Report # 5 : Reinforced Clay/Concrete Block Masonry Building

by Ofelia Moroni, Cristian Gomez, Maximiliano Astroza

This is a rather recent construction practice followed since 1970, and it has been widely used for dwellings and up to 4-story-high apartment buildings. Buildings of this type can be found both in urban and rural areas of Chile. The main load-bearing elements are masonry walls reinforced with vertical steel reinforcement bars and placed in the hollow cores of clay masonry units (hollow clay tiles) or concrete blocks. Horizontal reinforcement bars are placed in horizontal bed joints. Masonry shear walls are tied together at floor levels by means of reinforced concrete beams in a regular structural layout. Stiffness distribution both in plan and elevation is uniform. Prior to 1986, there was no seismic design code for this structural type. During the March 3, 1985 Llolleo earthquake, performance of buildings of this type was rather poor, mainly due to construction problems, such as partial grouting in the hollow cores with reinforcement, poor quality of the mortar, and lack of horizontal reinforcement. Following the earthquake, the Chilean Design Code NCh1928 code was published based on the U.S. Uniform Building Code (UBC-1979) and on the seismic performance of this construction type reported in previous earthquakes. Since 1993, when the last version of NCh1928 was published, and more restricted requirements were enforced, the use of this type of construction has been less frequent, in part because of economic reasons.

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