COLLAPE SERCH AND RESCUE OPERATIONS:
TACTICS AND PROCEDURES
Part 4: Interior Shoring-Size-Up and Team Concept
All firefighters should be trained to identify and operate in unstable structural collapse situations. If people are trapped in a collapsed or structurally unstable building, the fire department must act to stabilize the situation and make the structure safe for rescue operations. Shoring procedures will be required.
Rescue shoring is the erection of a series of timbers and bracing to stabilize walls or floors in an attempt to arrest any further movement or collapse of unstable structures that could endanger rescue operations. Rescue shoring is strictly a temporary measure to provide a degree of safety for operating personnel. It is not used to restore structural elements to their original positions or shapes. Any attempt to force beams, columns, sections of walls, or floors back into place may cause a secondary collapse.
There are two basic categories of shoring: interior and exterior. The four most common types of interior shoring are the door or window shore; the vertical or “dead” shore; the rake shore; and the diagonal brace (see illustrations). The door or window shore is used to reinforce and brace existing or new openings in walls; its main purpose is to support loose headers or lintels that may have shifted. The vertical or “dead” shore, the most commonly used interior shore, is used to stabilize floors. The interior rake shore is used to brace out-of-plumb interior walls or columns, transferring the load from the wall to the floor, where the weight is more evenly distributed. The diagonal brace is used to laterally stabilize leaning interior walls, preventing further wall movement.
SHORING SIZE-UP
The initial shoring size-up performed by the shoring officer and firefighters provides a survey of structural damage and victim locations. These are the primary factors in determining the type and placement of shoring. Size-up must be extensive, accurate, and ongoing—the life safety of the rescuers and the victims demands it.
In your survey for victims, ask yourself the following questions: How many victims are trapped? Are there multiple victims or is just one individual buried? Is the information you’re receiving coming from reliable sources, and can it be confirmed? Were there eyewitnesses to the collapse? Are there work supervisors on site to confirm missing personnel? How extensive is the victim entrapment? Is this a localized collapse with only minimal debris, making for a relatively uncomplicated removal, or does the extent of collapse and entrapment dictate a prolonged rescue effort? In general, for rescuers’ and victims’ safety and protection, approach all collapse victim removals as though they require careful, meticulous, extended shoring and void search operations.
In your building survey, consider the following:
- Six-su/ed approach. Survey all four sides and the top and bottom of the collapse area. Surveying the top is extremely important because loose, shifting, or hanging debris or structural elements must be addressed; surveying the bottom is equally important because the shifted loads created by collapse must be transferred to other stable structural members or back to stable ground. Gravity is constant and will try to pull the remains of the building to the earth; so from a shoring standpoint, the bottom survey usually is critical.
- Walls out of plumb. Determine building stability immediately on arrival. Examine the walls in the collapse area. Are they stable or are they leaning in one direction or another? If they are partition or nonbearing walls, will they affect collapse operations in any way? If they are leaning or display signs of having the potential to affect operations, they will have to be shored.
- Bearing walls. The most important structural elements in an unframed building are its bearing walls. They are also the most dangerous factor in a collapse situation, as failure of any part of one of these walls can cause extensive damage and further collapse. Are any sections of the wall damaged or missing? What is the extent of the damage? Is structural stability compromised, or can the wall safely handle its normal capacity? If structural stability is compromised or if there is any doubt concerning the wall’s structural stability, the shoring officer will decide where to shore and how much shoring should be done.
- Strained beams and other structural supporting elements. Floor beams and other structural supporting elements under the main debris pile or under the victim’s location are among the top priorities of site assessment. Beams inherently can withstand large amounts of stress; however, when they are stressed to their limits, very little weight is needed for them to reach the failure point. Any severely bellied, stressed, or cracked beams must be shored up before rescue personnel are committed to the operation.
- Missing structural supports. If any beams, columns, arches, girders, or joists are broken or were knocked down, the building elements they supported must be examined and resupported. In this case, the shoring will take the place of these damaged elements and should be constructed accordingly.
- Structural fire damage. Has the building sustained previous fire damage? The structural stability of an area previously involved in fire must be considered suspect—the integrity of structural elements cannot be relied on for their full bearing capabilities. Shoring may be necessary.
- Age of the structure. Hie age of the building is a shoring size-up factor. The shrinkage of structural elements over time results in a loss of strength and the loosening of important hangers and connecting supports. Older structures with weakened connections and structural elements may require more shoring.
- Condition of the structure. A structure that has received proper, continual maintenance and repair has a better chance of sustaining or surviving a collapse than a building that has fallen into a state of disrepair. Supporting elements of a well-maintained building may be utilized to help support and transfer the collapse load throughout the structure. However, if the building’s condition is suspect, such as in the case of a vacant structure, do not assume there is any structural support without first inspecting the building. The possibility of a secondary collapse in these deteriorated buildings is a primary consideration.
SHORING PLACEMENT
Placement of collapse rescue shoring should be consistent with two main objectives: maintaining the integrity of all structurally unstable elements and properly transmitting or redirecting collapse loads to stable ground or other suitable structural elements capable of handling the additional loads. Consider the following factors in shoring placement.
- One level below any damage. All shoring operations should be started one floor below the level in which structural damage — including stressed beams—has occurred, or at the lowest level, if full-scale collapse has occurred. In smaller buildings such as townhouses, row frames, private dwellings, and smaller attached dwellings or tenements, there are no large interior structural members, and a major collapse generally will require that shoring efforts be started in the basement. In larger framed structures and larger “new law” tenements, collapse may not be complete, as substantial structural elements are capable of supporting and transferring the additional load placed on them. Thus shoring will begin one floor below the damage.
- Support unstable structural elements. The primary structural building supports, such as bearing walls, girders, columns, and arches, should be the first elements examined when rescue shoring is to be erected. These structural members support other structural elements, such as interior walls and floor joists. For example, by shoring a girder, you stabilize more than one section of flooring, effectively utilizing your shoring materials and the existing construction features of the building. After the primary structural supports have been shored up, other localized damage can be examined and shored up if necessary.
- Under the main debris pile. In several collapse types, specifically the V-shaped, supported lean-to, and unsupported lean-to, the majority of debris will settle in one large area—usually on a lower or ground floor. Usually, an extensive and time-consuming debris-removal operation is called for, as the majority of any trapped victims probably will be located in this debris. The subsequent overload of dead weight in this concentrated area will critically strain the existing floor beams and structural elements involved. As a result, the area beneath the load must be examined and shored before any fire department personnel are committed to operations in the debris pile.
- Under victim location. No matter where the victims are trapped, the area around, above, and below them must be examined. If debris removal is to be attempted, the area directly underneath the victim and the operating forces must be shored up. This will ensure a degree of safety’ for the victim and rescue personnel.
- Shores to bear on each other. When numerous areas or floors require shoring, each shore must be erected on solid bearing, or the operation will be self-defeating. In a major collapse of a smaller building with lightweight construction materials, you’ll be starting in the basement. All bearing loads must be transferred to the earth. By shoring the lowest floor, you enable that floor to support a much larger load. Afterward, you can safely start shoring the upper floors. In this way, all additional loads will be directly transferred to the ground.
- From the outside in. In some cases, access to the building may be difficult or remote from the victim location. If so, shoring must be started from the point of entry into the structure. Several sections of shoring may have to be erected to create a safe accessway to the location of the victim(s). It must be substantial enough to withstand a possible secondary collapse, as this pathway usually will remain the primary means of egress from the collapse area.
- Collapse warning signs. A continual surveillance of the structure from several vantage points must be kept from the time of arrival to the time the last rescue personnel have terminated their operation and exited the building. A surveyor’s transit is excellent for detecting any wall movement. Pay particular attention to signs of a possible imminent secondary collapse—shifting debris, airborne dust, sliding plaster, and unnatural sounds (creaking, moaning, groaning) coming from the structure.
THE TEAM CONCEPT
Collapse shoring operations must be conducted safely and efficiently. Generally, the shoring material will not be located in close proximity to the collapse area. This necessitates the formation of two separate teams: the shore assembly team, which will perform the actual shoring size-up and erection of the shores, and the cutting team, which will set up the equipment area and perform the cutting of the shoring lumber.
The shore assembly team. It is recommended that the shore assembly team consist of the shoring officer and two firefighters—the measuring firefighter and the shoring firefighter.
- The shoring officer is in charge of the operation and determines where to place and erect the rescue shoring. His supervision of the shoring operation is based on the shoring size-up, his experience, and department shoring SOPs.
- The measuring firefighter performs all the measuring required in the erection of the shoring, staying in direct contact with the layout firefighter (see The cutting team) via portable radio, and relays all measurements and lumber sizes.
- The shoring firefighter readies the area to be shored by clearing away debris and obstructions that could interfere with constructing the shore, assists the measuring firefighter as needed, and erects the shoring under the supervision of the shoring officer.
The cutting team. The cutting team consists of three firefighters: the layout member, the cutting member, and the equipment member. The initial responsibility of these firefighters is to secure an area as close as possible to the collapse operation so as to minimize the number of personnel needed to relay the materials to the shoring team. It is not unusual to require the help of several companies to expedite the movement of lumber and tools to the collapse area.
- The layout firefighter is in charge of setting up the cutting station and readying the materials to be cut. He/ she handles all measuring and layout of angles. The layout member is in direct contact with the measuring firefighter via portable radio to eliminate problems in miscommunicating measurements of lengths to be cut.
- The cutting firefighter, as the name suggests, cuts the shoring material using appropriate saws/tools assembled at the cutting station. Small chain saws generally are the best tools for cutting shoring members.
- The equipment firefighter handles/supervises the removal of tools and equipment from the apparatus. The apparatus operator generally is designated as the equipment firefighter. Numerous tools from the apparatus will be utilized. The assistance of one or two companies goes a long way in helping get the equipment off the rig and to the right location in a timely manner; the apparatus may be some distance from the area of collapse operations. The equipment firefighter directs assistants with regard to which tools and equipment will be needed and where, and also keeps an inventory checklist/log sheet for easy retrieval of equipment at the conclusion of operations
