中文摘要：

服役年限较长的公路桥梁往往会出现混凝土开裂、钢筋锈蚀、预应力缺损等病害而导致梁体刚度衰减，针对梁体的实际刚度分布状况识别问题，根据材料力学及数值分析相关理论，以梁式结构为例结合位移互等定理推导梁体各区段的实际刚度分布公式。建立三轴车辆与单位荷载在移动过桥时的跨中挠度曲线之间的转换关系，进而凭借三轴车辆低速行驶过桥时采集的跨中挠度时程曲线即可推导梁体实际刚度分布状况，分析全桥病害分布及损伤程度。根据该算法编制配套计算软件。通过桥梁刚度分布识别的算例验证了文中方法的可行性。结果表明，由于损伤原因及程度各不相同，梁体实际刚度分布沿纵向变化较大，不宜采用全梁整体刚度作为桥梁损伤评判标准；文中算法得到的全梁实际刚度分布与实际受损情况吻合良好，该方法可快速、真实、可靠地反映在役桥梁整体损伤状况、锁定损伤范围并估算损伤程唐

英文摘要：

Long service life highway bridges usually suffer from significant damages, such as concrete crack, rebar corrosion and pre-stressed rebar relaxation,which will in turn cause serious stiffness decay of bridge. This paper focused on figuring out the real stiffness distribution in simply supported beams. The material mechanics, numerical analysis, and reciprocal--displacement theorem were employed to deduced the stiffness distribution in each section of the beam. A conversion relationship of the deflection curve at mid-span between 3 axles vehicle and the unit load was established so that by collecting the deflection time schedule curves at the mid span while vehicles move across the bridge at a lower speed, the real stiffness of the beam can be calculated and the assessment of the overall performance of the bridge was also obtained. A compatible software was developed to calculate the stiffness distribution automatically. A case study was conducted to verify the efficiency of the presented method. The experimental results show that the damage degree were different at dif- ferent longitudinal sections. It is inappropriate to use the overall stiffness to evaluate the damage of the whole bridge. The analysis results match pretty well with the calculated stiffness distribution. Thus the proposed method can applicate in engineering practices, such as to predict the stiffness decay,detect the damage area and estimate the degree of damage.