Bearing Capacity of Precast High Strength Concrete Columns Connected by Mortar Joints


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Title: Bearing Capacity of Precast High Strength Concrete Columns Connected by Mortar Joints

Author(s): A. Da Silva Ramos Barboza and M.K.El Debs

Publication: Special Publication

Volume: 207


Appears on pages(s): 397-416

Keywords: connection; mortar joint; precast high strength concrete columns

Date: 10/7/2002

Mortar joints are commonly used in precast concrete structures as connection between columns, walls and load bearing precast concrete facade elements. Usually, the mortar joint has a lower strength than precast elements and its deformability tends to be larger than the ones, which causes a non-uniform distribution of stress in the joint. The mortar joint represents the weakest link in the structural system and the mortar bearing capacity limits the bearing capacity of the precast concrete elements. This paper reports on the development of an experimental program to analyze the bearing capacity of precast high strength concrete columns connected by mortar joints produced with commercially available materials, with the purpose of making better use of the columns’ bearing capacity. It was found that the thicker the joint, the lower the system’s bearing capacity, and that different strains are produced, depending on the type of material used to fill the joint - grout or dry mortar, even when the same thickness and the same relation between strengths is maintained. The conclusion reached was that it is always advisable to adopt a relation equal to or higher than one, and that a 20mm mortar layer produces an optimal behavior, in terms of both strength and ductility.