Analysis of nodal stress on reinforced concrete two-pile caps supported on steel piles

Rodrigo Gustavo Delalibera,Vitor Freitas Gonçalves,Marco Aurélio Tomaz,José Samuel Giongo

doi:10.1590/s1983-41952020000600012

Rodrigo Gustavo Delalibera, Vitor Freitas Gonçalves + Show 2 more

Open Access

https://doi.org/10.1590/s1983-41952020000600012

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Abstract

abstract: Reinforced concrete pile caps may be designed trough plastic models (strut and tie model) or models based on bending theory. The formulae available for verifying the stress is based on caps supported on concrete piles, with few studies about the stress distribution on caps supported on steel piles. To analyze the structural behavior of caps supported on steel piles, as well as the stress on the superior and inferior nodal zones, four two-pile caps supported on steel piles were tested. The variables were the embedment length and in one of the specimens a steel plate was welded on top of both piles. It was observed that the embedment length has substantial influence on pile cap structural behavior. It was concluded that, to verify the stress on inferior nodal zone of the cap, aside from pile area, an area of concrete confined between the flaps of the pile must be considered.

Highlights

According to NBR 6118: 2014 [1], pile caps are volumetric structural elements whose function is to transfer the loads from the superstructure to the infrastructure
The use of flexible pile caps is not recommended, as there is a need to use transverse reinforcement to resist the tensile stresses caused by shear stresses
In all models the collapse occurred in the pile cap, that is, both the pillar and the metal post did not show signs of failure and, with the exception of the BEmb30sch model, all the pile caps presented ruin characterized by diagonal traction

Summary

INTRODUCTION

According to Xiao and Chen [5] and Velloso and Lopes [6], the use of metal piles provides some advantages in relation to concrete piles, such as the possibility of driving in soils that are difficult to transpose, high resistance to bending and traction, ease of cutting, splicing and transport. Even though they are widely used in bridges, viaducts, ports and containment structures, few studies on the use of metal piles in concrete blocks are found in the technical literature. The use of a steel plate on the top of the piles was made to analyze the hypothesis that this plate increases the area of the top of the pile, decreasing the tension in this region and, improving the structural behavior of the pile cap

CRITERIA USED FOR DESIGN

MECHANICAL AND GEOMETRIC PROPERTIES OF MODELS

CHARACTERIZATION OF MATERIALS AND EXPERIMENTAL TESTS

RESULTS AND DISCUSSIONS

CONCLUSIONS