斜腹板箱形截面的扭转几何特性

Torsional geometrical properties of box section with inclined webs

根据薄壁箱梁约束扭转理论中的几何特性计算过程,推导斜腹板双室箱形截面的扭转中心、主扇性坐标及主扇性惯性矩的实用计算公式,数值算例验证所推导公式的正确性。以所推导的实用公式为基础,结合数值算例,详细分析斜腹板倾角、悬臂板宽度及梁高等参数变化对斜腹板双室箱形截面的扭转中心、主扇性坐标及主扇性惯性矩的影响规律。研究结果表明:扭转中心至顶板中面的距离随着斜腹板倾角的增大而增大,但该距离与梁高之比却随着梁高的增大而减小;随着悬臂板宽度的增大,悬臂板自由端处的主扇性坐标将显著增大;随着斜腹板倾角的增大,主扇性惯性矩具有先增大后减小的变化规律;当悬臂板宽度较大时,主扇性惯性矩随悬臂板宽度的增大而迅速增大,梁高较大时主扇性惯性矩的增大程度尤为显著。

According to the calculation procedure for the geometrical properties in the restrained torsion theory of thin-walled box girders, the practical formulas for the twist centre, principal sector coordinate and principal sector moment of inertia of a double-ceU box section with inclined webs were derived. Numerical examples validated the correctness of the formulas. Based on the practical formulas derived, the influences of the variations of the web-inclined angle, cantilever plate width and beam depth on the twist centre, principal sector coordinate and principal sector moment of inertia of the double-cell box section with inclined webs were numerically analyzed in detail. The results show that the distance from the twist centre to the middle surface of the top plate increases with the increase of the web-inclined angle; however, the ratio of the distance to the beam depth decreases with the increase of the beam depth. The principal sector coordinate at the tip end of the cantilever plate increases significantly with the increase of the cantilever plate width. The principal sector moment of inertia increases firstly and then decreases with the increase of the web-inclined angle. The principal sector moment of inertia increases rapidly with the increase of the cantilever plate width when the plate width is relatively large; moreover, the increase degree is especially significant for relative large beam depth.