Failure cracks in reinforced concrete structures in Khartoum District

Abstract

Failure in reinforced concrete elements (Partial or complete collapse) may due to lack in design or in certainties of detailing or due to poor construction, or poor concreting and insufficient curing, or due to poor building materials, such as cement, aggregates and reinforcing steel. Failure in reinforced concrete structures may also due to the movement of foundations or due to excessive vibrations in the neibour-hoods. During the last 10 years (1998-2014) failure in reinforced concrete buildings in Khartoum district has been predominant. The research contained in this paper is a result of a series of scientific case studies regarding failure or at least deficiency in some building complexes in Khartoum district carried by the author during his professional practice through his consultant firm named (Thiga for Engineering Consultants and Experimentation) located in Khartoum. Many buildings (having number of stories range between 7-13 storey) has been studied according to scheduled investigations. It has been found that the major reasons of these failure are duo to poor concreting, slab excessive deflection, excessive cracks in beams, foundation settlement, insufficient design, low thickness of slab, and other reasons. I. Introduction: Cracks may be caused by the external applied load on the structure just like flexural crack, shear crack, other cracks are also occurring independently, for example cracking of restrained members due to concrete shrinkage. Or temperature change, surface cracking of fresh concrete in plastic stage, and surface cracking of new concrete near reinforcing bar. However, the major cracks in concrete structures may be due to lack in design or details, bad instruction. Settlement in foundation or due to the time factor (1). A typical study in Egypt showed percentage comparisons of these factors as shown in Fig. 1 (2).