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Project 2011-01

Project Title:

Investigation of the Strength of Lap Splices of Deformed Bars in Thin Reinforced Concrete Members Subjected to Tension

Institution:

Purdue University
West Lafayette, Indiana

Researchers:

Dr. Santiago Pujol
Brian Richter

Award Period:

2011-2012 school year

Status:

Completed - Click here to download the Research Note

Description:

The current design provisions for lap splices and development length of deformed bars in tension (ACI 318-08) were developed mainly from tests conducted on beams with “solid” cross sections (Orangun et al. 1977, Sozen and Moehle 1990). By “solid” cross sections we refer to sections in which the concrete is continuous between the tension reinforcement and the extreme concrete fiber in compression (which is the case in most flexural members). In these sections, all bars in tension, except the corner bars, are close to a single concrete surface. Limited tests have been done in which lap splices are located in elements within “thin” walls in tension (Brueggen 2010, Johnson 2010). By “thin” walls we refer to segments of cross sections in which all bars are close to two free surfaces (Fig. 1). A number of recent structural failures evidence the vulnerability of reinforced concrete structures with lap splices in thin members; in other words, elements meeting the latter description.

The strength of lap splices of deformed bars in thin reinforced concrete members subjected to tension is being investigated in this project. In thin elements, more bars are located close to the concrete surface, making it easier for splitting cracks to form a complete failure plane. This condition can reduce the strength of the lap splice. The Purdue study looked at three test specimen types: wall sections, lap splice coupons, and lap splice beams.