margin for the guide beams.The reliability indices of failure-prone elements of the main truss and guide beams during the incremental launching construction process are all greater than 5.20,indicating sufficient probabilistic safety margins.During the steel beam closure process,the reliability indices for in-plane stability of the upper chord member A56'A55' and the lower chord member E46'E45' are 3.72 and 2.72,respectively.Material property variability has a significant impact on the reliability indices of members,with the strength and in-plane stability reliability indices decreasing linearly with increasing material coefficient of variation.The combined deterministic and probabilistic analysis results identify key members requiring monitoring throughout the incremental launching construction process.Recommendations for monitoring key members are provided based on target reliability indices,along with displacement and stress monitoring alert values.18 tabs,23 figs,33 refs.
bridge engineeringincremental launching constructionfinite element analysissteel truss bridgereliability assessment