钢筋混凝土圆形截面非均匀配筋的图算法

圆形截面是工程中常使用的截面形式之一,但圆形截面的配筋计算较为困难,存在双重非线性(材料和截面宽度变化的非线性),《混凝土结构设计规范》给出了计算均匀配筋的超越方程组,且须迭代求解,无法手算.另外,一些圆形截面构件(如桥墩、桩基的预制桩和灌注桩等)的截面尺寸大,构件长,钢筋用量大,若采用均匀布置的配筋方式,中性轴附近的钢筋应力小,强度利用率低,经济性差.若采用非均匀配筋,在远离中性轴的外围区域布置受力钢筋,可大幅节省钢筋用量,且能充分利用钢筋及混凝土的强度.为此本文通过应变计算应力,再计算出内力的方法推导计算圆形截面配筋的公式,并将计算结果绘制成了能计算配筋的无量纲诺模图,由此可快速手算配筋,该图通用性强,可用于任意直径大小及C50以下的混凝土强度等级,是一能快速计算配筋的实用工具.

Graph algorithm for non-uniform reinforcement of circular section of reinforced concrete

A circular section is one of the section forms of a structural member used in engineering,but it is difficult to calculate the reinforcement of a circular section,which has double nonlinearity (the nonlinearity of material and section width variation).The "Code for Design of Concrete Structures" only gives the transcendental equations for calculating the uniform reinforcement,which must be solved iteratively and cannot be calculated manually.In addition,some members with circular cross-section (such as piers,prefabricated piles and cast-in-place pile of pile foundation,etc. ) have usually large cross-section size,length and large area of the reinforcement.If the uniform reinforcement is adopted,the stress of the reinforcement near the neutral axis is small and its strength cannot be fully and economically used.If a non-uniform reinforcement is used,the area of reinforcement can be greatly saved and the strength of reinforcement and concrete can be fully used.In this paper,stresses are calculated by strains and then the internal forces are calculated to derive the formula for calculating the circular section reinforcement.Finely a dimensionless nomogram to calculate the reinforcement is drawn.By using the nomogram,the reinforcement can be calculated quickly by hand.The diagram has strong universality and can be used for any concrete strength below C50 and any diameter of the cross-section.It is a practical tool for quick calculation of the reinforcement.