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部分预应力砼梁的截面设计,一般需要试算法,这种方法既麻烦又费时。下面介绍的方法适用于全预应力和普通钢筋砼之间的所有范围。象T形、I字形、箱形和矩形截面都可应用。这种方法是在一个简单设计计算中既考虑使用荷载又考虑极限荷载的要求。整个设计只要一张简单的设计图表(图2)和几个简单的公式。图中数据在表1中也可以得到。基本方程可以由相容方程和平衡方程导出。方程的推导类似于钢筋砼设计的允许应力法的推导,并考虑相应的预加应力(附录Ⅰ)。对于极限荷载条件引入两个平衡条件校核,一个用来校核受压翼缘面积的充分性,另一个用来校核预应力和非预应力钢筋
The section design of partially prestressed truss beams generally requires a trial algorithm, which is cumbersome and time consuming. The method described below applies to all ranges between full prestressed and normal reinforced concrete. Like T-shaped, I-shaped, box-shaped and rectangular cross-section can be applied. This method considers the use of both load and ultimate load requirements in a simple design calculation. The entire design requires only a simple design diagram (Figure 2) and a few simple formulas. The data in the figure can also be obtained in Table 1. The basic equations can be derived from compatible and balanced equations. The derivation of the equation is similar to the derivation of the allowable stress method for a reinforced concrete design and considers the corresponding prestressing (Appendix I). Two equilibrium condition checks are introduced for ultimate load conditions, one for checking the adequacy of the compressed flange area and the other for checking prestressed and non-prestressed steel bars.