Innovative accessible sunken floor systems for multi-story steel buildings

Abstract

With the demands of telecommunications and computer equipment, building owners and designers are facing an increasingly difficult problem for wire management in today's electronic workplace. This thesis is to investigate and design the accessible sunken floor systems for multi-story steel buildings with proliferating data cables and mechanical equipment. The terminology of an accessible sunken floor system or a dropped floor system is not new. Sunken floor has been used in reinforced concrete buildings with flat slabs and multi-story steel-framed construction with solid wide-flange beams. However, the design of an accessible sunken floor system with open-web steel joists and joist girders is an innovation, by leading steel design and construction industry into a new era. Sunken floors are sirniliar to raised floors, which are composed of removable square floor panels on metal pedestals to provide space for electrical or mechanical equipment or both. The removable panels provide easy access to the equipment below. These floors are commonly used in computer rooms, clean rooms and new office buildings which require extensive mechanical and electrical service. A clean room environment with air return through accessible plenums is essential in microelectronics and pharmaceutical facilities, in hospital operating rooms, in bio-genetic research laboratories and production areas, and in assembly plants for items such as computer disk drives and compact disks. Accessible sunken floor systems are used to avoid ramps or stairs as opposite to raised floor systems. Also, the finished floor-to-floor height in multi-story construction is less than the acceptable height for a raised floor, with subsequent savings on other more expensive building materials. Moreover, the construction cycle for steel buildings with open-web steel joists and joist girders is faster if the finished floor is composed of removable floor panels. One of the proposed systems is to substitute conventional concrete metal decks for fire-rated acoustical ceilings and horizontal bracings to cut down the construction cycle and costs. A second variation of the proposed systems permits economies in concrete slab finish by using lightweight concrete poured on corrugated metal decks, or by using pour- in -place or precast slabs below the finished floor panels, and the floor system is suspended 4 inches below the top chord of the steel joists as a horizontal diaphragm and fire barrier. This thesis will explore the building system integration and forecast the construction cycle and costs. An evaluation of the proposed systems will be presented with matrix diagrams to summarize the conclusion of this paper.