Diagnostic load testing can be a suitable method for condition assessment of existing bridges. This paper presents the evaluation of a concrete railway bridge built in the 1940s based on diagnostic load testing. The test was the outcome of a visual inspection and preliminary theoretical analysis that found the bridge to be in unsatisfactory condition. Unlike the other possibilities that infrastructure management bodies have in such situations, for example, structure replacement, traffic reorganization, closure of the bridge, etc., diagnostic load testing is a low cost and quick method that indicates the bridge response to real traffic load. The paper describes the test plan and implementation covering the static and dynamic load tests. The experimental methods comprise superstructure displacements measurement, strain measurement on concrete and reinforcement and determination of bridge dynamic parameters. The obtained test results analysis enabled more accurate diagnosis of the actual bridge condition. The bridge demonstrated satisfactory load bearing capacity and response to real service load in terms of registered levels of displacement and strain and proper dynamic performance.

中文翻译：

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通过诊断性载荷测试评估混凝土铁路桥梁的性能

诊断性载荷测试可能是评估现有桥梁状况的合适方法。本文介绍了基于诊断载荷测试对1940年代建造的混凝土铁路桥梁的评估。该测试是目视检查和初步理论分析的结果，该结果发现桥梁状况不理想。与基础架构管理机构在这种情况下可能具有的其他可能性（例如，结构更换，交通重组，桥梁关闭等）不同，诊断负载测试是一种低成本，快速的方法，可指示桥梁对实际交通负载的响应。本文介绍了涵盖静态和动态负载测试的测试计划和实现。实验方法包括上层建筑位移测量，混凝土和钢筋的应变测量以及桥梁动力参数的确定。通过获得的测试结果分析，可以更准确地诊断实际桥梁状况。桥梁在位移和应变的记录水平以及适当的动力性能方面表现出令人满意的承载能力和对实际使用载荷的响应。