THE GAP - BETWEEN STRUCTURAL DESIGN AND CONSTRUCTION METHODS

Girish Dravid

Abstract: A structural designer is given a brief in the beginning of his design process in the form of a set of architectural drawings, soil investigation report, and at the most, an indication about the number of additional floors over and above the sanctioned height of the building. Based on this information, the structural designer embarks on an arduous course involving load calculations, element sizing, gravity and lateral load resisting framing ensuring a proper load path, selecting appropriate grades of materials, making computer models, multiple analysis runs, complying with innumerable code requirements, satisfying peer reviewers and sanctioning authorities, preparing complicated reinforcement details and producing a huge pile of drawings to be issued to contractors for execution. In this entire process, he is solving a given problem with a fixed set of assumptions and parameters. The design is valid only if the contractor builds the building exactly as is shown on the drawing and in the details. On the other hand, the contractor prepares his own methodology of construction, most often at the tender stage itself, not having adequately detailed drawings and to satisfy time and milestone targets pre-decided by the project management. The methodology is based on the skills and resources he has - for example, the number of formwork sets, formwork system he is comfortable with or sometimes imposed by the project management, his understanding of the site situation and his perception or mis-perception of the structural configuration. It has been observed that there is often a gap between the parameters assumed for design calculations and how the building is constructed in reality. When the construction of the building is complete, one cannot see a geometrical deviation from the intended structural framework. However, the way it has been constructed, there could be a significant variance between intended behaviour and the actual one. The expected long life of the building can be compromised due to this disconnect. For a high rise building performance, such a situation can prove to be alarming. This paper aims at moving the already known facts into the realm of discussion and beginning a focused movement to bridge the gap

Keywords: Design, Construction, Gap, co-ordination,

DOI: https://doi.org/10.15623/ijret.2016.0532011