SEISMIC DESIGN OF MASONRY BUILDINGS

Background information A 7 storey unreinforced brick masonry (office) building (Figure 1) was designed and cons tructed in 1905 prior to the introduction of seismic design requirements. During a recent earthquake (M7.1) it suffered some damage to the masonry piers in the external walls on the North and West sides of the building (refer Figure 1(b)). As part of the e mergency response, the disaster management team sent some structural engineers to assess the damage and determine whether the building posed a hazard to other buildings, pedestrians and vehicles in the vicinity. The consensus was that it posed a significan t falling hazard and that the roads in both directions should be blocked until the building is repaired or demolished. The city council is not happy with this recommendation they want the city re opened and accessible to the public as soon as possible. N ow, it has been discovered that the building has an internal network of steel columns and beams that support the timber floors so perhaps the brick piers along the north and west walls only have to resist their own seismic forces and gravity loads. 1) (20%) An Executive Summary describing (1 page maximum): the results of your structural assessment (axial, in-plane shear and out-of-plane bending capacity versus demand for the critical panels (A, B, C & D) in each wall at the lowest and top storeys that contain masonry panels; and A brief description of a possible retrofit strategy for the building. 2) (80%) Detailed (excel and hand calculation) Seismic Assessment for earthquake loading in the north-south direction of the West Wall and earthquake loading in the east-west direction of the North Wall. Don’t forget, URM walls in the out-of-plane (bending) direction are treated as “architectural components” of buildings in AS1170.4 and the procedure to calculate the seismic demand on them for out-of-plane bending is given in Section 8 of AS 1170.4. AS