中文摘要：

针对桥梁预应力损失计算的复杂性和不易测量性，本文基于光纤光栅传感技术，在一座预应力简支梁跨中埋设光纤光栅应变传感器和静力水准仪，对跨中应变和竖向位移进行了5年的监测，考虑预应力和自重长期作用，对桥梁结构进行变形几何分析和受力分析，建立了简支梁跨中截面应变、位移和荷载之间的关系，提出了预应力简支梁跨中截面预应力损失计算方法。利用桥梁长期实测应变和位移，计算得到成桥四年后桥梁的预应力损失为14．6％。与规范方法计算结果基本一致，验证了该方法的可靠性和有效性。相比规范中的方法，该方法所需参数少，计算简便，且是基于实际桥梁参数，具有一定的准确性；通过在实际桥梁中布设传感器，可对大范围内预应力简支梁预应力损失进行分析，并可实现对简支梁桥预应力变化的长期监测和桥梁健康状态的评估。

英文摘要：

Calculating the prestress loss of a bridge is complex, and the value is difficult to measure. Therefore, the fiber Bragg grating （ FBG） strain sensor and the static level gages are buried in the span of a prestressed simply-supported bridge with FBG sensing technology. The midspan strain and the vertical displacement are measured for five years. Geometrical and mechanical analyses are conducted. Accordingly, the relationship between the midspan strain, vertical displacement, and load is established considering the long-term effects of prestress and dead load. The calculation method for the prestress loss of the cross-section is put forward in this study. The prestress loss of the bridge measured by this method after four years is 14.6%, which is almost similar to the result calculated by the method in the specifications, verifying the reliability and validity of this method. This method needs less parameter and is simpler than the standard methods. The method accuracy can be ensured because the calculation is based on an actual bridge parameter. The prestress loss can be analyzed by placing sensors in the actual bridge. The prestress change can be monitored in a long term. Moreover, the operation state of the simply-supported bridge can be evaluated in a wide range.