COMPUTER AIDED DESIGN OF RC JOIST FLOOR SYSTEMS

Abstract

The development in concrete high-rise buildings as well as the floor framing systems has undergone a dramatic change all over the world. Structural floor systems in high-rise buildings are required to provide unobstructed column-free large spaces, which are relatively lightweight without being too deep. RC joist floor system is one of the most popular flooring systems adopted in high-rise building construction which is relatively light in dead weight and can be used for large spans and medium loads. RC joist floor system consists of a series of small, closely spaced ribs and a thin top slab. It gives flexibility in column alignment and arrangement of floor framings by virtue being supported through torsionally stiff beams, commonly referred to as spandrel beams. American code ACI: 318-2000 gives in detail the relevant recommendations with regard to adopting suitable cross-sectional dimensions for RC joist floors. In comparison, the recommendations of 1 5:456-2000 are rather scant and incomplete. In this dissertation, an attempt has been made to analyze and design RC joist floors as per the recommendations of both the codes and the results compared for advantages or otherwise. For this purpose, a program in VISUAL BASIC 6 has been developed and extensively used. The computer software is a general purpose user friendly interactive program. Code provisions of both ACI:318 as well as IS:456 are inbuilt into easily identifiable icons. Floor stiffness is a function of joist cross-sectional size and joist spacing. It is seen that a judicious decision needs to be taken for the joist size and spacing. For higher live load, alternate joist may be avoided to have what is called as Skip-Joist floor