building codes. building codes: collapse prevention

Building Codes

Building codes: collapse prevention

The Uniform Building Code

• Building Seismic Safety Council (FEMA), 1996• Evolution of earthquake hazard maps• UBC-Level 4, area of highest risk

Areas of High Population/Seismic Risk

Seismic zones and Faults

Seismic zones and population

Damage Mapped by Damaged Buildings

Structural problems

• Earth material

• Soft story

• HOG

• Cripple wall

• House off foundation

• Chimneys

• Water heaters

• URM

Uniform Building Codes

• 1927- First UBC required, fire safety

• updated every 3 years• recognition of new

weaknesses in designs• recognition how earth

materials influence seismic waves

Soft Story Collapse

• Parking garage is a soft story

• Scenes like this were familiar near the epicenter

• Where have you seen this type of structure?

Uniform Building Code

• 1973- requires bracing of cripple walls

• 1991- stronger bracing for cripple walls

Cripple wall retrofit

Uniform Building Code

• 1935- Foundation bolting

Bolting Methods

Chimneys

• Built before 1970• Not properly

reinforced• Tear down chimney• 2007 building code

– Specific types of brick and mortar

– Extensive anchoring with specific requirements of attachment

• 1991-Bracing of water heaters

Uniform Building Code

• 1935- reinforcement of masonry foundations

• 1986- Unreinforced Masonry retrofit law

• 1993- how retrofitting is done

Uniform Building Code

Full Operational Operational Life safe Near Collapse

Safety-critical objective

Essential/hazardous objective

Basic objective

M6.5

M7.0

M8.0

M7.5

Building Code Objective