抄録
Though earlier investigations regarding stress distribution in the compression zone of concrete members in flexure have dealt with the problems in the limited range of extreme fiber strain from zero to the ultimate flexural strain of about 0.003, it is essential in studying the post-crushing behavior of reinforced concrete beams to know the properties of concrete stress block under the excessive flexural strain beyond the ultimate value.
The eccentrical compression test, similar to Hognestad's method, were carried out on normal-weight and light-weight aggregate concrete, in which emphasis was laid on obtaining the descending branch of resultant force in the compression zone versus extreme fiber strain diagram. Variables in this experimental investigation were type of aggregate for concrete and strength of concrete. The test results show that the coefficients k1k3 and k2, related to magnitude and position of resultant force, can be obtained continuously with the increase of extreme fiber strain beyond the ultimate value if the loading condition is adequate to control the sudden release of strain energy. The complete stress-strain curves derived from the eccentrical compression tests are presented and compared with the stress-strain curves obtained from the control cylinder tests. The influences of the shape of compression zone on the properties of stress block are also discussed.
The results are quantitatively applicable to analysing the behavior of reinforced concrete flexural members near failure.
