Strengthening of Unreinforced Masonry Buildings

Abstract

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 and 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. (Ord. 5921 § 1, 1991) Section 16.17.020 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 Building Code shall apply. Exceptions: 1. Detached one-or two-family dwellings and detached apartment houses containing less than five dwelling units and used solely for residential purposes. 2. Wood framed structures two stories or less in height supported by unreinforced masonry foundation walls of less than thirty inches in height. 3. This chapter shall not apply to "Essential facilities" and "Hazardous facilities" as defined in Table No. 23-K of the Building Code. 4. Buildings such as warehouses, mausoleums, crypts, or other similar structures where human occupancy is low and infrequent as determined by the Building Official. This chapter does not require alteration of existing electrical, plumbing, mechanical or fire safety systems unless they are removed or altered during the seismic retrofit process. (Ord. 5921 § 1, 1991) Section 16.17.025 Definitions. For the purpose of this chapter, the applicable definitions in the Building Code shall also apply. "Collar joint" is the vertical space between adjacent wythes and may contain mortar. "Crosswall" is a wall that meets the requirements of Section 16.17.055(D)(3).

Applicability of Cu-Al-Mn shape memory alloy bars to retrofitting of historical masonry constructions

“…Reinforced core technique, wherein reinforcing steel bars are inserted vertically into holes drilled at the center of URM walls as shown in Fig. 1(d), is often suitable for retrofitting historical masonry constructions because the technique does not change the appearance of URM walls and enhances both strength and ductility (Plecnik et al 1986, Abrams et al 2007. In reinforced core technique, however, the use of steel bars as reinforcing elements may lead to pinching, or degradation of stiffness and strength under cyclic loading.…”

Effective techniques for restoration of heritage masonry

“…This technique is also used to provide shear reinforcement in the horizontal direction. Using centre coring, the in-plane shear resistance of brick masonry walls was found to increase by 56% to 111% (Plecnik et al, 1984). It should be noted that the introduction of reinforcement may drastically change the structural response of a building.…”

Effectiveness of superelastic bars for seismic rehabilitation of clay‐unit masonry walls

“…There have been extensive research works in developing techniques for improving seismic behavior of unreinforced masonry (URM) walls . Typical examples of such techniques involve attachment of reinforcing members, surface treatment, grout injection, post‐tensioning, and reinforced core technique.…”