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Lesson B. Building Basics. Courtesy of Craig Allyn Rose. Basic Building Principles. Buildings: Designed to resist forces Gravity, wind, earthquakes, etc. Utilize a variety of materials and styles Change, as do fire and building codes Constructed according to current code
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Lesson B Building Basics
Basic Building Principles • Buildings: • Designed to resist forces • Gravity, wind, earthquakes, etc. • Utilize a variety of materials andstyles • Change, as do fire and building codes • Constructed according to current code • Often not in compliance with current codes
The Superstructure • Superstructure • Distributes or carries the load • Vertical extension above the foundation • Vertical load-carrying systems • Frames, bearing walls, and combinations of both • Horizontal load-carrying elements • Normally parts of floors and roofs • Either wall bearing or frame bearing
Figure B-6 Bearing Wall. Figure S-16 Superstructure.
Load Paths • Transmit vertical load systems to ground • Allow buildings to remain upright • Utilize a “top-down” approach • Loads impose forces within a structural member • Loads and forces produce stresses
Figure B-3 Beams. Figure L-8 Load Path.
Load Paths (cont’d.) • Stresses in materials and structural elements • Tension, compression, shear,and bending • Load paths • May be altered by a variety of forces • Improper or overstressed load paths • Created by both nature and firefighters • Moving building parts • Indicate load path shifts and potential failure • Always consider load paths at all structure fires
Connections • Structural elements are joined at connections • Most common structural elements: • Columns, beams, slabs, bearing walls, and trusses • Other structural elements: domes, arches, shells, cables, and membranes • Connections can fail when overloaded
Classification of Loads • According to how loads are imposed • Live, dead, static, dynamic, impact, concentrated,etc. • According to where loads are imposed • Axial (through the center) • Eccentric (off center) • Torsional (twisting)
Specific Hazards Created by Buildings • Building’s contents, structural elements, and nonstructural elements can burn • Fire load • Includes contents, combustible structural elements, and building materials • Fire • Obeys laws of chemistry and physics • Will travel in vertical and horizontal concealed spaces
Specific Hazards Created by Buildings (cont’d.) • Nonstructural elements: • Finishes, ceilings, HVAC systems, and interior arrangements • Voids conceal building components • Combustible concealed spaces • Cause of many large-loss fires • Penetrations in compartmentalized attics: • Allow heat, smoke, and fire to spread
Figure H-1 HVAC System. Figure V-1 Void.
b a Figure P-5 Penetration.
Features of Hazardous Buildings • Unreinforced masonry walls • Parapet walls • Facades, overhangs, and marquees • Voids and concealed spaces • Unprotected steel and steel bar joists
Figure U-2 Unreinforced Masonry (URM). Figure P-4 Parapet.
Features of Hazardous Buildings (cont’d.) • Unprotected floor and roof support systems • Large buildings without sprinkler systems • Long-span floor and roof support systems • Window and door locations that: • Restrict entry or egress • Allow for fire, heat, and smoke extension • Combustible, non–fire stopped load-bearing elements
Hazardous Conditions in Buildings • Poor condition due to lack of maintenance • Deficiencies in construction • Damage or deterioration to the superstructure • Distorted structural members (sagging, bowing, leaning) • Out-of-plumb columns and walls
Hazardous Conditions in Buildings (cont’d.) • Out-of-level floor support systems • Movement of stationary building components • Rapid changes in: • Heat, smoke, or fire conditions during fire-ground operations
Summary • Buildings, and fire and building codes change • Superstructure • Distributes or carries load • Load paths • Allows buildings to remain upright • Improper or overstressed load paths • May be created by both nature and firefighters • Load paths run through connections • Can fail when overloaded