动态法桥梁损伤检测与识别技术面临的挑战

动态法桥梁损伤检测与识别技术是近年来国际土木工程界研究的热点之一。在系统调研的基础上,分析和总结了该项技术在研究与应用过程中所面临的主要问题,同时对其下一步的研究工作提出了相关建议。     

拱桥拱肋钢管混凝土质量的超声波检测

工程检测实例表明钢管混凝土超声法检测是可行的，分析了钢管与混凝土胶结脱空的原因及防止措施。     

桥式混匀取料机液压系统的改造

为了弥补现有桥式混匀取料机机械式传动系统的缺点,根据现场设备工作的特点和要求,提出了改造液压系统的初步方案,并设计了液压系统的原理图,然后利用AMESim软件对系统进行了仿真分析,证明了系统的合理性与可靠性,为下一步对系统进行优化和改进提供了参考。     

外白渡桥船移大修保护工程设计（上）

外白渡桥是座百年老桥，具有历史文化、人文景观和交通工程三重功能。结合外滩地区交通综合改造工程的建设，对桥梁实施“船移大修”保护。本着“修旧如旧“的原则，将上部钢桁架移运至船厂检测大修，并将下部墩台原位凿除重建，取得了良好效果。工程设计充分体现了科学技术和人文艺术的完美结合。     

斜交板桥横桥向位移原因分析及处治措施

针对一座大角度斜交的空心板桥梁出现的横桥向位移等病害，从力学分析的角度分析了该桥产生病害的主要原因。相关调查资料表明，大多数简易支座斜交板桥存在缓慢下滑和平面内转动的现象，其主要原因是横向下滑力和平面内不平衡力矩。据此提出了该桥的加固处理对策，并对今后进行斜交板桥设计和施工提出了建议，以期引起同行对此类型桥梁病害的重视。     

Experimental Characterization and Optimization of Hybrid FRP/RC Bridge Superstructure System

An experimental investigation was performed to assess the performance of a hybrid fiber-reinforced polymer/reinforced concrete bridge system. The full-scale laboratory specimen was representative of an 813?mm (32?in.) wide strip of a completed bridge in San Patricio County, Tex. The specimen was first subjected to static loading prior to casting the reinforced concrete deck. Displacement, strain, and acoustic emission were recorded. After completion of the nondestructive static loading a reinforced concrete deck was cast in the laboratory to represent one unit of the completed bridge. Load was statically applied with several increased load cycles until failure occurred at a load level exceeding 18 times the calculated design load. The results of the static testing indicated that the original design of the hybrid bridge was very conservative. An optimized design of the hybrid bridge was then derived. The static load testing program and the resulting optimized design are described.     

Wavelet domain analysis for identification of vehicle axles from bridge measurements

Bridge weigh-in-motion (B-WIM) is a process by which the axle and gross vehicle weights of vehicles travelling at highway speeds can be determined from instrumented bridges. The traditional method of attaching strain transducers to the soffit of the bridge and placing axle detectors on the road surface has been replaced here by using additional transducers underneath the bridge for axle detection and nothing-on-the-road (NOR). This paper presents a wavelet based analysis of strain signals and shows the efficacy of using wavelets in pattern recognition of these signals. The transformed signals are used to identify axle passage and hence the vehicle velocity and the axle spacing. In addition to numerically generated strains, signals acquired from such a NOR instrumentation of a bridge in Slovenia have been analysed by the method of wavelet transformation to extract axle position information that was not readily detectable using existing methods.     

Evaluation of Effective Width and Distribution Factors for GFRP Bridge Decks Supported on Steel Girders

Glass fiber-reinforced polymer (GFRP) bridge deck systems offer an attractive alternative to concrete decks, particularly for bridge rehabilitation projects. Current design practice treats GFRP deck systems in a manner similar to concrete decks, but the results of this study indicate that this approach may lead to nonconservative bridge girder designs. Results from a number of in situ load tests of three steel girder bridges having the same GFRP deck system are used to determine the degree of composite action that may be developed and the transverse distribution of wheel loads that may be assumed for such structures. Results from this work indicate that appropriately conservative design values may be found by assuming no composite action between a GFRP deck and steel girder and using the lever rule to determine transverse load distribution. Additionally, when used to replace an existing concrete deck, the lighter GFRP deck will likely result in lower total stresses in the supporting girders, although, due to the decreased effective width and increased distribution factors, the live-load-induced stress range is likely to be increased. Thus, existing fatigue-prone details may become a concern and require additional attention in design.     

A knowledge-based system for maintenance planning of highway concrete bridges

This paper presents a knowledge-based system that is used for maintenance planning of highway concrete bridges. The system includes functions for maintenance priority setting among bridges, feasible treatment assessment in each case, and maintenance planning for a bridge stock. Maintenance priorities are set using a scoring model with decision parameters appropriately weighted. Feasible treatments are determined based on bridge condition and other factors that accelerate deterioration. Decisions for maintenance planning result from a linear programming model and are based on priority ranking, cost and effectiveness characteristics of feasible treatments, and existing budget constraints. The system has been successfully evaluated with actual and simulated data.