Title:
Concrete Q & A: Splice Length Anomaly
Author(s):
David Darwin
Publication:
Concrete International
Volume:
27
Issue:
10
Appears on pages(s):
96
Keywords:
DOI:
Date:
10/1/2005
Abstract:
We recently noticed an anomaly in the equations for computing lap splice lengths in columns with uncoated, Grade 75 (Grade 520), No. 11 (36 mm) reinforcing bars. For normalweight concrete with a compressive strength of 9000 psi (62 MPa), we calculated a Class B tension lap splice length of 56 in. (1425 mm), using (c + Ktr)/db = 1.93, and a compression lap splice length of 61 in. (1550 mm). It does not seem correct that a compression lap splice would ever be longer than a Class B tension lap splice. Is something wrong with one of the equations? The discrepancy would be even larger if we used a (c + Ktr)/db value greater than 1.93.