| Popis: |
There is ongoing competition in the construction market to develop innovative, safe and functional floor systems to speed up the construction process of midrise and high- rise buildings and make it more economical. Due to the fast track construction demand in large cities and metropolitan areas nationwide, different structural systems have been developed and utilized in both commercial and residential low rise, moderate, and supertall buildings. Different types of structural slab systems are currently used in building floor systems. They include conventional concrete slabs, reinforced concrete flat slabs, hollow core slabs, ribbed slabs, post tensioned concrete slabs, precast concrete framing systems, and structural steel composite stud-girder system. These systems work as rigid diaphragms to transfer lateral forces to the lateral force resisting system in addition to carrying gravity loads. Some of these slab systems require shoring during the construction until slab has gained sufficient strength. Others are only cast-in-place systemsIn this research, an innovative thin-walled open steel box beam with composite concrete deck system was developed. The system is modular and consists of adjacent thin- walled steel beams simply supported on girders, columns, or walls. The system will provide the required strength and stiffness and can be precast or cast-in-place and more economical. Two innovative floor systems were developed in this research: the first one was a lightweight two-way cold formed steel composite deck module and the second system was the thin-walled open steel box beam with composite deck system. After a preliminary study of the two systems, the second system was selected to be the main subject of this research. The system was evaluated for constructability, strength, and serviceability. A numerical tool was used to evaluate strength and serviceability. Design aids were developed using the numerical tool for various box geometries, wall thickness, concrete slab thickness, span length, and live load intensities. A parametric analysis of the various parameters that effect vibration accelerations and stress levels were performed. Cast-in-place and precast construction analysis was also investigated. The open box wall thickness as well as the box height were among the most critical parameters. Span lengths up to 50 ft can be achieved with 3/16 in. wall thickness, 12 in. to 24 in. box depth and a width of 24 in. to 48 in. An analytical investigation of the floor system using 3D finite element analysis with solid elements was conducted. The 3D finite element analysis evaluated walking vibrations and live load deflections using light-weight versus normal weight concrete and cast-in-place versus precast construction. Results from the finite element analysis and from numerical tool using basic principles of mechanics were similar.The intellectual merit of this research focused on understanding the performance of the floor systems in buildings and their efficiency in load resistance, load transfer and vibration mitigation. A broader impact from this research will be providing the building engineering community with an innovative floor system that can be efficient and economical. |
