3001 HEWITT AVE 2020-06-17 - Laserfiche WebLink

For buildings with substantial structural damage to lateral load resisting systems, IEBC 404.2.3 requires strengthening to resist a Reduced Seismic Force equal to 75%of IBC forces for new construction,therefore semi-permanent wall bracing will be designed to resist 75%of wall anchorage seismic force for new design. Per ASCE publication 37-14 Design Loads on Structures during Construction, Section 6.5 reduction of seismic design loads to account for short period of use is appropriate. Reduction to a value between 80%and 20%of full design loads is suggested depending on the expected exposure time. Phase 1 bracing will be designed for 50%of the Reduced Seismic Forces. Phase II bracing will be designed so that the combined Phase I and Phase II braces will resist 100%of the Reduced Seismic Force. The 2"d floor remains intact throughout most of the building and is expected to provide wall bracing. After Phase I bracing installation, the 2nd floor framing will be examined and wall to floor framing connections will be verified or strengthened if required. The bracing system consists of horizontal timber walers attached to the masonry walls with adhesive anchors. Vertical timbers are installed at each brace location and are bolted to each of the horizontal walers. The steel pipe braces are bolted to the vertical timbers and the brace bases anchored to concrete ecology blocks (2'x2'x4' each).