收缩徐变对高速铁路斜拉桥单箱单室混合梁位移的影响及调控OA北大核心CSTPCD

Taking a high-speed railway ballastless track hybrid beam cable-stayed bridge with a main span of 300 meters as the background,Midas/Civil finite element software was used to establish its numerical model,to study the impact of shrinkage creep of bridge towers,deck slabs,box girders and other concrete components on the displacement of main girders,and to put forward the measures for the control of the displacement of main girders.The results indicated that after 10 years of bridge completion,the downward displacement of the mid-span main beam caused by concrete shrinkage and creep totaled 79 mm.The proportion of effects of shrinkage and creep on bridge towers,deck slabs,and box girders during construction were 58％,32％,and 10％,respectively,and during operation were 48％,38％,and 14％,respectively.The primary reason for the downward displacement of the mid-span main beam was the deformation of bridge towers and deck slabs.The shrinkage and creep of concrete shrank the size of the vertical direction of bridge towers and the longitudinal direction of deck slabs and altered the positions of anchorage points and cable forces of the stayed cable,resulting in a downward displacement of the main beam by 56 mm during construction and 18 mm during operation.Raising the cable-stayed bridge towers'anchorage points by 10 mm in advance can eliminate the initial error in steel beam erection caused by concrete shrinkage and creep.Measures such as storing the prefabricated concrete deck slabs for six months,using low-creep concrete for the bridge towers,and delaying track laying by 90 days after bridge completion can improve the adverse effects of concrete shrinkage and creep on the displacement of single-box single-cell hybrid beams.These measures can reduce the downward displacement of the mid-span main beam by 3％to 38％.