Page 102 - ICC IEBC 2018

Appendix A: Guidelines for the Seismic Retrofit of Existing Buildings

CHAPTER A1

SEISMIC STRENGTHENING PROVISIONS
FOR UNREINFORCED MASONRY BEARING WALL BUILDINGS

User note:
About this appendix: Appendix A provides guidelines for upgrading the seismic-resistance capacity of different types of existing buildings. It
is organized into separate chapters that deal with buildings of different types, including unreinforced masonry buildings, reinforced concrete
and reinforced masonry wall buildings, and light-frame wood buildings.

SECTION A101 [BS] CROSSWALL. A new or existing wall that meets the
PURPOSE requirements of Section A111.3. A crosswall is not a shear
[BS] A101.1 Purpose. The purpose of this chapter is to pro- wall.
mote public safety and welfare by reducing the risk of death [BS] CROSSWALL SHEAR CAPACITY. The unit shear
or injury from the effects of earthquakes on existing unrein- value times the length of the crosswall, ν L .
c c
forced masonry bearing wall buildings. [BS] DETAILED BUILDING SYSTEM ELEMENTS.
The provisions of this chapter are intended as minimum The localized elements and the interconnections of these ele-
standards for structural seismic resistance, and are established ments that define the design of the building.
primarily to reduce the risk of life loss or injury. Compliance [BS] DIAPHRAGM EDGE. The intersection of the horizon-
with these provisions will not necessarily prevent loss of life tal diaphragm and a shear wall.
or injury, or prevent earthquake damage to retrofitted build-
ings. [BS] DIAPHRAGM SHEAR CAPACITY. The unit shear
value times the depth of the diaphragm, ν D.
u
[BS] FLEXIBLE DIAPHRAGM. A diaphragm of wood or
SECTION A102 untopped metal deck construction in which the horizontal
SCOPE deformation along its length is at least two times the average
story drift.
[BS] A102.1 General. The provisions of this chapter shall
apply to all existing buildings not more than six stories in HEAD JOINT. The vertical mortar joint placed between
height above the base of the structure and having not fewer masonry units within the wythe.
than one unreinforced masonry bearing wall. The elements [BS] NORMAL WALL. A wall perpendicular to the direc-
regulated by this chapter shall be determined in accordance tion of seismic forces.
with Table A102.1. Except as provided herein, other struc- [BS] OPEN FRONT. An exterior building wall line on one
tural provisions of the building code shall apply. This chapter side only without vertical elements of the seismic force-
does not apply to the alteration of existing electrical, plumb- resisting system in one or more stories.
ing, mechanical or fire safety systems.
[BS] POINTING. The process of removal of deteriorated
[BS] A102.2 Essential and hazardous facilities. The provi-
mortar from between masonry units and placement of new
sions of this chapter shall not apply to the strengthening of mortar. Also known as repointing or tuckpointing for pur-
buildings in Risk Category III or IV. Such buildings shall be poses of this chapter.
strengthened to meet the requirements of the International
[BS] REPOINTING. See “Pointing.”
Building Code for new buildings of the same risk category or
other such criteria approved by the code official. [BS] RIGID DIAPHRAGM. A diaphragm of concrete con-
struction or concrete-filled metal deck construction.
[BS] TUCKPOINTING. See “Pointing.”
SECTION A103
DEFINITIONS [BS] UNREINFORCED MASONRY (URM). Includes
burned clay, concrete or sand-lime brick; hollow clay or
[BS] A103.1 Definitions. For the purpose of this chapter, the concrete block; plain concrete; and hollow clay tile. These
applicable definitions in the building code shall also apply.
materials shall comply with the requirements of Section
[BS] BED JOINT. The horizontal layer of mortar on which a A106 as applicable.
masonry unit is laid.
[BS] UNREINFORCED MASONRY BEARING WALL.
[BS] COLLAR JOINT. The vertical space between adjacent A URM wall that provides the vertical support for the reac-
wythes. A collar joint may contain mortar or grout. tion of floor or roof-framing members for which the total

2018 INTERNATIONAL EXISTING BUILDING CODE ® 83
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