El Segundo Municipal Code Ch. 18 Earthquake Hazard Reduction in Existing Buildings

A. Public Safety: The purpose of this chapter is to promote public safety and welfare by reducing the risk of death or injury that may result from the effects of earthquakes on unreinforced masonry bearing wall buildings constructed before 1934. Such buildings have been widely recognized for their sustaining of life hazardous damage as a result of partial or complete collapse during past moderate to strong earthquakes.

B. Seismic Resistance: The provisions of this chapter are minimum standards for structural seismic resistance established primarily to reduce the risk of life loss or injury and will not necessarily prevent loss of life or injury or prevent earthquake damage to an existing building which complies with these standards. This chapter shall not require existing electrical, plumbing, mechanical or fire safety systems to be altered unless they constitute a hazard to life or property.

C. Identification And Classification: This chapter provides systematic procedures and standards for identification and classification of unreinforced masonry bearing wall buildings based on their present use. Priorities, time periods and standards are also established under which these buildings are required to be structurally analyzed and anchored. Where the analysis determines deficiencies, this chapter requires the building to be strengthened or demolished. (Ord. 1152, 3-6-1990; amd. Ord. 1538, 12-6-2016)

A. Application Of Chapter: The provisions of this chapter shall apply to all buildings constructed or under construction prior to March 20, 1933, or for which a building permit was issued prior to March 20, 1933, which on the effective date hereof have "unreinforced masonry bearing walls" as defined herein.

B. Exception: This chapter shall not apply to detached one- or two-family dwellings and detached apartment houses containing fewer than five (5) dwelling units and used solely for residential purposes. (Ord. 1152, 3-6-1990; amd. Ord. 1538, 12-6-2016)

For the purposes of this chapter, the applicable definitions in sections 2302 and 2312 of the building code of the city, and the following shall apply:

BUILDING CODE, CITY OF LOS ANGELES: Shall refer to the 1985 Los Angeles city building code.

DIVISION OF BUILDING SAFETY: Shall refer to the building and safety division of the community development department of the city of El Segundo.

ESSENTIAL BUILDING: Any building housing a hospital or other medical facility having surgery or emergency treatment areas, and those structures which are necessary for emergency postearthquake operations.

HIGH RISK BUILDINGS: Any building not classified an essential building having an occupant load of one hundred (100) occupants or more.

Exception: A high risk building shall not include the following:

A. Any building having exterior walls braced with masonry cross walls or wood frame cross walls spaced less than forty feet (40') apart in each story. Cross walls shall be full story height with a minimum length of one and one-half (11/2) times the story height.

B. Any building used for its intended purpose, as determined by the division, for less than twenty (20) hours per week.

LOW RISK BUILDING: Any building not classified an essential building having an occupant load of less than twenty (20) occupants.

MEDIUM RISK BUILDING: Any building not classified as a high risk building or an essential building having an occupant load of twenty (20) occupants or more.

UNREINFORCED MASONRY BEARING WALL: A masonry wall having all of the following characteristics:

A. Provides the vertical support for a floor or roof.

B. The total superimposed load is over one hundred (100) pounds per linear foot.

C. The area of reinforcing steel is less than fifty percent (50%) of that required by section 2407 of the building code of the city. (Ord. 1152, 3-6-1990; amd. Ord. 1538, 12-6-2016; Ord. 1639, 9-20-2022)

A. Ratings Established: The rating classifications as exhibited in section 13-18-10, table 88-A of this chapter, are hereby established and each building within the scope of this chapter shall be placed in one such rating classification by the division of building safety. The total occupant load of the entire building shall be used to determine the rating classification.

B. Exceptions: For the purpose of this chapter, portions of buildings constructed to act independently when resisting seismic forces may be placed in separate rating classifications. (Ord. 1152, 3-6-1990; amd. Ord. 1538, 12-6-2016)

A. Structural Analysis: The owner of each building within the scope of this chapter shall cause a structural analysis to be made of the building by a civil or structural engineer or architect licensed by the state, and if the building does not meet the minimum earthquake standards specified in this chapter, the owner shall cause it to be structurally altered to conform to such standards or cause the building to be demolished.

B. Time Limits: The owner of a building within the scope of this chapter shall comply with the requirements set forth above by submitting to the community development department, building safety division, for review within the stated time limits:

1. Within two hundred seventy (270) days after the service of the order, a structural analysis shall be made by a civil or structural engineer or architect licensed by the state. Such analysis, which is subject to approval by the division of building safety, shall demonstrate that the building meets the minimum requirements of this chapter; or

2. Within two hundred seventy (270) days after the service of the order, the structural analysis and plans for the proposed structural alterations of the building necessary to comply to the minimum requirements of this chapter; or

3. Within one hundred twenty (120) days after service of the order, plans for the installation of wall anchors in accordance with the requirements specified in subsection 13-18-7C of this chapter; or

4. Within two hundred seventy (270) days after the service of the order, plans for the demolition of the building.

C. Obtain Building Permit; Complete Work: After plans are submitted and approved by the division of building safety, the owner shall obtain a building permit, commence and complete the required construction or demolition within the time limits set forth in section 13-18-10, table 88-B of this chapter. These time limits shall begin to run from the date the order is served in accordance with subsections 13-18-6A and B of this chapter.

D. Extended Time Limits: Owners electing to comply with subsection B3 of this section are also required to comply with subsection B2 or B4 of this section; provided, however, that the two hundred seventy (270) day period provided for in such subsections B2 and B4 of this section and the time limits for obtaining a building permit, commencing construction and completing construction for complete structural alterations or building demolition set forth in section 13-18-10, table 88-B of this chapter, shall be extended in accordance with in section 13-18-10, table 88-C of this chapter. Each such extended time limit, except the time limit for commencing construction, shall begin to run from the date the order is served in accordance with subsection 13-18-6B of this chapter. The time limit for commencing construction shall commence to run from the date the building permit is issued. (Ord. 1152, 3-6-1990; amd. Ord. 1538, 12-6-2016; Ord. 1639, 9-20-2022)

A. Service Of Order: The division shall issue an order, as provided in subsection B of this section, to the owner of each building within the scope of this chapter in accordance with the minimal time periods for service of such orders set forth in section 13-18-10, table 88-C of this chapter. The minimum time period for the service of such orders shall be measured from the effective date of this chapter. The division shall, upon receipt of a written request from the owner, order a building to comply with this chapter prior to the normal service date for such building set forth in this section.

B. Contents Of Order: The order shall be in writing and shall be served either personally or by certified or registered mail upon the owner as shown on the last equalized assessment, and upon the person, if any, in apparent charge or control of the building. The order shall specify that the building has been determined by the division to be within the scope of this chapter and, therefore, is required to meet the minimum seismic standards of this chapter. The order shall specify the rating classification of the building and shall be accompanied by a copy of section 13-18-5 of this chapter, which sets forth the owner's alternatives and time limits for compliance.

C. Appeal Form Order:

1. The owner or person in charge or control of the building may appeal the division's initial determination that the building is within the scope of this chapter to the board of examiners and appeals. Such appeal shall be filed with the building official within sixty (60) days from the service date of the order described in subsection B of this section. Any such appeal shall be decided by the board of examiners and appeals no later than sixty (60) days after the date that the appeal is filed. Such appeal shall be made in writing upon appropriate forms provided therefor by the division, and the grounds thereof shall be stated clearly and concisely.

2. Appeals or requests for slight modifications from any other determinations, orders or actions by the division pursuant to this chapter shall be made in accordance with procedures established in chapter 1 of this title.

D. Recordation:

1. At the time that the division serves the aforementioned order, the division shall file with the office of the county recorder a certificate stating that the subject building is within the scope of this chapter. The certificate shall also state that the owner thereof has been ordered to structurally analyze the building and to structurally alter or demolish it where compliance with this chapter is not exhibited.

2. If the building is either demolished, found not to be within the scope of this chapter, or is structurally capable of resisting minimum seismic forces required by this chapter as a result of structural alterations or an analysis, the division shall file with the office of the county recorder a certificate terminating the status of the subject building as being classified within the scope of this chapter.

E. Enforcement: If the owner or other person in charge or control of the subject building fails to comply with any order issued by the division pursuant to this chapter within any of the time limits set forth in section 13-18-5 of this chapter, the division shall order that the entire building be vacated and that the building remain vacated until such order has been complied with. If compliance with such order has not been accomplished within ninety (90) days after the date the building has been ordered vacated or such additional time as may have been granted by the board of examiners and appeals, the building official may order its demolition in accordance with the provisions of section 13-18-1 of this chapter. (Ord. 1152, 3-6-1990; amd. Ord. 1538, 12-6-2016)

A. General:

1. Every structure within the scope of this chapter shall be analyzed and constructed to resist minimum total lateral seismic forces assumed to act nonconcurrently in the direction of each of the main axes of the structure in accordance with the following equation:

v = IKCSW - - - (88-1)

2. The value of IKCSW need not exceed the values set forth in section 13-18-10, table 88-D of this chapter, based on the applicable rating classification of the building.

B. Lateral Forces On Elements Of Structures:

1. Equation:

a. Parts or portions of structures shall be analyzed and designed for lateral loads in accordance with subsection A of this section but not less than the value from the following equation:

Fp = ICp SWp - - - (88.2)

b. For the provisions of this subsection, the product of IS need not exceed the values as set forth in section 13-18-10, table 88-E of this chapter.

2. Exception: Unreinforced masonry walls in buildings not having a rating classification of I may be analyzed in accordance with section 13-18-8 of this chapter.

The value of Cp need not exceed the values set forth in section 13-18-10 , table 88-F of this chapter.

C. Anchorage And Interconnection: Anchorage and interconnection of all parts, portions and elements of the structure shall be analyzed and designed for lateral forces in accordance with section 13-18-10, table 88-F of this chapter, and the equation Fp = Cp SWp as modified by section 13-18-10 , table 88-E of this chapter. Minimum anchorage of masonry walls to each floor or roof shall resist a minimum force of two hundred (200) pounds per linear foot acting normal to the wall at the level of the floor or roof.

D. Level Of Required Repair: Alterations and repairs required to meet the provisions of this chapter shall comply with all other applicable requirements of this code unless specifically provided for in this chapter.

E. Required Analysis:

1. General: Except as modified herein, the analysis and design relating to the structural alteration of existing structures within the scope of this chapter shall be in accordance with the analysis specified in chapter 23 of the building code of the city.

2. Continuous Stress Path: A complete, continuous stress path from every part or portion of the structure to the ground shall be provided for the required horizontal forces.

3. Positive Connections: All parts, portions or elements of the structure shall be interconnected by positive means.

F. Analysis Procedure:

1. General: Stresses in materials and existing construction utilized to transfer seismic forces from the ground to parts or portions of the structure shall conform to those permitted by the code and those materials and types of construction specified in section 13-18-8 of this chapter.

2. Connections: Materials and connectors used for interconnection of parts and portions of the structure shall conform to the code. Nails may be used as part of an approved connector.

3. Unreinforced Masonry Walls:

a. Except as modified herein, unreinforced masonry walls shall be analyzed as specified in sections 2406 and 2409 to withstand all vertical loads as specified in chapter 23 of the building code of the city in addition to the seismic forces required by this chapter.

b. No allowable tension stress will be permitted in unreinforced masonry walls. Walls not capable of resisting the required design forces specified in this division shall be strengthened or shall be removed and replaced.

4. Exceptions:

a. Unreinforced masonry walls in buildings not classified as a rating classification I pursuant to section 13-18-10, table 88-A of this chapter, may be analyzed in accordance with section 13-18-8 of this chapter.

b. Unreinforced masonry walls which carry no design loads other than their own weight may be considered as veneer if they are adequately anchored to new supporting elements.

G. Combination Of Vertical And Seismic Forces:

1. New Materials: All new materials introduced into the structure to meet the requirements of this section which are subjected to combined vertical and horizontal forces shall comply with the building code of the city.

2. Existing Materials: When stresses in existing lateral force- resisting elements are due to a combination of dead loads plus seismic loads, the allowable working stress specified in the code may be increased one hundred percent (100%). However, no increase will be permitted in the stresses allowed in section 13-18-8 of this chapter and the stresses in members due only to seismic and dead loads shall not exceed the values permitted by section 2303(d) of the building code of the city.

3. Allowable Reduction Of Bending Stress By Vertical Load: In calculating tensile fiber stress due to seismic forces required by this chapter, the maximum tensile fiber stress may be reduced by the full direct stress due to vertical dead loads. (Ord. 1152, 3-6-1990; amd. Ord. 1538, 12-6-2016)

A. General: All materials permitted by this code, including their appropriate allowable stresses and those existing configurations of materials specified herein, may be utilized to meet the requirements of this chapter.

B. Existing Materials:

1. Unreinforced Masonry Walls:

a. Unreinforced masonry walls analyzed in accordance with this section may provide vertical support for roof and floor construction and resistance to lateral loads. The bonding of such walls shall be as specified in section 2403(a) of the building code of the city of El Segundo.

b. Tension stresses due to seismic forces normal to the wall may be neglected if the wall does not exceed the height or length to thickness ratio and the in-plane shear stresses due to seismic loads as set forth in section 13-18-10, table 88-G of this chapter.

c. If the wall height-thickness ratio exceeds the specified limits, the wall may be supported by vertical bracing members designed in accordance with chapter 23 of the building code of the city. The deflection of such bracing member at design loads shall not exceed one-tenth (1/10) of the wall thickness.

Exception: The wall may be supported by flexible vertical bracing members designed in accordance with section 13-18-7 of this chapter if the deflection at design loads is not less than one-fourth (1/4) nor more than one-third (1/3) of the wall thickness.

d. All vertical bracing members shall be attached to floor and roof construction for their design loads independently of required wall anchors. Horizontal spacing of vertical bracing members shall not exceed one-half (1/2) the unsupported height of the wall nor ten feet (10').

e. The wall height may be measured vertically to bracing elements other than a floor or roof. Spacing of the bracing elements and wall anchors shall not exceed six feet (6'). Bracing elements shall be detailed to minimize the horizontal displacement of the wall by components of vertical displacements of the floor or roof.

2. Existing Roof, Floors, Walls, Footings And Wood Framing: Existing materials, including wood shear walls utilized in the described configuration, may be used as part of the lateral load resisting system; provided, that the stresses in these materials do not exceed the values shown in section 13-18-10, table 88-H of this chapter.

C. Strengthening Of Existing Materials: New materials, including wood shear walls, may be utilized to strengthen portions of the existing seismic resisting system in the described configurations; provided, that the stresses do not exceed the values shown in section 13-18-10, table 88-I of this chapter.

D. Alternate Materials: Alternate materials, designs and methods of construction may be approved by the division in accordance with the provisions of section 105 of the uniform building code.

E. Minimum Acceptable Quality Of Existing Unreinforced Masonry Walls:

1. General Provisions: All unreinforced masonry walls utilized to carry vertical loads and seismic forces parallel and perpendicular to the wall plane shall be tested as specified in this subsection. All masonry quality shall equal or exceed the minimum standards established herein or shall be removed and replaced by new materials. Alternate methods of testing may be approved by the division. The quality of mortar in all masonry walls shall be determined by performing in-place shear tests or by testing eight inch (8") diameter cores. Nothing shall prevent pointing with mortar of all the masonry wall joints before the tests are first made. Prior to any pointing, the mortar joints must be raked and cleaned to remove loose and deteriorated mortar. Mortar for pointing shall be type S or N except masonry cements shall not be used. All preparation and mortar pointing shall be done under the continuous inspection of a registered special inspector. At the conclusion of the inspection, the inspector shall submit a written report to the licensed engineer or architect responsible for the seismic analysis of the building setting forth the result of the work inspected. Such report shall be submitted to the division for approval as part of the structural analysis. All testing shall be performed in accordance with the requirements specified in this subsection by a testing agency approved by the division. An accurate record of all such tests and their location in the building shall be recorded and these results shall be submitted to the division for approval as part of the structural analysis.

2. Number And Location Of Tests: The minimum number of tests shall be two (2) per wall or line of wall elements resisting a common force, or one per one thousand five hundred (1,500) square feet of wall surface, with a minimum of eight (8) tests in any case. The exact test or core location shall be determined at the building site by the licensed engineer or architect responsible for the seismic analysis of the subject building.

3. In-Place Shear Tests: The bed joints of the outer wythe of the masonry shall be tested in shear by laterally displacing a single brick relative to the adjacent bricks in that wythe. The opposite head joint of the brick to be tested shall be removed and cleaned prior to testing. The minimum quality mortar in eighty percent (80%) of the shear tests shall not be less than the total of thirty (30) psi plus the axial stress in the wall at the point of the test. The shear stress shall be based on the gross area of both bed joints and shall be that at which movement of the brick is first observed.

4. Core Tests: A minimum number of mortar test specimens equal to the number of required cores shall be prepared from the cores and tested as specified herein. The mortar joint of the outer wythe of the masonry core shall be tested in shear by placing the circular core section in a compression testing machine with the mortar bed joint rotated fifteen degrees (15°) from the axis of the applied load. The mortar joint tested in shear shall have an average ultimate stress of twenty (20) psi based on the gross area. The average shall be obtained from the total number of cores made. If test specimens cannot be made from cores taken, then the shear value shall be reported as zero.

F. Testing Of Shear Bolts:

1. One-fourth (1/4) of all new shear bolts and dowels embedded in unreinforced masonry walls shall be tested by a registered special inspector using a torque calibrated wrench to the following minimum torques:

2. No bolts exceeding three-fourths inch (3/4") shall be used. All nuts shall be installed over malleable iron or plate washers when bearing on wood and heavy cut washers when bearing on steel.

G. Determination Of Allowable Stresses For Design Methods Based On Test Results:

1. Design Shear Values:

a. Design seismic in-plane shear stresses shall be substantiated by tests performed as specified in subsections E3 and E4 of this section.

b. Design stresses shall be related to test results obtained in accordance with section 13-18-10, table 88-J of this chapter. Intermediate values between three (3) and ten (10) psi may be interpolated.

2. Design Compression And Tension Values: Compression stresses for unreinforced masonry having a minimum design shear value of three (3) psi shall not exceed one hundred (100) psi. Design tension values for unreinforced masonry shall not be permitted.

H. Rod Anchors; Testing: Five percent (5%) of the existing rod anchors utilized as all or part of the required wall anchors shall be tested in pullout by an approved testing laboratory. The minimum number tested shall be four (4) per floor, with two (2) tests at walls with joists framing into the wall and two (2) tests at walls with joists parallel to the wall. The test apparatus shall be supported on the masonry wall at a minimum distance of the wall thickness from the anchor tested. The rod anchor shall be given a preload of three hundred (300) pounds prior to establishing a datum for recording elongation. The tension test load reported shall be recorded at one-eighth inch (1/8") relative movement of the anchor and the adjacent masonry surface. Results of all tests shall be reported. The report shall include the test results as related to the wall thickness and joist orientation. The allowable resistance value of the existing anchors shall be forty percent (40%) of the average of those tested anchors having the same wall thickness and joist orientation.

I. Wall Anchorage; Testing: Qualification tests for devices used for wall anchorage shall be tested with the entire tension load carried on the enlarged head at the exterior face of the wall. Bond on the part of the device between the enlarged head and the interior wall face shall be eliminated for the qualification tests. The resistance value assigned the device shall be twenty percent (20%) of the average of the ultimate loads. (Ord. 1152, 3-6-1990; amd. Ord. 1538, 12-6-2016)

A. General: In addition to the seismic analysis required elsewhere in this chapter, the licensed engineer or architect responsible for the seismic analysis of the building shall determine and record the information required by this section on the approved plans.

B. Construction Details: The following requirements with appropriate construction details shall be made part of the approved plans:

1. All unreinforced masonry walls shall be anchored at the roof level by tension bolts through the wall as specified in section 13-18-10, table 88-I of this chapter, or by approved equivalent at a maximum anchor spacing of six feet (6'). Anchors installed in accordance with section 91.810(q) of the city of Los Angeles building code shall be accepted as conforming to this requirement.

All unreinforced masonry walls shall be anchored at all floors with tension bolts through the wall or by existing rod anchors at a maximum anchor spacing of six feet (6'). All existing rod anchors shall be secured to the joists to develop the required forces. The division may require testing to verify the adequacy of the embedded ends of existing rod anchors. Tests when required shall conform to subsection 13-18-8H of this chapter.

When access to the exterior face of the masonry wall is prevented by proximity of an existing building, wall anchors conforming to section 13-18-10, table 88-I, items 5 and 6 of this chapter, may be used.

Alternative devices to be used in lieu of tension bolts for masonry wall anchorage shall be tested as specified in subsection 13-18-8I of this chapter.

2. Diaphragm chord stresses of horizontal diaphragms shall be developed in existing materials or by addition of new materials.

3. Where trusses and beams other than rafters or joists are supported on masonry, ledges or columns shall be installed to support vertical loads of the roof or floor members.

4. Parapets and exterior wall appendages not capable of resisting the forces specified in this chapter shall be removed, stabilized or braced to ensure that the parapets and appendages remain in their original position.

5. All deteriorated mortar joints in unreinforced masonry walls shall be pointed with type S or N mortar. Prior to any pointing, the wall surface must be raked and cleaned to remove loose and deteriorated mortar. All preparation and pointing shall be done under the continuous inspection of a registered special inspector certified to inspect masonry or concrete. At the conclusion of the project, the inspector shall submit a written report to the division setting forth the portion of work inspected.

6. Repair details of any cracked or damaged unreinforced masonry wall required to resist forces specified in this chapter.

C. Existing Construction: The following existing construction information shall be made part of the approved plans:

1. The type and dimensions of existing walls and the size and spacing of floor and roof members.

2. The extent and type of existing wall anchorage to floors and roof.

3. The extent and type of parapet corrections which were performed in accordance with the building code of the city.

4. Accurately dimensioned floor plans and masonry wall elevations showing dimensioned openings, piers, wall thickness and heights.

5. The location of cracks or damaged portions of unreinforced masonry walls requiring repairs.

6. The type of interior wall surfaces and if reinstalling or anchoring of ceiling plaster is necessary.

7. The general condition of the mortar joints and if the joints need pointing. (Ord. 1152, 3-6-1990; amd. Ord. 1538, 12-6-2016)

TABLE 88-A RATING CLASSIFICATIONS

TABLE 88-B TIME LIMITS FOR COMPLIANCE

Note:

1. Measured from date of building permit issuance.

TABLE 88-C SERVICE PRIORITIES AND EXTENDED TIME PROVISIONS

TABLE 88-D HORIZONTAL FORCE FACTORS BASED ON RATING CLASSIFICATION

TABLE 88-E HORIZONTAL FORCE FACTORS "IS" FOR PARTS OR PORTIONS OF STRUCTURES

TABLE 88-F HORIZONTAL FORCE FACTOR "C" FOR PARTS OR PORTIONS OF BUILDINGS OR OTHER STRUCTURES

Notes:

See subsection 13-18-7B of this chapter for use of Cp.

When located in the upper portion of any building with a ratio of 5 to 1 or greater, the value shall be increased by 50 percent.

For flexible and flexibly mounted equipment and machinery, the appropriate values for C shall be determined with consideration given to both the dynamic properties of the equipment and machinery and to the building or structure in which it is placed.

The Wp for storage racks shall be the weight of the racks plus contents. The value of C for racks over 2 storage support levels in height shall be 0.16 for the levels below the top 2 levels.

The design of the equipment and machinery and their anchorage is an integral part of the design and specification of such equipment and machinery. The structure to which the equipment or machinery is mounted shall be capable of resisting the anchorage forces (see also section 2312(g) of the building code of the city of El Segundo).

Floor and roofs acting as diaphragms shall be designed for a minimum force resulting from a Cp of 112 applied to Wp unless a greater force results from the distribution of lateral forces in accordance with section 2312(e) of the building code of the city of El Segundo.

TABLE 88-G ALLOWABLE VALUE OF HEIGHT-THICKNESS RATIO OP UNREINFORCED MASONRY WALLS WITH MINIMUM QUALITY MORTAR

Notes:

Minimum quality mortar shall be determined by laboratory testing in accordance with subsection 13-18-8E of this chapter.

This table is not applicable to buildings of rating classification I. Walls of buildings within rating classification I shall be analyzed in accordance with subsection 13-18-7E of this chapter.

TABLE 88-H VALUES FOR EXISTING MATERIALS

Notes:

Material must be sound and in good condition.

The wood lath and plaster must be reattached to existing joists or rafters in a manner approved by the division.

Stresses given may be increased for combinations of loads as specified in subsection 13-18-7G2 of this chapter.

TABLE 88-I ALLOWABLE VALUES OF NEW MATERIALS USED IN CONJUNCTION WITH EXISTING CONSTRUCTION

Notes:

Bolts and dowels to be tested as specified in subsection 13-18-8F of this chapter.

Bolts and dowels to be 1/2 inch minimum in diameter.

Drilling for bolts and dowels shall be done with an electric rotary drill. Impact tools shall not be used for drilling holes or tightening anchor and shear bolt nuts.

TABLE 88-J ALLOWABLE SHEAR STRESS FOR TESTED UNREINFORCED MASONRY WALLS

Note:

1. Allowable shear stress may be increased by addition of 10 percent of axial stress due to the weight of the wall directly above.

(Ord. 1152, 3-6-1990; amd. Ord. 1538, 12-6-2016)

§ 13-18-V100: Voluntary Earthquake Hazard Reduction In Existing Reinforced Concrete And Reinforced Masonry Wall Buildings With Flexible Diaphragms.

§ 13-18-V101: Purpose.

The purpose of this chapter is to promote public safety and welfare by reducing the risk of death or injury that may result from the effects of earthquakes on reinforced concrete and masonry wall buildings with flexible diaphragms designed under the building codes in effect before January 1, 1995. These buildings are potentially hazardous and prone to significant damage, including possible collapse, in a moderate to major earthquake. These structures typically shelter large numbers of persons and property for retail, food markets, food distribution centers, warehousing, aerospace, industrial/manufacturing and general business and office use. Their continued use after an earthquake is also essential to the local economy and its post- earthquake recovery.

The provisions of this chapter are minimum standards for structural seismic resistance established primarily to reduce the risk of loss of life or injury on both subject and adjacent properties and will not necessarily prevent all earthquake damage to an existing building which complies with these standards. This chapter cannot require existing electrical, plumbing, mechanical or fire safety systems to be altered unless they constitute a hazard to life or property.

This chapter provides voluntary retrofit standards for deficient wall anchorage systems on structures that are not subject to the mandatory provisions of this chapter. When fully followed, these standards will strengthen the portion of the structure that is most vulnerable to earthquake damage.

§ 13-18-V102: Scope.

The voluntary provisions of this chapter apply to existing buildings of the following types:

1. Cast-in-place reinforced concrete or masonry wall buildings with flexible diaphragms designed under building codes in effect before January 1, 1995.

2. Tilt-up concrete wall buildings with flexible diaphragms designed under the building codes in effect before January 1, 1995, but after January 1, 1976.

All existing reinforced masonry or concrete buildings with flexible diaphragms, including tilt-up concrete wall buildings, designed under the building code in effect on or after January 1, 1995, must be designed in conformance with chapter 16 of the CBC.

§ 13-18-V103: Definitions.

For the purposes of this chapter, the applicable definitions in chapter 2, chapter 16, chapter 19 and chapter 23 of this code; chapter 1, chapter 3, chapter 4, chapter 5, chapter 6 and chapter 11 of ASCE 7, and the following apply:

Anchorage System is the system of all structural elements and connections, which support the concrete or masonry wall in the lateral direction, including diaphragms and subdiaphragms, wall anchorage and continuity or cross tie connectors in subdiaphragms and main diaphragms.

Commenced Construction is construction pursuant to a valid building permit that has progressed to the point that one of the called inspections as required by the department has been made and the work for which the inspection has been called has been judged by the department to be substantial and has been approved by the department.

Existing Building is an erected building for which a legal building permit and a certificate of occupancy have been issued.

Flexible Diaphragm is any diaphragm constructed of wood structural panel, diagonal or straight wood sheathing, metal decking without a structural concrete topping, or horizontal rod bracing.

Historical Building is any building designated or currently in the process of being designated as a historical building by an appropriate federal, state or city jurisdiction.

Reinforced Concrete Wall is a concrete wall that has 50 percent or more of the reinforcing steel required for reinforced concrete in chapter 19.

Reinforced Masonry Wall is a masonry wall that has 50 percent or more of the reinforcing steel required by chapter 21.

Retrofit is strengthening or structurally improving the lateral force resisting system of an existing building by alteration of existing or addition of new structural elements.

Tilt-Up Concrete Wall is a form of precast concrete panel construction either cast in the horizontal position at the site and after curing, lifted and moved into place in a vertical position, or cast off-site in a fabricator's shop.

§ 13-18-V104: Analysis And Design.

V104.1. Wall Panel Anchorage. Concrete and masonry walls must be anchored to all floors and roofs which provide lateral support for the wall. The anchorage must provide a positive direct connection between the wall and floor or roof construction capable of resisting a horizontal force equal to 30 percent of the tributary wall weight for all buildings, and 45 percent of the tributary wall weight for essential buildings, or a minimum force of 250 pounds per linear foot of wall, whichever is greater. The required anchorage must be based on the tributary wall panel assuming simple supports at floors and roof.

Exception: An alternate design may be approved by the building official when justified by well-established principles of mechanics.

V104.2. Special Requirements For Wall Anchors And Continuity Ties. The steel elements of the wall anchorage systems and continuity ties must be designed by the allowable stress design method using a load factor of 1.7. The 1/3 stress increase permitted by chapter 16 cannot be permitted for materials using allowable stress design methods. The strength design specified in chapter 19 using a load factor of 2.0 in lieu of 1.4 for earthquake loading, must be used for the design of embedment in concrete. Wall anchors must be provided to resist out-of-plane forces, independent of existing shear anchors.

Exception: Existing cast-in-place shear anchors may be used as wall anchors if the tie element can be readily attached to the anchors and if the engineer or architect can establish tension values for the existing anchors through the use of approved as-built plans or testing, and through analysis showing that the bolts are capable of resisting the total shear load while being acted upon by the maximum tension force due to seismic loading. Criteria for analysis and testing must be determined by the building official.

Expansion anchors are not allowed without special approval of the building official. Attaching the edge of plywood sheathing to steel ledgers is not considered as complying with the positive anchoring requirements of the code; and attaching the edge of steel decks to steel ledgers is not considered as providing the positive anchorage of this code unless testing and analysis are performed, which establish shear values for the attachment perpendicular to the edge of the deck.

V104.3. Development Of Anchor Loads Into The Diaphragm. Development of anchor loads into roof and floor diaphragms must comply with chapter 12 of ASCE 7.

Exception: If continuously tied girders are present, then the maximum spacing of the continuity ties is the greater of the girder spacing or 24 feet (7315 mm). In wood diaphragms, anchorage cannot be accomplished by use of toe nails or nails subject to withdrawal, nor must wood ledgers, top plates or framing be used in cross-grain bending or cross- grain tension. The continuous ties required by chapter 12 of ASCE 7 must be in addition to the diaphragm sheathing. Lengths of development of anchor loads in wood diaphragms must be based on existing field nailing of the sheathing unless existing edge nailing is positively identified on the original construction plans or at the site. At reentrant corners, continuity collectors may be required for existing return walls not designed as shear walls, to develop into the diaphragm a force equal to the lesser of the rocking or shear capacity of the return wall, or the tributary shear but not exceeding the capacity of the diaphragm. Shear anchors for the return wall must be commensurate with the collector force. If a truss or beam other than rafters or purlins is supported by the return wall or by a column integral with the return wall, an independent secondary column is required to support the roof or floor members whenever rocking or shear capacity of the return wall is governing.

V104.4. Anchorage At Pilasters. Anchorage of pilasters must be designed for the tributary wall anchoring load per section V104.1 of this code, considering the wall as a two-way slab. The edge of the two-way slab must be considered "fixed" when there is continuity at pilasters, and considered "pinned" at roof or floor levels. The pilasters or the walls immediately adjacent to the pilasters must be anchored directly to the roof framing such that the existing vertical anchor bolts at the top of the pilasters are by-passed without causing tension or shear failure at the top of the pilasters.

Exception: If existing vertical anchor bolts at the top of the pilasters are used for the anchorage, then additional exterior confinement must be provided. The minimum anchorage at a floor or roof between the pilasters must be that specified in section V104.1 of this code.

V104.5. Symmetry. Symmetry of connectors in the anchorage system is required. Eccentricity may be allowed when it can be shown that all components of forces are positively resisted and justified by calculations or tests.

V104.6. Minimum Roof Member Size. Wood members used to develop anchorage forces to the diaphragm must be of minimum nominal width for new construction and replacement. All such members must be designed for gravity and earthquake forces as part of the wall anchorage system. For existing structural members, the allowable stresses must be without the 1/3 stress increase per section V104.2.

V104.7. Combination Of Anchor Types. To repair and retrofit existing buildings, a combination of different anchor types of different behavior or stiffness is prohibited. The capacity of the new and existing connectors cannot be added.

V104.8. Prohibited Anchors. Usage of connectors that were bent or stretched from the intended use is prohibited.

V104.9. Crack And Damage Repairs, Evaluation Of Existing Structural Alterations. The engineer or architect must report any observed structural conditions and structural damage that have imminent life safety effects on the buildings and recommend repairs. This includes alterations such as openings cut in existing wall panels without a building permit. Evaluations and repairs must be reviewed and approved by the building official.

V104.10. Miscellaneous. Existing mezzanines relying on the concrete or masonry walls for vertical or lateral support must be anchored to the walls for the tributary mezzanine load. Walls depending on the mezzanine for lateral support must be anchored per sections V104.1, V104.2 and V104.3 of this code.

Exception: Existing mezzanines that have independent lateral and vertical support need not be anchored to the concrete or masonry walls. Existing interior masonry or concrete walls not designed as shear walls, which extend to the floor above or to the roof diaphragm must also be anchored for out-of- plane forces per section V104.1, V104.2 and V104.3 of this code. In the in-plane direction, the walls may be isolated or must be developed into the diaphragm for a lateral force equal to the lesser of the rocking or shear capacity of the wall, or the tributary shear but not exceeding the diaphragm capacity.

V104.11. Historical Buildings. Qualified historical buildings must be permitted to use alternate building standards or deviations from this chapter in order to preserve their original or restored architectural elements and features.

§ 13-18-V105: Materials Of Construction.

All materials permitted by this code.

§ 13-18-V106: Information Required On Plans.

V106.1. General. In addition to the seismic analysis required elsewhere in this chapter, the licensed engineer or architect responsible for the seismic analysis of the building must record the information required by this section on the approved plans.

V106.2. Information Required. The plans must accurately reflect the results of the engineering investigation and design and show all pertinent dimensions and sizes for plan review and construction. The following must be provided:

1. Floor plans and roof plans must show the existing framing construction, diaphragm construction, proposed wall anchors, cross-ties and collectors. Existing nailing, anchors, ties and collectors must also be shown on the plans if these are part of the design, and these structural elements need to be verified in the field.

2. At elevations where there is alterations or damage, the details must show the roof and floor heights, dimensions of openings, location and extent of existing damage, and proposed repair.

3. Typical concrete or masonry wall sections with wall thickness, height, and location of anchors must be provided.

4. Details must include the existing and new anchors and the method of development of anchor forces into the diaphragm framing; existing and new cross-ties, existing and new or improved support of the roof and floor girders at pilasters or walls.

V106.3. Engineer's Or Architect's Statement. The responsible engineer or architect must state on the approved plans, the following:

1. "I am responsible for this building's seismic strengthening design of the tilt-up concrete wall anchorage system in compliance with the minimum seismic resistance standards of chapter V1 of the California Building Code, as adopted by the El Segundo Municipal Code." or when applicable:

2. "The Registered Deputy Inspector, required as a condition of the use of structural design stresses requiring continuous inspection, will be responsible to me, the California Licensed Engineer or Architect, as required by Section 1704 of the California Building Code, as adopted by the El Segundo Municipal Code."

§ 13-18-V107: Required Building Maintenance.

Every building within the scope of this chapter which has been analyzed to demonstrate compliance or structurally altered to comply with the minimum earthquake standards in this chapter must be maintained in conformity with the requirements of this chapter in effect at the time of such analysis or structural alteration.

TABLE NO. V1-A RATING CLASSIFICATIONS

(Ord. 1538, 12-6-2016)

§ 13-18-V200: VOLUNTARY PRESCRIPTIVE PROVISIONS FOR SEISMIC STRENGTHENING OF CRIPPLE WALLS AND SILL PLATE ANCHORAGE OF LIGHT, WOOD-FRAME RESIDENTIAL BUILDINGS.

Pursuant to California Government Code sections 50022.1 to 50022.8, chapter A3 of the latest edition of the California Existing Building Code ("CEBC"), published at title 24, part 10, of the California Code of Regulations, is adopted by reference, subject to the amendments, additions and deletions set forth below. One true copy of the CEBC is on file in the office of the Building Official and is available for public inspection as required by law.

(Ord. 1538, 12-6-2016; amd. Ord. 1607, 11-19-2019)

§ 13-18-V300: VOLUNTARY EARTHQUAKE RISK REDUCTION IN WOOD-FRAME RESIDENTIAL BUILDINGS WITH SOFT, WEAK OR OPEN FRONT WALLS. Pursuant to California Government Code sections 50022.1 to 50022.8, chapter A4 of the latest edition of the California Existing Building Code ("CEBC"), published at title 24, part 10, of the California Code of Regulations, is adopted by reference, subject to the amendments, additions and deletions set forth below. One true copy of the CEBC is on file in the office of the Building Official and is available for public inspection as required by law.

(Ord. 1538, 12-6-2016; amd. Ord. 1607, 11-19-2019)

§ 13-18-V400: VOLUNTARY EARTHQUAKE HAZARD REDUCTION IN EXISTING CONCRETE BUILDINGS.

Pursuant to California Government Code sections 50022.1 to 50022.8, chapter A5 of the latest edition of the International Existing Building Code ("IEBC"), published by the International Code Council, is adopted by reference, subject to the amendments, additions and deletions set forth below. Sections A502 through A507 are amended as follows: All references to "International Building Code" shall be amended to read "latest Edition of the California Building Code ("CBC") as amended by the El Segundo Municipal Code". One true copy of the IEBC is on file in the office of the Building Official and is available for public inspection as required by law.

(Ord. 1538, 12-6-2016; amd. Ord. 1607, 11-19-2019)