🕑 Reading time: 1 minuteStructural failures in concrete structures, a part of human failures, occur as long as man and structure exists. In the past man’s comprehension of the structural response was simple and straight; but in today’ complexity of the man and his structure, the structural failure phenomenon is of a multi-dimensional and multi-disciplinary character. Failure is often stated as the stepping stone to success, but there is a high price to pay in terms of energy, time and money. Nobody wants a failure but yet they occur. Lessons from failures are everlasting, revealing and often shocking. We define failure as the absence of a derived function, goal or objective, mission, task or purpose; failure is the opposite to success and there is no easy way to define each of them.
What is Structural Failures of Concrete Structures?Structural failures refer to the absence of its desired / designed / intended performance, behavior, response under all expected environmental conditions (loads, forces, etc.). There are tension, compression, shear, flexure and torsion failures, occurring singly or in a combined state. The classical notions of factors of safety have undergone tremendous changes giving rise to partial safety factors and limit state factors. There is undoubtedly a great rationale in the stipulation of these factors to design but fabrication, erection and assembly factors to application are left entirely to the field conditions. Material failures in structures are viewed as ductile or brittle failures, or sometime as transition ductile brittle failures. Soil and concrete media have their own unique failure mechanisms. Steel is largely governed by ductile failure. Structural failures of concrete structures often imply large and unwanted deformations, severe honeycombing and cracking with spalling, relative displacement of supports and ultimate collapse.
In a damaged structure, the vexing issues that arise are:
- What is the extent of damage and how to quantify the same as required in the strengthening calculations?
- What has been the rate of decay of the material properties and what realistic values should be assessed for strength assessment at that point of time?
- What is the mode of treatment to be adopted and what is the life span of such treatment?
- What is the cost benefit ratio of salvaging a damaged system?
- What should be the criterion for demolition and how to accomplish the same?