Stress Monitoring And Analysis Of Large-cantilevered Pier Caps During Staged Construction

The construction of Ping-men viaduct has promoted the urban transport development inZhang-jiakou city. The most significant characteristics of this project, is the application ofstreamlined piers and large-cantilevered pier caps. Firstly, based on Ping-men viaduct, thispaper introduces the definition and calculation principles of deep flexural members in China,the United States, Canada, Europe and New Zealand. It also discusses the mechanicalcharacteristic, failure modes and bearing capacity of deep flexural members. Secondly, thepaper analyzes some problems in the construction of the large-cantilevered pier cap, such asthe beam’s cantilever section collapse in the process of pouring concrete, the end of beamslide for the strand tension, the steel scaffold collapsed when template dismantled, throughcracks in some beams. Thirdly, the article analyzes some normal sensors (resistance straingauges, vibrating wire sensors, Fiber Bragg Grating (FBG) sensor) in bridge inspection andmonitoring sensors, which focuses on the FBG sensors. Finally, the article studies the pressdistribution of the two types of piers (the vertical pier and the Y-shape pier) in constructionand operation stages missing.The calculation of concrete norms of deep flexural member is more conservative thanother country’s from the comparison of norms. The monitoring and analysis of the abovetwo types of piers construction stage shows: the stresses measured at each construction stageare closer to Midas Civil calculated values, the latter is about10%larger than the former,while the Midas FEA calculation values are about20%larger than the measured valuesmissing. But for detailed analysis, which should use entity finite element calculation. Typicalcross section principal tensile stress in the solid model standard value is greater than thetensile strength of concrete, but cracks were not found in the corresponding position, thisprobably due to the reinforced bars in beams and piers play a major role. The FBG sensors areeasily affected by temperature, so parameters should be tested before use. In stress analysisstrand tension is recommended as the starting point of the stress measurement. To the beamdisplacement analysis in each construction stage, the measured values are consistent with the theoretical values.Ideas and proposals from this paper have been successfully applied to this viaduct project,which have consequently achieved social and economic benefits. The research findings couldprovide references for the implementation of similar projects.