09-10-2014, 03:59 PM
This thesis investigates the seismic analysis and design aspects of R.C. frame type elevated water tank staging. Performance of such staging in past earthquakes has been reviewed. The bracing girder of such tanks are particularly vulnerable to shear failure. The Indian code provisions for a seismic design of elevated water tanks have been reviewed. The code provides for rather low seismic design force for these structures due to the absence of a suitable value of performance factor which must be in the range of 2.5 - 3.5. On the other hand the code is too conservative (in most cases) in proposing that the tank be modelle4 as a single degree of freedom system. It is shown that the analysis that assumes the bracing girders to be infinitely rigid for staging stiffness calculation is very inaccurate. Simple approximate procedures have been proposed to estimate the lateral stiffness of tank staging. These are based on the portal frame and the moment distribution methods which have been suitably modified to account for the bracing flexibility and the three-dimensional behavio