纵横梁拓宽加固既有T梁桥的参数分析

Parametric Analysis of Widening Stringers and Floor Beams to Strengthen Existing T Beam Bridge

为了指导既有T梁桥纵横梁拓宽加固设计,确定最优参数,以一座跨长20m、桥面宽6m的T梁桥拓宽加固为背景,建立T梁桥纵横梁拓宽加固主梁(拓宽后桥面宽9m)计算模型,对新建横梁的数量及位置、新建纵梁与横梁的刚度、新旧基础间相对沉降量等进行了参数分析。结果表明:对于跨长20m、桥面宽6m(拓宽后宽9m)的T梁桥,在跨中设置1道横梁较适宜;新建横梁的刚度越大,结构的整体性越好,但随着横梁刚度增大横梁自重增加,横梁的最佳截面尺寸为60cm×30cm;随着纵梁高度的增大,结构的最大挠度减小,旧主梁的最大弯矩减小,新主梁的弯矩增大,新建纵梁高度取250cm为宜;新旧基础间的相对沉降对结构支点截面T梁翼板根部受力影响较大,需采取有效的措施来减少相对沉降。

To direct the retrofit design of existing T beam bridge by widening the stringers and floor beams and determine the optimum parameters,the widening retrofit of a T beam bridge,with span length of 20 mand bridge deck width of 6m,was taken as the study background.The calculation model of widening stringers and floor beams to strengthen the main beam of T beam bridge was established（the deck will be widened to 9 m）.The parameters,such as the amount of the newly-added floor beams and their locations,the stiffness of the newly-built stringers and floor beams,the relative settlement amount between the new and old foundations,were analyzed.The results of the analysis show that it is proper to install one floor beam in the midspan of the T beam bridge which has span length of 20 mand the deck width widened from 6mto 9m.Generally,the greater the stiffness of the newly-built floor beam is,the better the integrity of the structure will be.However,as the stiffness of the floor beam increases,its self weight also improves,it is suggested the ideal dimension of the floor beam be 60cm×30cm.As the height of the stringer increases,the maximum deflection of the structure decreases,the maximum bending moment of the old main beam decreases,while the bending moment of the new main beam increases,it is proper to set the height of the stringers at 250 cm.The relative settlement between the new and old foundations will exert remarkable influence on the load bearing capacity of the root of T beam flange plates in the supportive cross section of the structure,and efficient measures should be taken to reduce the amount of relative settlement.