Design of Rigid Pile Caps through an Iterative Strut-and-Tie Model

Abstract

The aim of this work is to present a strut-and-tie model for design of reinforced concrete pile caps. The model considers both failure by crushing of the compressed struts and by yielding of the tie reinforcement. Unlike some traditional models, crushing of the compressed concrete is not checked at the section in direct contact with the column base (column/pile cap interface). In this work, crushing of concrete is verified in a section at a certain depth inside the pile cap. Thus, this verification is replaced by determining the height of the nodal zone at the top of the pile cap required not to cause crushing of the struts. An iterative algorithm is used for this purpose. Comparison with a large number of experimental results available in the literature demonstrates the effectiveness of the proposed model for the design of concrete pile caps. Numerical examples of practical use of the model are also presented.

Reliability Analysis Of Rigid Pile Caps Using An Iterative Strut-And-Tie Model

“…Table 3 shows the results of the iterative process to find x, using equations ( 2) and (5). 3 is practically the same as that obtained in [11]. The advantage of the present formulation is the possibility of drawing graphs as shown in Figs.…”

“…The determination of the depth of this horizontal plane (the height of the CCC nodal zone under the column) requires an iterative process. In a previous article [11], the magnified area under the column was defined considering a load distribution along the height of the pile-cap with the same inclination of the struts. The present paper introduces a modification in the geometry of the magnified area that simplifies the use of the model.…”

“…In the previous paper [11], the magnified area under the column was defined considering a load distribution along the height of the pile-cap with the same inclination of the struts. In this work, the load distribution is considered as shown in Fig.…”

“…In order to avoid crushing of the struts it is necessary to limit σ c2 f cd2 . Here there is no consensus about the limit to the compressive stress f cd2 , as shown in [11]. So, conservatively, it is adopted according to CEB-FIP Model Code [13] recommendations.…”

“…In these methods, the value of x is chosen without any rational criterion. In a previous paper, the author [11] presented a strutand-tie model for design of rigid pile caps based on the concept of magnified area under the column. In this magnified area, compressive stresses have been reduced enough not to cause crushing of the struts.…”