1.0. The value of W shall be — San Jose Municipal Code

Lateral Forces on Elements of Structures.

Parts or portions of buildings shall be analyzed and designed for lateral loads in accordance with Chapter 23 of the 1985 Uniform Building Code but not less than the value from the following equation: Fp = ICpSWp.

This equation shall hereinafter be referred to as Formula (A1-2).

For the provisions of this section, the product of I and S shall equal 1.0. The value of Cp shall be in accordance with Table 23-J of the 1985 Uniform Building Code. The value of Wp shall be as defined in Chapter 23 of the 1985 Uniform Building Code.

Exception: Unreinforced masonry walls may be designed in accordance with Section 17.40.330.

Regulated Elements of Buildings. The elements of buildings required to be analyzed by this chapter include:

Height-to-thickness ratio of masonry walls;

Tension bolts in bending;

In-plane shear stress;

Parapets; and

Diaphragm stresses and diaphragm chords in floors and roof.

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 the 1985 Uniform Building Code and Formula (A1-2) of subsection B.1 of this section. Masonry walls shall be anchored to all floors and roof to resist a minimum force of two hundred pounds per linear foot acting normal to the wall at the level of the floor or roof.

Level of Required Repair. Alterations and repairs required to meet the provisions of this chapter shall comply with all other applicable requirements of the 1985 Uniform Building Code except as specifically provided in this part.

Required Analysis.

General.

Except as modified herein, the analysis and design relating to the structural alteration of existing buildings within the scope of this part shall be in accordance with the analysis specified in the 1985 Uniform Building Code. In addition the compatibility of the roof diaphragm stiffness with the out-of-plane stability of the unreinforced masonry bearing walls of the story immediately below the roof shall be verified in accordance with the provisions of Section 17.40.350.

Exception: Buildings with rigid concrete or steel and concrete roof diaphragms shall use the h/t values for all other buildings in Table No. 1.

TABLE NO. 1 ALLOWABLE VALUE OF HEIGHT- THICKNESS (h/t) RATIO OF UNREINFORCED MASONRY WALLS WITH MINIMUM QUALITY MORTAR 1

Buildings with Complying All Other Buildings
Cross Walls

One story building walls 13-16 2, 3, 4 13

First story of multi-story 16 15 buildings

Walls in the top story of multi- 9-14 2, 3, 4 9 story buildings

All other walls 16 13

Minimum mortar quality shall be determined by laboratory testing in accordance with this chapter.

The minimum mortar shear strengths required in the following footnotes 3 and 4 shall be that shear strength without the effect of axial stress in the wall at the point of the test.

The larger height-to-thickness ratio may be used where mortar shear tests in accordance with Section 17.40.330D establish a minimum mortar shear strength of not less than one hundred psi or where the tested mortar shear strength is not less than sixty psi and a visual examination of the vertical wythe-to- wythe wall joint (collar joint) indicates not less than fifty percent mortar coverage.

Where a visual examination of the collar joint indicates not less than fifty percent mortar coverage and the minimum mortar shear strength when established in accordance with Section 17.40.330D is greater than thirty psi but less than sixty psi, the allowable height-to-thickness ratio may be determined by linear interpolation between the larger and smaller ratio values in direct proportion to the mortar shear strength.

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

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

Analysis Procedure.

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 1985 Uniform Building Code and those materials and types of construction specified in Section 17.40.330.

Connections. Materials and connectors used for the interconnection of parts and portions of the structure shall conform to the requirements of the 1985 Uniform Building Code. Nails may be used as a part of an approved connector.

Unreinforced Masonry Walls.

In addition to the analysis of seismic forces required by this chapter, unreinforced masonry walls shall be analyzed as specified in the 1985 Uniform Building Code to withstand all vertical loads as specified in the 1985 Uniform Building Code. Such walls shall meet the minimum requirements set forth in the 1985 Uniform Building Code.

Exception: When calculating shear or diagonal tension stresses due to seismic forces, existing masonry shear walls may be designed to resist 1.0 times the required forces in lieu of the 1.5 factor required by the 1985 Uniform Building Code.

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

ii.

Exceptions: (i) Unreinforced masonry walls may be analyzed in accordance with Section 17.40.330; (ii) unreinforced masonry walls which carry no design loads other than their own weight may be considered veneer if they are adequately anchored to new supporting elements.

Substantial changes in wall thickness or stiffness shall be considered in the analysis for out-of-plane and in-plane wall stability; and the wall shall be restrained against out-of-plane instability by anchorage and bracing to the roof or floor diaphragm in accordance with subsection D of this section.

Exception: Variations in wall stiffness caused by nominal openings such as windows and doors need not be considered.

Combination of Vertical and Seismic Forces.

New Materials. All new materials introduced into the structure to meet the requirements of this section which are subject to combined vertical and horizontal forces shall comply with the 1985 Uniform Building Code.

Existing Materials. When stress in existing lateral force resisting elements is due to a combination of dead loads plus live loads plus seismic loads, the allowable working stress specified in the 1985 Uniform Building Code may be increased one hundred percent. However, no increase will be permitted in the stresses allowed in Section 17.40.330. The stresses in elements due to only seismic and dead loads shall not exceed the values permitted by the 1985 Uniform Building Code.

Allowable Reduction of Bending Stress by Vertical Load. Calculated tensile fiber stress may be reduced by the full direct stress due to vertical dead loads.

(Ord. 23766.)