永乐大钟梯形木架稳定性初探

对北京市大钟寺悬挂永乐大钟的梯形木架结构的稳定性进行了初步分析. 根据弹性结构稳定性理论的能量法和中国古建筑结构``卯榫'接头抗弯性能的简化的本构模型，采用``对比法'分析了二维梯形木架的结构稳定性；结果表明中国古建筑木架结构的``收分'形状设计对增大木架稳定性有很大作用, 立柱``侧角'越大，稳定性越好. 收分形式设计凸现中国古代工程技术人员的聪明智慧.

A PRELIMINARY ANALYSIS ON STABILITY OF THE TRAPEZOIDAL WOOD RACK OF THE YONGLE BIG BELL

The YONGLE big bell and the wood-rack for suspending the big bell are valuable antique relics. Their safety and reliability have attracted much attention of scientists and engineers.In the present paper a preliminary study on stability of the trapezoidal wood-rack is carried out.Based on a simplified bending constitutive model of the mortise and tenon joint(in Chinese it is called"MAO-SUN")between beams and pillars of the rack,the influence of the side-angle of the pillars on the stability of the rack is analyzed.The energy method of stability theory of elastic structures and the comparison method are used.The formulas for the critical load are derived for the reduced two dimensional trapezoidal rack structures.The critical loads are computed for the wood-rack with different side-angles,as well as for that without side-angle.The results are compared with each other for different racks with different side-angles.It is concluded that the wood-rack with side-angle has better stability as compared to that without side-angle.The wood rack design with inclined pillars is a typical design of wooden architectures in ancient China and shows the wisdom of designers and craftsmen.