Glossary

Anchor Ties or bolts: Generally threaded rods or bolt which connect walls to floor and roof framing. Washers, plates, or rosettes anchor the bolt in place.

Base isolation: the ability to isolate the structures from the damaging effects of earthquakes by providing a flexible layer between the foundations and vertical supports.

Diagonal Braces: the use of diagonal, chevron or other type of bracing (X or K) to provide lateral resistance to adjacent walls.

Core drilling: a type of vertical reinforcement of masonry walls that relies on drilling a continuous vertical core that is filled with steel reinforcing rods and grouting to resist in-plane shear and out-of-plane bending.

Cripple wall: A frame wall between a building’s first floor and foundation.

Diaphragm: A floor, roof, or continuous membrane that provides for the transfer of earthquake loading to the exterior or interior shear walls of the structure.

Fiber wrap reinforcement: A synthetic compound of filaments that increase the shear capacity of structural members.

Grouted bolts: anchor bolts set, generally on an angle, in a concrete grout mixture, avoid the problem of using an exposed washer. Requires a greater diameter hole than an anchor bolt with washer.

Lateral forces: Generally the horizontal forces transferred to the building from the dynamic effects of wind or seismic forces.

Life-safety: providing a level of assurance that risk of loss of life is kept to minimal levels. For buildings, this includes strengthening to reduce 1)structural collapse, 2) falling debris, 3)blocking exits or emergency routes, and 4) prevention of consequential fire.

Moment-resisting frame: A steel frame designed to provide in-plane resistance to lateral loads particularly by reinforcing the joint connection between column and beams without adding a diagonal brace. Often used as a perimeter frame around storefronts or large door and window openings.

Seismic retrofit: All measures that improve the earthquake performance of a building especially those that affect structural stability and reduce the potential for heavy structural damage or collapse.

Shear stress: A concept in physics where forces act on a body in opposite directions, but not in the same line. Horizontal forces applied to a wall that is insufficient to move with these forces will crack, often in a diagonal or X pattern. Connections at beams and walls will also crack from shear stress.

Shear wall: A wall deliberately designed to transfer the building’s loads from the roof and floors to the foundation thereby preventing a building from collapse from wind or earthquake forces.

Unreinforced Masonry (URM): This designation refers to traditional brick, block,and adobe construction that relies on the weight of the masonry and the bonding capacity of mortar to provide structural stability.