Preface

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This publication is prepared for information purposes only, it is not to be used as a construction document. This document is prepared for the owners of unreinforced masonry structures (URM), to gain a better understanding of the seismic improvement of their dwellings. Intended for use by contractors, repair specialists, and homeowners that possess construction skills above a typical "handyman" level.

The agencies and businesses involved in the design and preparation of this publication accept no responsibility for rehabilitation work or any action taken based on information found in this publication.

If the owner of a URM structure has a desire for greater assurance and reliability, a professional engineer and/or architect should be commissioned to design and detail specific corrective measures for their dwelling. Only through individual evaluation, analysis, design and inspection of a dwelling's construction can insure such corrective measures. Nevertheless, we are confident that URM homeowners can be successful in improving the seismic resistance of their dwellings through proper application of the information in this guide.

Unreinforced masonry dwellings were typically constructed prior to 1970, when seismic requirements were added to the Uniform Building Code. They were normally constructed with solid masonry-bearing walls without adequate reinforcement. As a result, URM structures lack the ability to move beyond the elastic limit required to absorb the seismic energy in an earthquake. Often the structures are quite brittle and can quickly fail when seismic activity is present. Thus, such URM structures should not be expected to perform adequately through a large seismic event.

The techniques shown in this document are intended to generally improve the seismic performance of a URM structure, but the implementation of these techniques cannot make a dwelling "Earthquake proof". There are a wide range of potential earthquakes. Moderate magnitude earthquakes occur periodically, and although minor damage is associated with these events, they can cause major destruction. High Magnitude ground shaking from a large quake may cause a strengthened or partially-strengthened structure to fail. It should be expected that damage will still occur; but generally, the more seismic measures taken to improve the structure, the greater the potential reduction in damage.