WARNING! FIREFIGHTERS ARE FREQUENTLY INJURIED OR KILLED WHEN BURNING STRUCTURES COLLAPSE WITH OUT WARNING

Firefighter Hazards Related to Building Construction The primary objective of understanding building construction and materials is to apply this information to the fireground. Firefighters should use this knowledge to monitor signs of structural instability. These should be reported to the IC ASAP It is everyone’s obligation to constantly monitor for unsafe conditions.

Dangerous Building Conditions There are two primary types of dangerous conditions that may be posed by a building. 1. Conditions that contribute to the spread & intensity of the fire. 2. Conditions that make the building susceptible to collapse.

Terms CONCENTRATED LOAD - Load applied to a small area, example; a/c unit placed on a roof structure DEAD LOAD – The weight of the building materials and any part of the building permanently attached to it. DESIGN LOAD – A load the designer planned for in the building design. UNDESIGNED LOAD – A load not planned for. DISTRIBUTED LOAD – A load applied equally over an area.

FIRE LOAD – All the parts or contents of a building that will burn FIRE LOAD – All the parts or contents of a building that will burn. The amount of heat released from a fuel in lbs\sq ft. LIVE LOAD – The weight of all materials and people associated with but not part of the structure. IMPACT LOAD – a load that is in motion when it is applied. This could be a hose stream striking the side of the building.

Application of Loads AXIAL LOAD – A load padding through the center of the mass of the supporting element, perpendicular to its cross section. ECCENTRIC LOAD - a load perpendicular to the cross section of the supporting element that does not pass through the center of mass. TORSION LOAD – A load parallel to the cross section of the supporting member that does not pass through mass.

Application of Loads Pictures

Loads applied to structural elements as forces COMPRESSION – A force that tends to push materials together. TENSION – A force that pulls materials apart. SHEAR – A force that tends to break material by causing its molecules to slide past each other.

Types of Loads picture

COMMERCIAL BUILDINGS

Building Collapse Knowledge of the type of construction is vital during fire operations because of the possibility of collapse. Some buildings because of their age & construction are more inclined to collapse than others. Buildings that feature lightweight of truss construction will succumb to the effects of fire much quicker than a heavy timber construction. Older buildings that have been exposed to weather & have been poorly maintained are more likely to collapse that well-maintained buildings.

Collapse Zone

Indictors of Possible Building Collapse Cracks or separations in walls, floors ceiling and roof structures Evidence of existing structural instability such as the presence of tie rods & stars that hold walls together. Loose bricks, blocks or stones falling from buildings

Deterioration of mortar between masonry Cracks or separations in walls, floors, ceilings & roof structure

Signs of collapse Deterioration of mortar between the masonry Walls that appear to be leaning Structural members that appear to be distorted Fire beneath floors that support heavy machinery or other extreme weight loads.

Signs of collapse Prolonged fire exposure to the structural members Unusual creaks and cracking noises Structural members pulling away from walls Excessive weight of building contents

Parapet Wall Collapse

RESIDENTIAL COLLAPSE

Parallel Chord Truss

Wood Trusses

Truss Construction Void Spaces

Types of Construction Truss construction Bowstring trusses Wood trusses Open web steel joist Void spaces Engineering wood structural members Roof structures Parapet walls Synthetic materials Fire-resistive and noncombustible construction

WRAP-UP Firefighters must know and understand building construction. There are five common types of construction. Truss construction is dangerous because trusses collapse under fire conditions. Firefighters need to be aware of the hazards associated with structure fires.