在工程实践中，直墙拱应用较多。由于拱脚位移的存在，合理假设拱脚约束为转角约束、竖向约束和水平弹性约束，应用力法推导出了在弯矩、剪力和轴力共同作用下直墙拱沿弧长的弯矩公式。研究了竖向均布荷载、竖向三角形荷载和竖向集中力荷载作用下，直墙拱沿弧长的弯矩分布及反弯点形成的规律；发现在3种荷载作用下，使得拱脚弯矩为零时的圆心角依次减小。取弹簧支座刚度为等效的下端固支、上端允许水平位移的直墙的抗推刚度，得出了随着直墙高度增加，圆弧拱拱顶弯矩增大而拱脚弯矩减小的变化规律。在直墙拱的设计中，建议选取合适的直墙高度和使得圆弧拱拱脚弯矩为零的圆心角大小，从而有利于提高结构抗弯承载力及拱脚抗剪承载力。

Straight-wall arches have been widely applied in civil engineering. Considering displacements at the arch springing, the arch model was assumed as elastically supported horizontally. Distribution of the bending moments was deduced using classical force method. The distribution and the inflection point of the bending moment were studied under uniformly distributed, triangular and concentrated loads, respectively. Central angle corresponding to zero bending moment at the springing was calculated, which decreased when the load changed from uniformly distributed load, triangular load to concentrated load. Horizontal constraint from the side wall was assumed as elastic support and the equivalent spring stiffness was deduced. With the increase of the straight-wall height, bending moment at the crown increased while that at the springing decreased. When the moment at the springing was zero, anti-flexural capacity at the crown and anti-shearing ability at the springing were improved. Straight-wall height and central angle should be selected to make the moment at the springing zero.

国家自然科学基金(51321064、51308544、51478465)；解放军理工大学预先研究基金(KYDXZLXY1301)