URM Bldgs.

The

UnreinforcedMasonryBuilding

Hazard in Utah

 

Table of Contents

 

1.             Background and Introduction                                                    Carl + Others

 Hazard Potential of Utah’s Unreinforced Masonry Buildings.

 Include a quantitative assessment of the probable danger posed by URM’s in Utah.

 

 2.            Successful URM Retrofit Programs Review                                       Barry + Others

 Mitigation programs in surrounding states as well as historical information about unsuccessful attempts.

 

  3.            History of Existing Buildings Regulations in Utah                           Barry + Others

 Description of state regulations and local ordinances relative to existing building improvements.

 Implementation successes and problems.

 

 4.            Where Do/Can we go from Here                                                             Darlene + Others

 Possible programs and enforcement strategies.

 

 5.            Outcome Expectations                                                                               All

 What’s the expected result from a program to address URM’s?


 

White Paper Outline:

Resource links and supplemental information

 1.          Background and Introduction                                                                Carl + Others


2.         Successful URM Retrofit Programs Review                                   Barry + Others

     EERI “Best Practices” web page
  • California Seismic  Safety Commission web site
  • Oregon’s URM legislative efforts.
  • Washington’s programs
  • L.A. and S.F. programs and history 

3.         History of Existing Buildings Regulations in Utah                      Barry

 Building construction standards in the state of Utah are administered under the Uniform Building Standards Act (Utah Code Title 58, Chapter 56). This is a comprehensive statute creating a Uniform Building Code commission which advises the state Division of Occupational and Professional Licensing (DOPL) with respect to the divisions’ responsibilities in administering building and other codes. Additionally, the commission is charged with responsibility to recommend any code amendments to the director and to assist in the interpretation of the adopted code requirements.

 With the transformation of the International Conference of Building Officials (ICBO) into the International Code Council (ICC), Utah’s laws regarding adoption of specific building codes required changes. Legislation sponsored by Senator Parley G. Hellewell in 2002 (S.B. 55) took the necessary steps to update the appropriation portions of the Utah Uniform Building Standards Act. In addition to making the necessary technical changes, this bill gave DOPL, in collaboration with the Uniform Building Code commission, the authority to approve “certain other codes” without the need to adopt them statewide. It also managed to hand the political subdivisions the discretion to adopt a dangerous building code or rehabilitation code if the applicable code is one approved by the division.

 This resulted in the addition of the following construction standards being allowed for the regulation of existing buildings under the Utah Uniform Building Standards Act Rules (R156-56, Utah Administrative Code Issued July 17, 2003):

         1997 Uniform Code for the Abatement of Dangerous Buildings (UCADB)

        1997 Uniform Code for Building Conservation (UCBC)

        Guidelines for the Seismic Retrofit of Existing Buildings (GSREB)

        Guidelines for the Rehabilitation of Existing Buildings (GREB)

 Presently, Salt Lake City, OgdenCity and Provo have adopted the use of the 1997 UCBC.

 OgdenCity groundwork was instrumental in being the model for the states “parapet ordinance”.

 Two other significant steps in improving Utah’s existing buildings are adopted statewide through the Uniform Building Standards Acts Rules.

 1.    Amendment to section 1614.2 of the InternationalBuilding Code (R156-56-704 item 51) deletes and replaces it with the following:

1614.2 Change in Occupancy. When a change of occupancy results in a structure being reclassified to a higher Seismic Use Group, or when such change of occupancy results in a design occupant load increase of 100% or more, the structure shall conform to the seismic requirements for a new structure.

Exceptions:

1. This is not required if the design occupant load increase is less than 25 persons and the Seismic Use Group does not change.

2. Specific detailing provisions required for a new structure are not required to be met where it can be shown an equivalent level of performance and seismic safety contemplated for a new structure is obtained. Such analysis shall consider the regularity, over strength, redundancy and ductility of the structure within the context of the specific detailing provided. Alternatively, the building official may allow the structure to be upgraded in accordance with the latest edition of the “Guidelines for Seismic Rehabilitation of Existing Buildings” or another nationally recognized standard for retrofit of existing buildings.

2.      A new section 3402.5 was added as follows (R156-56-704 item 68):

3402.5 Parapets and other appendages. Building constructed prior to 1975 with parapet walls, cornices, spires, towers, tanks, signs, statuary and other appendages shall have such appendages evaluated by a licensed engineer to determine resistance to design loads specified in this code when said building is undergoing re-roofing, or alteration of or repair to said feature.

EXCEPTION: Group R-3 and U occupancies.

Original Plans and/or structural calculations may be utilized to demonstrate that the parapet or appendages are structurally adequate. When found to be deficient because of design or deteriorated condition, the engineer shall prepare specific recommendations to anchor, brace, reinforce or remove the deficient feature.

The maximum height of an unreinforced masonry parapet above the level of the diaphragm tension anchors or above the parapet braces shall not exceed one and one-half times the thickness of the parapet wall. The parapet height may be a maximum of two and one-half times its thickness in other than Seismic Design Categories D, E, or F. If the required parapet height exceeds this maximum height, a bracing system designed using the coefficients specified in Table 1621.2 shall support the top of the parapet. When positive diaphragm connections are absent, tension roof anchors shall be added. Approved alternative methods of equivalent strength will be considered when accompanied by engineer sealed drawings, details and calculations.


4.         Where Do/Can we go from Here                                                        Darlene + Others

    Survey existing URM building stock (quantify)
  • Assess the economic and human effects of the danger.
  • Prioritize the need for retrofitting URM buildings.
  • Recommendations for programs at state and local levels.

5.         Outcome Expectations                                                                           All

     Reduced liabilities
  • Better post-earthquake recovery
  • Protection of private and public assets and businesses.