Unreinforced Masonry Buildings


Unreinforced masonry and existing reinforced concrete buildings are less ductile, meaning they are less able to accept horizontal and vertical  and therefore break or collapse easier.


Most unreinforced masonry buildings  roofs of light-frame construction supported by unreinforced brick or block walls. Structures that lack positive connections (metal connectors, straps, steel plates, hold-downs, etc.)  walls will not be able to resist intense 


 homeowners should add steel frames designed to resist the ground shaking in combination with additional anchorage 


Open-Front-Wall Buildings


In terms of plan and layout, open-front- wall buildings, where, for instance, cars  found to be vulnerable at the location where the exterior walls of the buildings are discontinued due to a parking spot (see photos).


 may include developing a lateral support system of steel-framed or reinforced-concrete shear walls.    ensuring lateral forces generated at


this level can be transferred to the new steel or concrete frame and then to the foundations.


Wood-Framed Buildings


Wood-framed buildings resist  walls may be a weak element of light- framed wood construction.


Wood-framed buildings’ ductile performance mainly relies on the connections between the different wood elements, nails, and steel


connectors, as well as their proper bracing. When proper bracing of the cripple wall studs and positive anchorage at the rim and foundation are provided, the wood building will 


Otherwise, the cripple wall element becomes a liability because during  cripple wall may collapse and the building will shift off its foundation.


Continued on Page 22  wscai.org 21


Before Seismic Improvement


 found to be vulnerable at the location where the exterior walls of the buildings are discontinued due to a parking spot.


Seismic ImprovementAfter


 system of steel-framed or reinforced-concrete shear walls. In this example, a steel  concrete shear wall that was added on the right-hand side.


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