Diyala Journal of Engineering Sciences (Mar 2021)
Study Effect the Shear Spacing and Width of Beam on Behavour of Reinforced Concrete Wide Beams
Abstract
This paper presented an experimental study of the behaviour of wide reinforced concrete beams with different shear spacing and beam width. Eight specimens in two groups, the group one contains four specimens with the dimensions of (200x500x1600mm) and shear reinforcement spacing (d/2, 0.65d, 3/4d and 1.0d), the group two contains four specimens with the dimensions of (200x600x1600mm) and shear reinforcement spacing (d/2, 0.55d, 3/4d and 1.0d), Variables studied in this study shear reinforcement spacing and width of wide beam, the increasing of shear reinforcement spacing gives close results in RC wide beam, increased shear reinforcement spacing decreased the ultimate loud by 6.6% and when increasing width of beam the ultimate loud decreased by 9.5%, The ultimate deflection decreased by 16.5% and when increasing width of beam decreased by 7.2 %,The number of flexural cracks was equal in all beams, when increasing width of beam the number of flexural crack increased by 2 cracks, The average spacing between shear cracks decreased by 7%, when increasing width of beam average spacing between shear cracks decreased by 19%. Conclusions Increasing the spacing of shear reinforcement from (d/2 in WB1-G1) control beam to (0.65d ,3/4d and 1.0d) in WB2-G1, WB3-G1and WB4-G1 gives close results in RC wide beam when use width to depth ratio 2.5 (width of beam 500mm) (group one) in all the following tests: • The ultimate shear load gives very close value with control beam (spacing d/2), all beams decreased by 4.25%, 6% and 9.5% respectively • the first flexural crack increased by 10.5%, 5.6% and 15% respectively, the first diagonal crack too increased in all beams by 8.5%, 10.7% and 12.7% for respectively. • The ultimate deflection decreased in all beams by average 16.5%. • The width of first flexural crack increased in WB2-G1 by 25% and decreased in WB3-G1 by 33%, and the WB4-G1 give same width with WB1-G1. • The number of flexural cracks was equal in all beams, the number of shear cracks increased in WB2-G1 by one crack and decreased by one crack in WB3-G1 and WB4-G1. • The average spacing between shear cracks increased in WB3-G1 by 13.6% and decreased by 5.7% and 8.5% for WB2-G1 and WB4-G1 respectively compared with WB1-G1 control beam. When increase the width to depth ratio from 2.5 to 3 (the width from 500mm to 600mm) (group two) notice the following: • The increase width in group two give increase ultimate loud by average 14.25% for all beams compared with group one, when increasing the spacing between stirrups in this group WB2-G2 give same ultimate load with WB1-G2 and the WB3-G2, WB4-G2 decreased by 13.5% and 16.6% respectively compared with WB1-G2 control beam. • The increase width in group two It led to the emergence of the first flexural cracks early by average 14.25% for all beams compared with group one, increasing the shear spacing in this group give increased in WB2-G2 and WB4-G2 by 5.9% and 13% respectively and decreased in WB3-G2 by 12.5% compared with WB1-G2,The first diagonal crack in beams of width 600 mm (group two) decreased in all beams by average 41.7% compared with beams of width 500 mm (group one), but whin increasing the shear spacing in this group give decreased in all beams by 1.5%, 23% and 22% for WB2-G2, WB3-G2 and WB4-G2 respectively compared with WB1-G2 control beam. • The increase width in group two give increase ultimate deflection in all beam by average 22.6% except WB4-G2 (spacing 1.0d) decreased by 16.7% compared with beams in group one (width 500mm), increasing the shear spacing in this group give decreasing in ultimate deflection by 27% compared with WB1-G2 control beam. • The increase width in group two give increase in width of first flexural crack by average 32% compared with beams in group one (width 500mm), increasing the shear spacing in this group gives increased for all beams by average 27.3 % compared with WB1-G2 control beam. • The increase width in group two give increase in number of flexural cracks by average 2 cracks, the diagonal cracks increased too by average 2 cracks, increasing the shear spacing in this group gives decreased by 1 crack in WB3-G2 and increased by 1 crack in WB4-G2 and WB2-G2 give same number of crack compared with WB1-G2 control beam and the number of diagonal cracks decreased in WB2-G2 and WB3-G2 by 2 cracks and the WB4-G2 gives same number of diagonal cracks compared with WB1-G2 control beam. • The increase width in group two give increase in average spacing between shear cracks by 14% in WB1-G2 and WB4-G2 and decreased by 13.5% in WB2-G2 and WB3-G2 compared with beams in group one (width 500mm), increasing the shear spacing in this group gives increased by 5% in WB2-G2 and decreased by 25%and13% for WB3-G2 and W4-G2 respectively compared with WB1-G2 control beam.
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