الفهرس | Only 14 pages are availabe for public view |
Abstract This research is an experimental study in the flexural behavior of self-compacting light weight concrete (LWC) slabs. Seven medium scale slabs were statically tested to failure under a central load. The concrete type, flexural reinforcement ratio, slab’s thickness and statical system were the test parameters. Key results showed that the use of LWC in slabs resulted in most pronounced post-cracking structural degradations, including reduced stiffness until failure at 12.5 and 38 % reduced capacity and deformability, respectively, relative to the normal density concrete (NDC) reference slab. The 2.7 failure to cracking loads’ ratio for the LWC slab violating the minimum reinforcement of the Egyptian code also reflected the possibility of reducing this limit in LWC slabs. The LWC slab’s degradations were similarly overcompensated through either 32.6 or 25 % increased reinforcement ratio or thickness, respectively, where 35.7 % increased capacity was achieved, but at the price of up to 70.8 % further deformability reductions. Much lower increases might therefore result in a similar performance -but less ductile- LWC slab relative to the NDC one; hence, limiting the feasibility of LWC slabs to strength governed applications, where the dead loads’ reductions and benefits would overcome the extra cost of LWC production. Finally, the experimental capacities of the slabs were compared to the ACI 318-2008, BS 8110 – 1997 and the ECP 203 – 2007 code XIII equations for flexural capacity predictions .The results is that all codes are very similar to each other as they are conservative for all slabs except for slabs with higher thickness In addition, less conservative prediction are also shown for LWC slabs compared to NDC slab. The previous gives a preliminary indication that, the influence of the depth and concrete grade parameters should be reduced in the codes equations when dealing with LWC slabs. To fulfill the previously mentioned objectives, this research was divided into the following chapters: Chapter (1) : (Introduction) Is an introduction to this research discussing the importance, the scope and objectives of the research program. Chapter (2) : (Literature Review) Presents a historical background on both lightweight and selfcompacting concrete as well as the definition of LWC and the mechanism of achieving SCC. The chapter further presents a review of the flexural capacity of reinforced concrete slabs. Chapter (3) : (Experimental Work) Contains the experimental test program, the properties of the material used, details of the specimens, the description of the experimental set up, measured devices and test procedure. Chapter (4) : (Test Results and Discussions) This chapter presents the test results of the experiments on slabs including crack and ultimate loads, modes of failure, defections as well as concrete and steel strains. XIV Chapter (5) : (Codes Predication) This Chapter discusses the approaches adopted by three wellknown international building codes for flexural capacity predictions of ACI 318-08 [ACI 2008], BS 8110 – 1997 and the ECP 203 – 2007 where used in the above mentioned predictions. Chapter (6) : (Summary and Conclusions) Presents a brief summary of the thesis and the suggested conclusions. For future studies, several recommendations are also introduced. |