Concrete Shear Wall Construction

Buildings with cast-in-situ reinforced concrete shear walls are widespread in many earthquake-prone countries and regions, such as Canada, Chile, Romania, Turkey, Colombia, the republics of the former Soviet Union, etc. This type of construction has been practiced since the 1960s in urban regions for medium- to high-rise buildings (4 to 35 stories high). Shear wall buildings are usually regular in plan and in elevation. However, in some buildings, lower floors are used for commercial purposes and the bu
ildings are characterized with larger plan dimensions at those floors. In other cases, there are setbacks at higher floor levels. Shear wall buildings are commonly used for residential purposes and can house from 100 to 500 inhabitants per building.

STRUCTURAL FEATURES

The lateral and gravity load-resisting system consists of reinforced concrete walls and reinforced concrete slabs. Shear walls are the main vertical structural elements with a dual role of resisting both the gravity and lateral loads. Wall thickness varies from 140 mm to 500 mm, depending on the number of stories, building age, and thermal insulation requirements. In general, these walls are continuous throughout the building height;
however, some walls are discontinued at the street front or basement level to allow for commercial or parking spaces. Floor slabs are either cast-in-situ flat slabs, or, less often, precast hollow-core slabs. Slab thickness varies from 120 mm in the republics of the former Soviet Union, to 220 mm (the latter value corresponds to
hollow-core slab used in Kyrgyzstan and other parts of the former Soviet Union). Buildings are supported by concrete strip or mat foundations; the latter type is common for buildings with basements. Structural modifications are not very common in this type of construction.

Code requirements, related to the seismic forces the shear wall buildings are designed for, depend on the seismicity of the building site, the method of analysis used, and the countryspecific seismic design provisions. For example, the Chilean seismic code prescribes a base shear coefficient for shear wall buildings of 5 to 6.7%, depending on the seismic zone. The maximum allowed lateral-story drift is limited to 0.002 according to both the Chilean and Canadian seismic requirements for regular buildings and to 0.005 according to the
Colombian seismic code (NSR-98). Reinforcement requirements are based on building code requirements specific for each country. In general, the wall reinforcement consists of two layers of distributed reinforcement (horizontal and vertical) throughout the wall length. In addition, vertical reinforcement bars are provided close to the door and window openings, as well as at the wall end zones (also known as boundary elements or barbells).

Wall reinforcement details: (left) Canada ; (right) Kyrgyzstan