May 2013

Avoiding Structural Collapse Hazards: Requirements for Guying, Bolting, Bracing and Welding

Structural collapse of buildings and structures during the erection process has been one of the primary causation factors in many fatalities and disabling injuries. As part of the 2013 Zero Fatality campaign, this article focuses on common activities during steel erection, reinforcing steel installation, and precast concrete erection requiring guying, bolting, bracing and welding to help prevent structural collapse hazards. Following are jobsite photographs illustrating some of the requirements and methods designed to help recognize and avoid potential structural collapse hazards. During the erection of any type of building or structure, it is important to maintain structural stability at all times.

Welding and Bolting Requirement — An important OSHA standard 1926.754(b)(2) states “at no time shall there be more than four floors or 48 feet (14.6 m), whichever is less, of unfinished bolting or welding above the foundation or uppermost permanently secured floor, except where the structural integrity is maintained as a result of the design.”

The photograph above illustrates a typical multi-story structure requiring a substantial amount of welding to be performed on column splices, beam to column moment connections, and other portions of the structure to ensure structural stability during the erection process. The steel erection contractor must provide the necessary manpower to perform welding operations to keep up with the continuation of the steel erection process. Unfinished welding on multi-story structures has attributed to many structural collapse incidents.

Guying and Plumbing Requirements — One of the most important steps to help ensure stability of the structure during the steel erection process is to ensure the installation of guy cables or plumb cables. The OSHA standard 1926.754(d)(1) states: “When deemed necessary by a competent person, plumbing-up equipment shall be installed in conjunction with the steel erection process to ensure the stability of the structure.” The proper size and quantity of plumbing cables and wire rope clamps must be determined by a qualified person and available on the jobsite.

Prior to removing plumbing equipment from the structure, caution should be used to ensure that the structure is adequately bolted and welded to prevent movement in the building. The OSHA Standard 1926.754(d)(3) requires that: “Plumbing-up equipment shall be removed only with the approval of a competent person.” Serious incidents have occurred when the guy cables were prematurely removed to be used on another floor. In many cases, the plumb cables can be installed on the columns prior to hoisting them into final position.

Rebar Column Stability and Guying Considerations — Rebar column collapse and column stability have been a serious safety issue and been the center of controversy on many projects. In an effort to address this safety issue, the International Association, in conjunction with a coalition of industry reinforcing stakeholders, have been aggressively pursuing new OSHA requirements for column stability and specific guying requirements.

Prior to erecting rebar columns, it is important for ironworkers and reinforcing contractors to prepare for rebar column stability that addresses the installation and removal of guying systems. These guying or bracing systems must be designed by a qualified person with the appropriate materials to provide adequate column stability.

Ensuring Formwork Bracing — Adequate bracing and shoring is necessary to prevent formwork collapse, and has been another source of serious incidents involving ironworkers installing reinforcing curtainwalls. Once again, the International Association, in conjunction with a coalition of industry reinforcing stakeholders, have been aggressively pursuing new OSHA standards for formwork stability, and specific inspection requirements pertaining to the contractors responsible for erecting the formwork. Accelerated pour schedules and fast-track projects have often overlooked the important responsibility to ensure that formwork is erected and adequately braced prior to reinforcing steel installation.

Diagonal Bracing Open Web Steel Joist — There are many requirements pertaining to erecting and stabilizing K, LH, and DLH series open web steel joists. Prior to erecting open web steel joists, ironworkers must refer to the OSHA bridging tables or the joist manufacturers requirements. In some cases, all rows of bolted diagonal erection bridging must be installed prior to releasing the joist from the crane hoist line to ensure proper stability. When bolted diagonal erection bridging is required, the OSHA Subpart R – Steel Erection standard requires the following information to be provided:

1. The bridging shall be indicated on the erection drawing;
2. The erection drawing shall be the exclusive indicator of the proper placement of this bridging.

The photograph above shows the ironworkers installing the bolted diagonal erection bridging to joists in a vertical rack system. This rack system was designed to allow several joist to be assembled on the ground to ensure stability and avoid collapse hazards.

Stabilizing Precast Concrete Structures — Prior to erecting structural precast members, the ironworker must receive special training and instruction to maintain stability at all times. Precast concrete members can weigh several tons and require the expertise of a qualified ironworker to safely erect. Plumbing, guying, bracing and welding are some of the primary considerations that must be considered to prevent structural collapse hazards.

The Ironworkers National Training Fund provides specific training and information developed by the Precast Concrete Institute (PCI), considered one of the foremost authorities on the design and erection of structural precast members used in buildings, parking garages and other structures.

Special Bolting Requirements for Pre-Engineered Buildings — There are special stability requirements for erecting pre-engineered metal buildings that are different from typical structural steel buildings. Due to the design of this type of structure, the OSHA Subpart R – Steel Erection standard contains specific requirements that ironworkers must be instructed on prior to erection. One of the OSHA standards requires “50 percent of their bolts or the number of bolts specified by the manufacturer (whichever is greater) installed and tightened on both sides of the web adjacent to each flange before the hoisting equipment is released.” This is an important standard established to help prevent structural collapse during the erection process.

The Importance of Training — The Ironworkers National Training Fund has developed a series of special training modules for apprentices and journeymen upgrading that address the recognition and avoidance of structural collapse hazards during the steel erection, reinforcing steel installation and precast concrete erection. These training courses are offered at our training facilities throughout the United States and Canada.

The “2013 Zero Fatality” campaign will challenge all members to “intervene and prevent unsafe conditions and unsafe acts” in the workplace. Structural collapse is one of the “deadly dozen hazards” leading to fatalities and disabling injuries. I will continue to work closely with district councils, local unions and IMPACT regional advisory boards throughout the United States and Canada to promote the International Association’s “2013 Zero Fatality” campaign by “targeting the deadly dozen hazardous activities that lead to fatalities and disabling injuries.”