BEHAVIOR OF HIGH STRENGTH REINFORCED CONCRETE SLABS UNDER CONCENTRATED AND LINE LOADS

Abstract

High strength concrete (H.S.C) with a compressive strength greater than 420 kg/em 2 is experiencing increased use and acceptance by designers and contractors. However, most of the current design procedures of building codes are based on the experimental investigations obtained from normal concrete with a compressive strength in the range of 200 to 300 kg/em2 • Developing a satisfactory procedure for the design of structures using high strength concrete, needs, additional considerations, validation,

and modification of some recommendation of the existing design building codes.

The objective of this research is to study the behavior of (H.S. Concrete) slabs under the effect of concentrated and line loads. It includes both experimental and analytical studies. The experimental work includes an investigation of twenty two high strength concrete slabs consisted of two main series. The first series (two way slabs) consists of two groups, the first group consists of ten slabs with a rectangularity ratio . equals to one, and the second group consists of five slabs with a -rectangularity ratio equals to 1.5. The second series consists of seven rectangular slabs with a rectangularity ratio equal to 2 simulating one way slabs. The main parameters considered in this study are the slab rectangularity ratio, the type of loading (line load or concentrated load), the slabs effective thickness, the percentages of steel reinforcement, the arrangement of reinforcement, and the eccentricity of the applied loads, The effect of each parameter on the slab deflections, cracking performance, strain distributions in both concrete and steel along the slabs and the slab failure loads are investigated. In addition, an analytical study using a non linear three dimension computer program [ Assembly ] modified by Dr. M .Basil Emara'! 15 1was made . A comparison between test results, and results from the

analytical analysis obtained by the finite element was carried out. Furthermore, a comparison between the analytical and experimental results with some of available current design building codes was made. The applicability of using some suggested modifications for the design of H.S. Concrete slabs was also studied. Within the liinits of the conducted experimental and analytical •studies some additions to code items are proposed to be incorporate in the Egyptian code as a basis for the design of H.S.C slabs.