大跨径连续刚构桥荷载试验分析

文章以某大跨径连续刚构桥维修加固及荷载试验为例,结合荷载试验结果,分析该桥维修加固的效果。结果表明粘贴钢板和裂缝封闭对箱梁顶板纵向裂缝及腹板非结构性斜向裂缝的维修效果较好,但对箱梁底板横向受力裂缝的维修效果不明显,且结构整体刚度未得到改善,结论可为同类工程提供技术参考。     

A model system for the ex-ante assessment of city logistics measures

This paper proposes a model system developed in order to support ex-ante assessment of city logistics measures. The model system allows us to simulate the choices of each decision-maker involved in the urban freight transport and logistics and to investigate how the policies and the following measures can influence her/his choices.The model system is an open architecture and consists of two levels: commodity and vehicle. The commodity level allows us to analyse the attraction and acquisition movements taking into account the effects due to city logistics policy implementation affecting the end-consumer and retailer/wholesaler/producer (restocker) choices. The freight sold in each urban shop (or in general urban business) is estimated starting from consumption demand and, then, the restocker’s choices for restocking are analysed in depth. The vehicle level focuses on the restocking process and the links between retailer and wholesaler/producer operating in the study area. This level allows us to investigate the impacts of implementing city logistics measures on journey time, timing and path used for restocking the urban retail businesses.     

Characteristics of gas explosion loads and structural responses of blast wall on FPSO

Gas explosions generally cause catastrophic damage to surrounding structures and humans. The application of blast wall can effectively prevent the damage. The uniform explosion load is widely used in assessing structural response, but it cannot represent the non-uniform characteristic of actual explosion pressures. The main contents of this paper are to study the effect of gas cloud characteristics on explosion pressure distribution, and analyze the effect of non-uniform loads on structural responses. The results reveal that the explosion loads have strongly spatial inhomogeneous when explosion scenarios have large sized cloud or long combustion distance. By establishing the overpressure-probability exceedance curves for uniform loading method and distributed loading method, based on the given accident frequency several design loads are determined. The structural responses of blast wall under design loads are assessed based on explosion evaluation acceptance criteria. It can be seen that the use of uniform loading method underestimates the structural response and misjudges the deformation pattern compared to actual explosion loads. Global and local explosion pressures should be considered simultaneously in the design specification. The overpressure-probability exceedance curves for non-uniform explosion pressures are recommended to establish the design load for blast wall.