Abstract
Abstract
The research aims at studying the structural behavior of R.C beams having openings (at the shear zone) under repeated loads. The experimental program includes testing 7 R.C beams of (200mm*350mm*2400mm).The beams were divided in to two groups, the 1st.group were used to find out the shape effect, while the 2nd. group was utilized to find out the effect of the opening size (two beams without openings, considered as a reference beams) group one consisted of three R.C beams either with circular openings (dia.150)mm or square opening (133*133)mm or rectangular opening (200*88)mm located in the middle of the shear zone. Group two, consisted of three R.C beams with variable sizes of circular openings ,that is , (100mm , 125mm , 150mm) diameter ..When the results were analyzed , it was noticed that the presence of openings in the beams caused a reduction in the R.C beams strength a mounting to a ratio between (14-50)%, and caused an increase in the deflection of (25.5-39.2)%(relative to the control beam without openings) depending on the shape and size of the opening. From the study of the shape effect, it was found that the beams with rectangular openings had a higher strength than the ones with square openings of (20.4)% and (38.77)% than those of circular openings.When testing three R.C beams with different circular openings , (100mm , 125mm , 150mm ) diameter , the results indicated ,that the beam of 150mm diameter opening suffered a reduction in strength of (50.5)% while the reduction was (23%)and (14%) for the beams with (125mm)diameter and (100mm) diameter respectively .
