(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 Table I or by approved equivalent at a maximum anchor spacing of six feet. All unreinforced masonry walls shall be anchored at all floors with tension bolts through the wall or by existing rod anchors at the maximum anchor spacing of six feet.
(a) All existing rod anchors shall be secured to the joists to develop the required forces. The Building Official may require testing to verify the adequacy of the embedded ends of existing rod anchors tests when required shall conform to § 15.64.100(H).
(b) When access to the exterior face of the masonry wall is prevented by proximity of an existing building, wall anchors conforming to Items 5 and 6 in Table I may be used.
(c) Alternative devices to be used in lieu of tension bolts for masonry wall anchorage shall be tested as specified in § 15.64.100(I).
(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, ledgers 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 insure 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 (masonry cements shall not be used). 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 special inspector certified to inspect masonry or concrete. At the conclusion of the project, the inspector shall submit a written report to the Building Official setting forth the portion of work inspected.
(6) Repair details shall be prepared for 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, if any, which were performed in accordance with the Uniform Building Code;
(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 whether reinstalling or anchoring of ceiling plaster is necessary;
(7) The general condition of the mortar joints and whether the joints need pointing;
(8) Site plan.
(`78 Code, § 15.64.110.)
TABLE A RATING CLASSIFICATIONS | |
TYPE OF BUILDING | CLASSIFICATION |
Essential Building | I |
High Risk Building | II |
Medium Risk Building | III |
Low Risk Building | IV |
TABLE B TIME LIMITS FOR COMPLIANCE (1) | |||
REQUIRED ACTION BY OWNER | OBTAIN BUILDING PERMIT WITHIN | COMMENCE CONSTRUCTION WITHIN | COMPLETE CONSTRUCTION WITHIN |
Complete structural alterations or building demolition | 1 year | 180 days (2) | 3 years |
Wall anchor installation | 180 days | 270 days | 1 year |
(1) Where two or more buildings under separate ownership are to be rehabilitated simultaneously, an extension can be based on the average time requirements for the buildings involved, with a suggested minimum extension of six months. An extension could be granted on submission of a binding agreement between the owners involved with the actual date of compliance to be determined by the Building Official.
(2) Measured from date of building permit issuance. All the other time permits are measured from the date of the order.
TABLE C SERVICE PRIORITIES AND EXTENDED TIME PROVISIONS | |||
Rating Classification | Occupant Load | Extension of Time if Wall Anchors are Installed | Minimum Time Periods for Service of Order |
I (Highest Priority) | Any | 1 year | 0 |
II | 100 or more 100 or more | 3 years 5 years | 90 days 1 year |
III | 51 to and including 99 20 to and including 50 | 6 years 6 years | 2 years 3 years |
IV (Lowest Priority) | Less than 20 | 7 years | 4 years |
TABLE D HORIZONTAL FACTORS BASED ON RATING CLASSIFICATION | |
RATING CLASSIFICATION | IKCS |
I | 0.186 |
II | 0.133 |
III & IV | 0.100 |
TABLE E HORIZONTAL FORCE FACTORS "IS" FOR PARTS OR PORTIONS OF STRUCTURES | |
RATING CLASSIFICATION | IS |
I | 1.50 |
II | 1.00 |
III & IV | 0.75 |
TABLE F HORIZONTAL FORCE FACTOR "Cp " FOR PARTS OR PORTIONS OF BUILDINGS OR OTHER STRUCTURES(1)
Part or Portion of Buildings | Direction of Force | Value of Cp |
Exterior bearing and nonbearing walls, interior bearing walls and partitions, interior nonbearing walls and partitions over ten feet in height, masonry fences over six feet in height. | Normal to Flat Surface | 0.20 |
Cantilever parapet and other cantilever walls, except retaining walls. | Normal to Flat Surface | 1.00 |
Exterior and interior ornamentations and appendages. | Any Direction | 1.00 |
When connected to or a part of a building, towers, tanks, towers and tanks, plus contents, racks over 8 feet 3 inches in height plus contents, chimneys, smokestacks and penthouses. | Any Direction | 0.20(2)(4) |
When connected to or a part of a building: rigid and rigidly mounted equipment and machinery not required for continued operation of essential occupancies. (5) | Any Horizontal Direction | 0.20(3) |
Tanks plus effective contents resting on the ground. | Any Direction | 0.12 |
Floors and roofs acting as diaphragms. | In the plane of the diaphragm | 0.12(6) |
Prefabricated structural elements, other than walls, with force applied at center of gravity of assembly. | Any Horizontal Direction | 0.30 |
Connections for exterior panels or elements. | Any Direction | 2.00 |
(1) See § 15.64.090(B) for use of Cp.
(2) When located in the upper portion of any building with a hn/D ratio of 5 to 1 or greater, the value shall be increased by 50%.
(3) For flexible and flexibly mounted equipment and machinery, the appropriate values for Cp 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.
(4) The Wp for storage racks shall be the weight of the racks plus contents. The value of Cp for racks over two storage support levels in height shall be 0.16 for the levels below the top two levels.
(5) 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 § 2312(k)).
(6) Floor and roofs acting as diaphragms shall be designed for a minimum force resulting from a Cp of 0.12 applied to Wp unless a greater force results from the distribution of lateral forces in accordance with § 2312(e).
TABLE G ALLOWABLE VALUE OF HEIGHT-THICKNESS RATIO
OF UNREINFORCED MASONRY WALLS WITH MINIMUM QUALITY MORTAR (1) (2)
OF UNREINFORCED MASONRY WALLS WITH MINIMUM QUALITY MORTAR (1) (2)
Building with Crosswalls as Defined by § 15.64.040 | All Other Buildings | |
Walls of One Story Building | 16 | 13 |
First Story Wall of Multi-Story Buildings | 16 | 15 |
Walls in Top Story of Multi-Story Buildings | 14 | 9 |
All Other Walls | 16 | 13 |
(1) Minimum quality mortar shall be determined by laboratory testing in accordance with § 15.64.100(E).
(2) Table G is not applicable to buildings of rating classification I. Walls of buildings within rating classification I shall be analyzed in accordance with § 15.64.090(F).
TABLE H VALUES FOR EXISTING MATERIALS
EXISTING MATERIALS OR CONFIGURATION OF MATERIALS (1) | ALLOWABLE VALUES |
Horizontal diaphragms a. Roofs with straight sheathing and roofing applied directly to sheathing. b. Roofs with diagonal sheathing and roofing applied directly to the sheathing. c. Floors with straight tongue and groove sheathing. d. Floors with straight sheathing and finished wood flooring. e. Floors with diagonal sheathing and finished wood flooring. f. Floors or roofs with straight sheathing and plaster applied to the joist or rafters. (2) | 100 lbs. per foot for seismic shear. 400 lbs. per foot for seismic shear. 150 lbs. per foot for seismic shear. 300 lbs. per foot for seismic shear. 450 lbs. per foot for seismic shear. Add 50 lbs. per foot to the allowable values for Items 1a and c. |
Shear Walls Wood stud walls with lath and plaster. | 100 lbs. per foot each side for seismic shear. |
Plain Concrete Footings | fc = 1500 psi unless otherwise shown by tests. |
Douglas Fir Wood | Allowable stress same as No. 1 D.F. (3) |
Reinforcing Steel | Ft = 18,000 lbs. per square inch maximum. (3) |
Structural Steel | Ft = 20,000 lbs. per square inch maximum. (3) |
(1) Material must be sound and in good condition.
(2) The wood lath and plaster must be reattached to existing joists or rafters in a manner approved by the Department.
(3) Stresses given may be increased for combinations of loads as specified in § 15.64.090(G)(2).
TABLE I ALLOWABLE VALUES OF NEW MATERIALS USED IN CONJUNCTION WITH EXISTING CONSTRUCTION I
NEW MATERIALS OR CONFIGURATION OF MATERIALS | ALLOWABLE VALUES |
NEW MATERIALS OR CONFIGURATION OF MATERIALS | ALLOWABLE VALUES |
Horizontal Diaphragms Plywood sheathing applied directly over existing straight sheathing with ends of plywood sheets bearing on joints or rafters and edges of plywood located on center of individual sheathing boards. | Same as specified in Table No. 25-J of this code for blocked diaphragms. |
Shear Walls a. Plywood sheathing applied directly over existing wood studs. No value shall be given to plywood applied over existing plaster or wood sheathing. b. Dry wall or plaster applied directly over existing wood studs. c. Dry wall or plaster applied to plywood sheathing over existing wood studs. | Same as values specified in Table No. 25-K for shear walls. 75% of the values specified in Table No. 47-I. 33% of the values specified in Table No. 47-I. |
Shear Bolts Shear bolts and shear dowels embedded a minimum of 8 inches into unreinforced masonry walls. Bolt centered in a 2½ inch diameter hole with dry-pack or nonshrink grout around circumference of bolt or dowel. (1) | 100% of the values for solid masonry specified in Table No. 24E. No values larger than those given for ¾ inch bolts shall be used. |
Tension Bolts Tension bolts and tension dowels extending entirely through unreinforced masonry walls secured with bearing plates on far side of wall with at least 30 sq. inches of area. (2) | 1200 lbs. per bolt or dowel. |
Bolts extending to the exterior face of the wall with a 2½ inch round plate under the head. Installed as specified for shear bolts. Spaced not closer than 12 inches on centers. (1) (2) Bolts or dowels extending to the exterior face of the wall with a 2½ inch round plate under the head and drill at an angle of 22½ degrees to the horizontal. Installed as specified for shear bolts. (1) (2) | 600 lbs. per bolt. 1200 lbs. per bolt or dowel. |
Infilled Walls Reinforced masonry infilled openings in existing unreinforced masonry walls with keys or dowels to match reinforcing. | Same as values specified for unreinforced masonry walls. |
Reinforced Masonry Masonry piers and walls reinforced per Section 2407. | Same values as specified in Division 26, UBC. |
Reinforced Concrete Concrete footings, walls and piers reinforced as specified in Division 26 and designed for tributary loads. | Same values as specified in Division 26, UBC. |
Existing Foundation Loads Foundation loads for structures exhibiting no evidence of settlement. | Calculated existing foundation loads due to maximum dead load plus live load may be increased for 25% for dead load and may be increased 50% for dead load plus seismic load required by this Division. |
NOTES:
(1) Bolts and dowels to be tested as specified in Section 8808(f).
(2) Bolts and dowels to be ½ inch minimum in diameter.
TABLE J ALLOWABLE SHEAR STRESS FOR TESTED UNREINFORCED MASONRY WALLS
80% of Test Results in psi not less than | Average Test Results of Cores in psi | Seismic In-plane Shear Based on Gross Area (1) |
30 plus axial stress | 20 | 3 psi |
40 plus axial stress | 27 | 4 psi |
50 plus axial stress | 33 | 5 psi |
100 plus axial stress or more | 67 or more | 10 psi max |
(1) Allowable shear stress may be increased by addition of 10% of the axial stress due to the weight of the wall directly above.
GLOSSARY OF SYMBOLS AND NOTATIONS
C Numerical coefficient as specified in Section 2312(d)
CP Numerical coefficient as specified in Section 2312(g) and as set forth in Table No. 23-J
D The dimension of the structure, in feet, in a direction parallel to the applied forces
fc Specified compressive strength of concrete, psi
Fp Lateral forces on a part of the structure and in the direction under consideration
ft Allowable tensile stress, psi
hn Height in feet above the base to level n
I Occupancy importance factor as set forth in Table No. 23-K
S Numerical coefficient for site-structure resonance
V The total lateral force or shear at the base
W The total dead load as defined in Section 2302, including the partition loading specified in Section 2304(d) where applicable
WP The weight of a portion of a structure or nonstructural component
Z Numerical coefficient dependent upon the zone as determined by Figure No. 1 of Chapter 23. All areas in California are classified in Zones 3 or 4. For locations in Zone No. 3, Z = ¾. For locations in Zone No. 4, Z = 1.
(`78 Code, § 15.64.110.) (Ord. 1967 § 1 (part), 1989.)