Cases of faulty anchor bolts and concrete collapses are not unheard of. These materials are used in almost every Massachusetts building, tunnel, bridge, and piece of infrastructure because they can be so secure and durable. However, if improperly constructed, malfunctions can occur that can cause serious injuries or fatalities. Common causes of anchor bolt failures leading to concrete collapses are improperly securing the bolts due to poor training, insufficient supervision of workers, or plain negligence. It is not uncommon for construction workers to skimp on protocol in order to save time and money. Although workers may not realize the amount of damage that can be caused by taking short cuts, lives have been lost due to this kind of carelessness.
Anchor bolt failures can occur during or after construction. Serious injuries can result from these failures such as bleeding, head/back/neck/spinal cord injury, amputation, paralysis, and death. To ensure these injuries are minimized, it is important to adhere to the Occupational Safety and Health Administration guidelines when working with anchor bolts to secure pieces of concrete. Such guidelines include “All columns shall be anchored by a minimum of four anchor rods (anchor bolts)” and “Prior to the erection of a column, the controlling contractor shall provide written notification to the steel erector if there has been any repair, replacement or modification of the anchor rods of that column”. These and other requirements implemented by OSHA are put in place in order to ensure anchor bolts are correctly installed and maintained. Bolts that have been repaired, replaced, or field-modified improperly have been responsible for collapses of concrete slabs and consequent injuries and deaths.
Therefore, proper maintenance of anchor bolts is also crucial to protect the longevity of the components and the safety of bystanders. There are a few types of evaluation procedures to test the integrity of the anchor bolts, both non-destructive testing and semi-destructive testing. The three main techniques typically used are 1) Acoustic impact, in which the bolt is struck by a hammer and the tone determines its condition, 2) Ultrasonic metal flaw detection, essentially passing a mechanical stress wave over the bolt and the way the wave is reflected or transmitted determines the condition of the bolt, and 3) Excavation and discovery, which bolts are cleaned of corrosion and an instrument called a vernier caliper is used to determine the diameter of the bolt. Once these tests have been performed, there are several sub sequential steps that need to be taken. The condition of the anchor bolt determines the next course of action. Possible options following anchor bolt integrity tests include, leaving the bolt alone (if it is in good condition), repairing existing bolts, relocating bolts, or complete anchor bolt extraction and reinstallation. Continue reading