Optimized Use of High Strength Lightweight Concrete and its Impact on Building Behavior
"High strength lightweight concrete (HSLWC) is one of the important research areas in concrete materials and structural engineering. It is desired for different structural applications including slabs and joists in high-rise buildings. In the case of construction using conventional concrete, self-weight represents a significant proportion of the total load of the structure; however, a reduction in the density of concrete would reduce the overall dead load to the foundation that could result in subsequent reduction in construction cost. In addition, this reduction in the dead load could result in a decrease in the cross section of columns, beams, slabs and foundations. Since the load due to earthquake is proportional to the mass of civil engineering structures and buildings, thus reducing its mass decreases its base shear.
Optimizing the performance of concrete was the main objective of this research. This study focused on the benefits of combining both high strength and lightweight properties of concrete. Increasing strength and having less weight at the same time is a big advantage to ensure design of structures in economic way.
Experimental investigations were performed to obtain the best mixture design that match between lighter weight and higher strength. Several trials were conducted to select the optimal mix design. Moreover, some tests were achieved to account for concrete constituents properties.
A complete analysis was done by selecting a high-rise building with shear walls. The Structural Analysis Program ETABS was used for preparation of a Three-Dimensional Model for the building. The Structural Analysis Program SAFE was used for structural analysis and design of slab floors and foundations. Quantities were calculated manually using Excel. The building characteristics in terms of number of stories, geometry of slab, columns and walls spacing and load values for gravity as well as lateral loads due to earthquake were considered. Other features such as supporting systems were standardized. Several models were designed with variable concrete density and strength and the corresponding building's behaviour was studied.
Finally, the results obtained from high strength lightweight concrete and conventional concrete models were compared. The aim of this comparison is to highlight the efficient performance of HSLWC and consider savings related to concrete, steel, formwork and invested areas.
Ghida Bahij Al Hakim
Dr. Ousama Baalbaki, Dr. Adnan Elmasri