Steel Frame Building Issues
In past earthquakes, fractures (cracks) occurred in steel frame buildings built before 1995 in two locations:
- In welds and steel elements in or near steel beam-to-column connections (see drawing and photo A below); and
- In column base plates (see photo B).
Such fractures are often small and hard to detect because they may be covered by fireproofing, interior walls and ceilings, and exterior facades. Slender or thin-walled steel braces can buckle prematurely in buildings built before 1982 (see photo C).
The reasons for damage to steel members are not fully known but may include workmanship, design, welding procedures, and material characteristics.
Some buildings with subtle structural damage also will suffer movement-related damage such as cracked finishes around columns and beams, cracked or out-of-plumb partitions or door frames, damaged ceilings, and broken glass. In cases of extreme damage, partial collapse may be possible
How to Identify
If your steel frame buildings have been exposed to strong ground shaking in the past and you have observed the damage described above, contact an appropriately experienced structural or civil engineer or architect to assess the need to investigate critical areas in the buildings. Owners of other steel buildings who are concerned about the potential for such damage are also encouraged to obtain qualified opinions.
Building investigations typically involve removing finishes and fireproofing at the beam column connections, visual observations, and testing, where appropriate. This work may disrupt occupants for a short time.
Repair and retrofit techniques and recommended guidelines are currently available from the Federal Emergency Management Agency (FEMA 350 to 353), the American Institute of Steel Construction (AISC 2005 Seismic Provisions and AISC 358) and the International Code Council (ICC) (see "Resource Organizations" below). Local government ordinances may also apply. Engineers should obtain and consider these latest guidelines, codes and standards when designing retrofits or repairs.
Structural Safety Information:
American Institute of Architects
Local chapters have referral lists of licensed architects; consult telephone directory listing for "American Institute of Architects."
Structural Engineers Association of California
1730 I Street, Suite 240,
Sacramento, CA 95814-3017
Telephone: (916) 447-1198
Local chapter organizations have referral list for licensed structural engineers as follows:
San Diego - http://www.seaosd.org/
Southern California - http://www.seaosc.org/
Northern California - http://www.seaonc.org/
Central California - http://www.seaocc.org/
Consulting Engineers and Land Surveyors of California
1303 J Street, Suite 450
Sacramento, CA 95814
Telephone: (916) 441-7991
A referral list for licensed engineers is available.
International Code Council
5360 Workman Mill Road
Whittier, CA 90601-2298
Telephone: (800) 284-4406