林聪悟-直线法在基于美国混凝土规范设计中的程序实现

首先,阐述了美国ACI318-08规范中钢筋混凝土受弯、受压构件的设计原理和基本假定。与我国混凝土结构设计规范不同,ACI318-08规范是根据构件的受力破坏形态来确定名义抗压和抗弯承载力的折减系数的,相对于延性破坏,脆性破坏构件的承载力折减较多。然后,由平衡条件、平截面假定及Newton迭代格式,推导出林聪悟-直线法的计算公式。编制程序实现该算法时,须根据最大、最小配筋率的规定对迭代区域进行限定;在确定P-M相关曲线上的拐点位置的基础上,实现中性轴高度在曲线上的分段迭代。通过在曲线拐点处设置微小增量及自动调整中性轴高度等方法,解决了程序计算时可能出现的迭代发散问题。算例表明,所编制程序的计算结果具有很高的精度。

Computer Programming of Tsung-wu LIN Linear Method in American Reinforced Concrete Design Code

The paper firstly expounds the design principles and fundamental assumptions of flexural and compressive reinforced concrete members in Building Code Requirements for Structural Concrete (ACI318-08). Different from Chinese design code of concrete structures, ACI318-08 determines the reduction factor of nominal compressive and bending capacity according to the member' s stress failure mode. The degree of a member's capacity reduction in the brittle failures is greater than that in the ductile ones. Then a calcu-lation formula of Tsung-wu LIN linear method is proposed on the basis of the equilibrium condition, plane section assumption, and Newton's iterative method. In computer implementation of the algorithm for the formula, limitation of iterative region according to the maximal and minimal reinforcement ratio is neces-sary; in addition, the location of inflection points in P-M Relative Curves should be determined in order to realize the respective iteration of the neutral axis height in the curve. Through the establishment of small increment in curve' s inflection points as well as the automatic adjustment of the neutral axis height, the possible iterative divergence problem of Tsung-wu LIN linear method in computer programming is solved. The results show that numerical solutions from the computer program are of high precision.