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If an earthquake may have caused damage to a facility, building occupants should be evacuated through pre-established evacuation routes, if they are accessible and clear, to a safe refuge before a preliminary damage assessment is conducted.
Step 1: Survey the Building from the Outside
- Try to determine the structural system (i.e., the skeleton) of the building.
For example: Structural systems are wood studs with plywood sheathing, brick masonry walls, concrete block masonry walls, concrete walls, concrete posts and beams, steel posts and beams, and steel posts and beams with diagonal steel braces.
- Examine all accessible sides of the structure for damage. Pay particular attention to buildings with the irregular shapes noted in Figures 1 and 2 on the following pages. Damage to the structural system will typically show through nonstructural finishes. For example, cracks in stucco or plaster finishes are assumed to be equal in size to the cracks in the structural system hidden in the finish. Typical visible damages are as follows:
1) Wood studs with plywood sheathing - new gaps between plywood sheets 1/8" or larger, nail heads pulled out, or cracks 1/8" or larger in stucco over plywood are indicators of possible severe structural damage.
2) Brick masonry walls, concrete masonry walls or concrete walls - cracks 1/8" or larger indicate possible severe structural damage.
3) Concrete columns and beams - hairline cracks are generally not considered dangerous unless widespread. Exposed steel reinforcing, spalling of the concrete, or severe cracking indicate possible severe structural damage.
4) Steel posts, beams, diagonal braces and/or trusses - any buckling or bending (usually indicated by cracked or chipped paint) or any bolt failures or cracked welds indicate possible severe structural damage.
- Look for indicators of excessive horizontal movement in exterior walls which may result in a building being out-of-plumb (i.e., the top of the wall not in line with the bottom of the wall). Two typical indicators are broken glass in windows and jammed doors, but a building can move without breaking windows or jamming doors and still be out-of-plumb. Standing 20 to 30 feet from the corner of the building, look along all four edges of the building, checking for locations where the building is leaning. An offset from the top to the bottom of a wall, beyond what may have existed prior to the earthquake, of 1" or more may indicate severe structural damage.
- Examine exterior nonstructural elements, such as brick veneer, exterior cladding, overhangs, canopies, parapets, signs and ornamentation, for damage before evacuating or re-entering the building. Exterior cladding could be metal panels or precast concrete panels.
- Look for new fractures in the foundation or exposed lower walls of the building.
Figure 2 - Buildings with irregular shapes when viewed from above
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School Earthquake Preparedness Guide - State of
Arkansas Office of Emergency Services, 1993