Huangpu River Bridge of the Reconstruction Project of Jinshan Railway Branch Line in Shanghai is a simply-supported through steel truss girder bridge with span arrangement 4 × 112 m. The main bridge of the bridge was constructed by the cantilever assembling and erection by the aid of temporary supports. Because of risk of the cantilever construction and to ensure the construction safety, the stress, displacement and reaction forces of principal components of the bridge in the construction process were monitored and controlled. The software MIDAS Civil 2006 was used to set up the spatial models and it was found from the comparison and analysis of the field measured and theoretic data that in the construction process, the measured stress ac-quired at most of the measurement points was less than the theoretic stress and could meet the safety requirement. Affected by the local rigidity of the gusset plates, the measured rigidity was about 15% greater than the theoretic rigidity. Under the load case of the longest cantilever con-struction, the measured displacement was less than the theoretic displacement with the maximum tolerance being 10 mm. The reaction forces of all supports were controlled within 3 000 kN and the safety of the temporary supports in the construction process was guaranteed.%上海金山铁路支线改造工程黄浦江特大桥为4×112 m下承式简支钢桁梁桥,主桥采用悬臂拼装十辅助临时支架施工.该桥悬臂施工风险大,为确保施工安全,对主要构件施工过程中的应力、位移、反力等参数进行监控.采用MIDAS Civil 2006软件建立空间模型,通过现场实测数据与理论数据对比分析可知:施工过程中大部分测点的实测应力小于理论应力,满足安全要求；由于节点板局部刚度影响,实际刚度较理论计算刚度大15％左右；在最大悬臂工况下,实测位移小于理论位移,最大偏差达10 m m;所有支撑反力均控制在3 000 kN以内,保证了悬臂施工过程中临时支撑的安全.
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