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This paper presents various case studies of examined and calculated live loads on reinforced concrete structures. These case studies accumulated information and data of existing structures about their design live loads and acquired detailed drawings showing the reinforcement in their floor slab sections. The actual occupancy loads that act on the floor slabs were assessed, and the ultimate loads that an individual slab section should be able to support were calculated using the methods recommended by ACI, CP-114, CP-110, and the yield line theory. A reinforced concrete slab panel was also tested to check the validity of the theoretically predicted ultimate loads. The results were compared to find a safety margin and, if necessary, recommend lower live load outlines for cost reduction. The case studies showed that there is sufficient margin to reduce design live loads on the floor slabs of residential buildings, especially in multistory apartment blocks. Moreover, it was found that the live loads, especially on residential buildings, could be decreased to two-thirds of the code values without risking floor overloading. [ABSTRACT FROM AUTHOR]

Nowadays, the utilization of industrial energy, as well as construction waste, is of high concern. The current paper describes a study of the mechanical properties of cement concrete mixes utilizing Rice Husk Ash (RHA) as a cement substitute. The use of such industrial and agricultural by-products has been the focus of waste reduction for economic, environmental, and technical reasons. In this research, the compressive and split tensile strength of concrete was studied through a 15% substitution of cement with RHA with 0.40, 0.45, and 0.50 waterbinder ratios. It has been found that the addition of RHA significantly improves the mechanical properties of concrete for the used water-binder ratios. The ultimate strength in both compressive and tensile strength was observed at a water-binder ratio of 0.50. It has also been observed that as the water to cement ratio increased, higher gains in concrete's compressive and tensile strength were obtained for all curing periods [ABSTRACT FROM AUTHOR]

This experimental study presents the mechanical properties of concrete using lathe steel fiber. The utilization of such fibers in concrete work as reinforcing material could be used for the infrastructural development, ultimately solving the problem of waste and its impact on the environment. The experimental tests were conducted using different percentages of fibers (i.e., 0%, 1%, 1.5% and 2%) by total Concrete volume. Compressive and tensile strengths were determined and compared with conventional plain concrete. Twenty-four cubic and 24-cylinder specimens were prepared and cured for 28 days. The addition of lathe steel fibers increased compressive strength up to 1.5%, whereas further addition of fibers reduced the overall compressive strength. The optimum compressive strength was obtained at 1.5% of lathe steel fiber addition and is 27.4 MPa, 14.71% higher than the control specimens. The maximum tensile strength was also observed up to 1.5% steel fiber addition which is 3.30 MPa and is 4.75% more than the results of conventional concrete. The study showed that the compressive and tensile strengths have significantly improved with the increase in lathe steel fiber. [ABSTRACT FROM AUTHOR]

There are numerous reasons for which concrete has become the most widely used construction material in buildings, one of them being its availability in different types, such as fiberreinforced, lightweight, high strength, conventional and selfcompacting concrete. This advantage is specially realized in highrise building construction, where common construction practice is to use concretes of different types or strength classes in slabs and columns. Columns in such structures are generally made from concrete which is higher in compressive strength than the one used in floors or slabs. This raises issue of selection of concrete strength that should be used for estimating column capacity. Current paper tries to address this issue by testing nine (09) sandwich column specimens under axial loading. The floor concrete portion of the sandwich column was made of normal strength concrete, whereas column portions from comparatively higher strength concrete. Test results show that aspect ratio (h/b) influences the effective concrete strength of such columns. A previously adopted methodology of composite material analogy with some modifications has been found to predict well the capacity of columns where variation in floor and concrete strength is significant. [ABSTRACT FROM AUTHOR]

Compared to conventional concrete, lightweight concrete is more brittle in nature however, in many situations its application is advantageous due to its lower weight. The associated brittleness issue can be, to some extent, addressed by incorporation of discrete fibers. It is now established that fibers modify some fresh and hardened concrete properties. However, evaluation of those properties for lightweight fiber-reinforced concrete (LWFC) against conventional/normal weight concrete of similar strength class has not been done before. Current study not only discusses the change in these properties for lightweight concrete after the addition of steel fibers, but also presents a comparison of these properties with conventional concrete with and without fibers. Both the lightweight and conventional concrete were reinforced with similar types and quantity of fibers. Hooked end steel fibers were added in the quantities of 0, 20, 40 and 60kg/m3. For similar compressive strength class, results indicate that compared to normal weight fiber-reinforced concrete (NWFC), lightweight fiber-reinforced concrete (LWFC) has better fresh concrete properties, but performs poorly when tested for hardened concrete properties. [ABSTRACT FROM AUTHOR]