ABSTRACT
For simplicity, the RC section is further assumed to be rectangular and a perfect elasto-plastic stressstrain relationship is assumed for steel bar.
From Fig. 1 the following equations can be obtained:
F f bc A f A f Nc co st st sc sc= − + (1)
F b f x c
⎝⎜ ⎞ ⎠⎟∫ ε0 (2)
M N h A f d A f d
f f f b
+
−
′
β α
( )A A N− + (3)
where fco is the strength of concrete; α is the ratio of average compressive stress to fco; fst and fsc are the stress of the tension and compression reinforcement, respectively; N is the axial force assumed to be constant during flexural bending; and f(ε) gives the stress-strain relationship of concrete. Others are defined in Fig. 1. β*c gives the distance from the
1 INTRODUCTION
The modern flexural design theory for Reinforced Concrete (RC) members was developed based on the comprehensive experimental studies from 1930s to 1960s (Hognestad et al. 1955; Mattock and Kriz 1961). Few theoretical studies based on mathematical modeling (Kriz 1961) and numerical simulations (Kriz and Lee 1960) were reported in the early days.
