Colton Municipal Code Ch. 15.20 Seismic Strengthening for Unreinforced Masonry Buildings

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Editor's note— Ord. No. O-04-15, § 14, April 7, 2015, renumbered the former Ch. 15.14, §§ 15.14.010—15.14.050 as Ch. 15.20, §§ 15.20.010—15.20.050 and amended as set out herein. The historical notation has been retained with the amended provisions for reference purposes.

A. 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 existing Unreinforced Masonry Bearing Wall Buildings.

The provisions of this chapter are intended as minimum standards for structural seismic resistance. The provisions are established primarily to reduce the risk of life loss or injury. Compliance with these provisions will not necessarily prevent loss of life or injury or prevent earthquake damage to rehabilitated Buildings.

B. Scope. The provisions of this chapter Shall apply to all existing Buildings having at least one Unreinforced Masonry Bearing Wall. Except as provided herein, all other provisions of the 1988 Uniform Building Code, hereinafter referred to as the Building Code, Shall apply.

C. Exceptions. This chapter Shall not apply to:

1. Detached one- or Two-Family Dwellings and detached Apartment houses containing less than five Dwelling Units and Used solely for residential purposes;

2. Essential Facilities as defined in Table 23-K of the Building Code;

3. Hazardous Facilities as defined in Table 23-K of the Building Code;

4. Unreinforced Masonry Bearing Wall Buildings constructed of hollow concrete Blocks or hollow clay tiles, unless they do not exceed two stories in height and it can be shown by testing that the tile or Block units are of bearing type and the capacity of the Wall in bearing and shear based on Net Area in contact through bed joints is not less than those allowed for solid bricks. Bonding Shall also be verified to the satisfaction of the Local government agency.

D. Definitions. For the purpose of this chapter, the applicable definitions in the Building code Shall also apply. Certain other terms are defined as follows:

1. "Normal Wall" means a Wall perpendicular to the direction of seismic forces.

2. "Open Front" means an exterior Building Wall plane on one side only without vertical elements of the lateral force resisting system in one or more stories.

3. "Unreinforced Masonry (URM) Wall" means a masonry Wall in which the area of reinforcing steel is less than twenty-five percent of the minimum required by the Building code for reinforced masonry.

4. "Unreinforced Masonry Bearing Wall" means a URM Wall which provides the vertical support for a floor or roof for which the total superimposed load exceeds one hundred pounds per linear foot of Wall.

(Ord. No. O-04-15, § 14, 4-7-2015)

A. General. All Buildings Shall have a seismic resisting system conforming with Section 2303(b) of the Building code, except as modified by this chapter.

B. Alterations and Repairs. Alterations and repairs required to meet the provisions of this chapter Shall comply with all other applicable requirements of the Building code unless specifically provided for in this chapter.

C. Requirements for Plans. The Following construction information Shall be included in the plans required by this chapter:

1. Dimensioned floor and roof plans showing existing Walls and the size and spacing of floor and roof framing meters and sheathing Materials. The plans Shall indicate all existing and new crosswalls and their Materials of construction. The location of the crosswalls and their openings Shall be fully dimensioned or drawn to scale on the plans;

2. Dimensioned Wall Elevations showing openings, piers, Wall classes, thicknesses, heights, Wall shear test locations, and cracks or damaged portions requiring repairs; the general condition of the mortar joints and if and where the joints require pointing. Where the exterior face is veneer, the type of veneer, its thickness and its bonding and/or ties to the structural Wall masonry Shall also be reported;

3. The type of interior Wall and ceiling surfaces;

4. The extent and type of existing Wall anchorage to floors and roof when utilized in the design;

5. The extent and type of Parapet corrections which were previously performed, if any;

6. Repair details, if any, of cracked or damaged unreinforced masonry Walls required to resist forces specified in this chapter;

7. All other plans, sections, and details necessary to delineate required retrofit construction including those items in Section 15.14.050.

(Ord. No. O-04-15, § 14, 4-7-2015)

A. General. All Materials Permitted by this chapter, including their appropriate allowable design values, and those existing configurations of Materials specified herein, May be utilized to meet the requirements of this chapter.

B. Existing Materials. All existing Materials utilized as Part of the required force resisting system Shall be in sound condition or Shall be repaired or removed and replaced with new Material.

(Ord. No. O-04-15, § 14, 4-7-2015)

A. Pointing. All preparation and mortar pointing Shall be performed with special inspection.

Exception: At the discretion of the Building Official, Incidental pointing May be performed without special inspection.

B. Masonry Shear Tests. In-place masonry shear tests Shall comply with UBC Standard No. 24-40.

C. Existing Wall Anchors. Existing Wall anchors utilized as all or Part of the required tension anchors Shall be tested in pullout according to UBC Standard No. 24-41. The minimum number of anchors tested Shall be four per floor, with two tests at Walls with joists framing into the Wall and two tests at Walls with joists parallel to the Wall, but not less than ten percent of the total number of existing tension anchors at each level.

D. New Bolts. One-fourth of all new shear Bolts and combined tension and shear Bolts in unreinforced masonry Walls Shall be tested according to UBC Standard No. 24-41.

Exception: Special inspection in accordance with the Building code May be provided during installation in lieu of testing.

(Ord. No. O-04-15, § 14, 4-7-2015)

A. Wall Anchorage.

1. Anchor Locations. All unreinforced masonry Walls Shall be anchored at the roof and floor levels. Ceilings with substantial rigidity and abutting masonry Walls Shall be connected to Walls with tension Bolts at a maximum anchor spacing of six feet. Ceiling systems with substantial mass Shall be braced at the ceiling perimeter to the roof or floor diaphragms.

2. Anchor Requirements. Anchors Shall be tension Bolts through the Wall by an Approved equivalent at a maximum anchor spacing of six feet. All existing Wall anchors Shall be Secured to the joists to develop the required forces.

3. Minimum Wall Anchorage. Anchorage of masonry Walls to each floor or roof Shall resist a minimum force determined by Section 2312(g)2 of the Building code or two hundred pounds per linear foot, whichever is greater, acting normal to the Wall at the level of the floor or roof. Existing Wall anchors, installed under previous Permits, Must meet or Must be upgraded to meet the requirements of this chapter.

4. Anchors at Corners. At the roof and all floor levels, both shear and tension anchors Shall be provided within two feet horizontally from the inside of the corners of the Walls.

5. Anchors with Limited Access. When Access to the exterior face of the masonry Wall is prevented by proximity of an existing Building, Wall anchors conforming to Item 6b in Table No. A1-D May be Used.

B. Diaphragm Shear Transfer. Shear Bolt spacing Shall have a maximum Bolt spacing of six feet.

(Ord. No. O-04-15, § 14, 4-7-2015)