Robustness of Ultimate Capacity for Arch Truss String Structure with Random Ratio of Half-span Load to Full-span Load

摘要

The conventional design method for structural capacity is often based on a fixed load ratio criterion, which lacks sufficient considerations of random properties of load ratio.In this paper, we identify the reliability differences between the fixed and random load ratio criterion for an arch truss string structure under combined full-span load with half-span load.Four different design schemes ate obtained with different measures of strengthening weaker members.Using the finite element method,the relationship is analyzed between capacity and load ratio for each scheme.The capacity result shows that the capacity decreases largely with the increase of half-span load ratio.Then, a more realistic limit state function is bulk for the structures with random load ratio based on a simplified capacity model,and reliability evaluations are performed with the Monte Carlo method.The reliability results indicate that the conventional design method can overestimate the reliability; a design with more uniform capacity and reliability can usually be achieved better by strengthening weaker members.