重大工程结构在服役期间常遭受各种作用而导致抗力衰减。一旦这些结构失效，将会导致区域功能瘫痪和生态灾难，造成巨大的经济损失和人员伤亡，因此为重大工程结构建立一套健康监测系统具有重要的现实意义。损伤识别是结构健康诊断的核心技术之一，而准确地测量结构的响应信息是损伤识别方法有效的前提。结构荷载的复杂性致使结构损伤具有不可预见性，如果采用电阻应变片技术，其准确性和工程量之大对于工程应用来说是不可取的。采用准分布式长标距光纤布拉格光栅（FBG）应变传感器，并结合其在组合梁中损伤识别的应用以验证其性能。试验结果表明，随着标距的增加，准分布式长标距FBG应变传感器损伤识别的效率降低。

With the construction of a number of massive projects, the structure failure becomes more common and will probably lead to huge economic losses and casualties. It has important and practical significance to establish a complete set of structural health monitoring system for these massive projects. Damage detection is one of the core technologies for structural health identification. Although a variety of damage identification methods have been developed, accurately measuring the response of the structural information is still the premise of the effectiveness of damage identification. Damage in the massive structures cannot be predicted, so it is not advisable to perform health monitoring by means of strain gauges. We use quasi-distributed long-gage optical fiber Bragg grating (FBG), combined with the damage detection application in simply supported steel-concrete composite beam, to verify the performance of such a sensor. The test results show that damage identification efficiency is reduced with the increase in length of the quasi-distributed long-gage FBG strain sensor gage.