Title:
Estimating the Two-Way Shear Strength of Large Reinforced Concrete Pile Caps
Author(s):
Lucas Laughery
Publication:
Web Session
Volume:
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
4/2/2023
Abstract:
Due to increasing demands, structures today are being built at scales which far exceed experience. Tall structures in particular often require deep foundations with thick reinforced concrete caps, with thicknesses that exceed what has been tested in the past. In the United States, strength of such pile caps is calculated according to ACI 318 provisions, which include a size effect factor, which puts a penalty on unit shear strength that is proportional to effective depth for sections lacking minimum shear reinforcement. This strength reduction is calibrated to databases for which tests do not vary across a large scale, and for which key unitless ratios are not always controlled. The present study fills this need using new laboratory testing capabilities. Here, we present test results of twelve tripod pile caps with effective depths of 250 mm, 500 mm, and 1000 mm (9.84 in., 19.7 in., and 39.4 in.). Other parameters such as reinforcement grade and geometry were tightly controlled to maintain constant unitless ratios across these tests. Results suggest the new ACI 318-19 size effect factor may underestimate strength of deep pile caps.