Study of Embedded Collar Head as Shear Reinforcement of High Strength Concrete of Flat Plate With Opening

Abstract

This study displays an experimental investigation on one form of embedded shearhead called( collar head reinforcement) as shear reinforcement and it displays also theefficient uses of different forms of reinforced concrete . Also it displays the  efficient  of existence of opening on punching shear strength of reinforced concrete flat plate. In the present research, ten specimens are tested with dimensions (1000x1000x75 mm) which are divided into two groups; the first group is a normal strength concrete with a compressive strength 30MPa; the second group is  high strength concrete with a compressive strength 60MPa. Each group consists of five specimens, the first specimen is reference specimen R , and second specimen  with opening adjacent to the column but without collar head No 1, and third specimen] with presence of openings adjacent to the column and with collar head reinforcement on both sides of the column towards the  opening (horizontal) No 2, and fourth specimen with presence of openings adjacent to the column and with collar shear head reinforcement on both sides of the column away from the  opening (vertical) No3,  fifth specimen with presence of opening and with collar headreinforcement  in all sides the column  and extend to the opening No 4. The percentage of cracking load to ultimate load capacity was between (40 –48.5)%. By using collar shearhead around the column sides and extended to the opening, the cracking load can be increased to 100%  . In flat plate with opening, the deflection and crack width can be decrease by using collar head around the column and extend to the opening  and by increasing the compressive strength of concrete  of  the section.. The slabs which had openings adjacent to the column but strengthened with collar head, the percentage of the critical section perimeter was between (107.5 – 128.3) % that was reflected to the capability of this type of shear reinforcement(collar head) in compensation the shortfall in the critical section due to the existence of openings..

Keywords: key words, flat plate , high strength , opening

DOI: 10.7176/CER/11-8-05

Publication date:September 30^th 2019