Information for Strong-Motion Station
Hayward - 4-story City Hall
CGS - CSMIP Station 58769
Earthquakes recorded by this station
(Station Photograph - click to enlarge)(Sensor Layout - click to see PDF File)
Latitude 37.6708 N
Longitude 122.0863 W
Elevation (m) 30
Site Geology Alluvium
Vs30 (m/sec) 338 (inferred)
Site Class D
Remarks/Notes Site information sources
No. of Stories above/below ground4/1
Plan ShapeRectangular
Base Dimensions120' x 210'
Typical Floor DimensionsVaries 120' x 210'
Design Date1996
Instrumentation12 accelerometers and 2 relative displacement sensors, on 5 levels in the building. 3 accelerometers at a reference free-field site.
Vertical Load Carrying SystemThe 1st floor slab is 10" concrete supported on concrete beams. The upper floors consist of a 3.25" lightweight concrete over 3" metal deck supported by steel beams and columns. Building is supported on 53 friction pendulum bearings which are installed on 7'10" tall concrete pedestals.
Lateral Force Resisting System4-story steel braced frames (chevron type) isolated with 53 friction pendulum system (FPS) bearings. Supplemental damping is provided by 15 viscous dampers between the Foundation and 1st Floor.
Foundation Type12" concrete mat foundation with 3' to 3.5' deep concrete grade beams in both directions.
RemarksDesigned according to 1994 UBC. Dynamic analysis was performed using ETABS and 3D-BASIS. The period of the fixed base building is about 0.4 sec. and that of the isolated building is about 3 sec.