Strength predictions of pile caps by a strut-and-tie model approach

2008 ◽  
Vol 35 (12) ◽  
pp. 1399-1413 ◽  
Author(s):  
JungWoong Park ◽  
Daniel Kuchma ◽  
Rafael Souza
Keyword(s):  
Reinforced Concrete ◽  
American Concrete Institute ◽  
Valuable Insight ◽  
Strain Compatibility ◽  
Strut And Tie ◽  
Pile Cap ◽  
Pile Caps ◽  
Strut And Tie Model ◽  
And Behavior ◽  
Model Approach

In this paper, a strut-and-tie model approach is presented for calculating the strength of reinforced concrete pile caps. The proposed method employs constitutive laws for cracked reinforced concrete and considers strain compatibility. This method is used to calculate the load-carrying capacity of 116 pile caps that have been tested to failure in structural research laboratories. This method is illustrated to provide more accurate estimates of behavior and capacity than the special provisions for slabs and footings of the 1999 American Concrete Institute (ACI) code, the pile cap provisions in the 2002 CRSI design handbook, and the strut-and-tie model provisions in either the 2005 ACI code or the 2004 Canadian Standards Association (CSA) A23.3 standard. The comparison shows that the proposed method consistently well predicts the strengths of pile caps with shear span-to-depth ratios ranging from 0.49 to 1.8 and concrete strengths less than 41 MPa. The proposed approach provides valuable insight into the design and behavior of pile caps.

An evaluation of pile cap design methods in accordance with the Canadian design standard

2004 ◽  
Vol 31 (1) ◽  
pp. 109-119 ◽  
Author(s):  
William Cavers ◽  
Gordon A Fenton
Keyword(s):  
Reinforced Concrete ◽  
Structural Design ◽  
Design Methods ◽  
Building Codes ◽  
Design Models ◽  
Design Standard ◽  
Strut And Tie ◽  
Pile Cap ◽  
Pile Caps ◽  
Strut And Tie Model

There are a number of design methods that have been described for the design of pile caps, but there has been no consensus on which method provides the best approach for the working designer. This paper describes a study conducted to establish the performance of several pile cap design methods, particularly with respect to the Canadian standard, CSA A23.3-94. Previous research was examined to determine the basis of the design methods and the state of current research. The design methods identified were then applied to pile caps for which test data were available. The theoretical loads obtained using the various design methods were compared with the experimental loads. The results of this study indicate that two design models of the five examined are the most suitable. This study also indicates that the provisions of the Canadian design standard are adequate. A possible refinement of the strut-and-tie model incorporating a geometric limit is also outlined.Key words: building codes, footings, pile caps, reinforced concrete, structural design.

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

2020 ◽  
Vol 13 (6) ◽  
Author(s):  
Rodrigo Gustavo Delalibera ◽  
Marco Aurélio Tomaz ◽  
Vitor Freitas Gonçalves ◽  
José Samuel Giongo
Keyword(s):  
Reinforced Concrete ◽  
Structural Behavior ◽  
Concrete Piles ◽  
Strut And Tie ◽  
Concrete Pile ◽  
Steel Piles ◽  
Pile Cap ◽  
Pile Caps ◽  
Embedment Length ◽  
Strut And Tie Model

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.

Experimental Study on Deep Four-Pile Caps with Different Reinforcement Layouts Based on 3D Strut-and-Tie Analogy

2008 ◽  
Vol 400-402 ◽  
pp. 917-922 ◽  
Author(s):  
Qian Gu ◽  
Cheng Fang Sun ◽  
Shao Min Peng
Keyword(s):  
Load Capacity ◽  
Longitudinal Reinforcement ◽  
Test Results ◽  
Test Procedures ◽  
Strut And Tie ◽  
Pile Cap ◽  
Scale Ratio ◽  
Pile Caps ◽  
Strut And Tie Model ◽  
Distributed Reinforcement

Based on 3D strut-and-tie analogy developed for analyzing the load-transferring mechanism of deep pile cap, this paper focuses on the effect of different longitudinal reinforcement layouts at the lower part of cap on the mechanical behaviors of deep four-pile cap. Besides a common layout of uniformly distributed reinforcement by the flexural theory, three different layouts of concentrated reinforcement over piles were designed by 3D strut-and-tie analogy. All specimens were limited in same reinforcement percentages, dimensions, materials and test procedures. Four specimens with the scale ratio of 1/5 were tested under the statically incremental gravity loading. The load capacity, deflection, strain of longitudinal reinforcement of specimens were measured, and the failure mode, crack propagation, deformation of specimens and stress distribution of reinforcement were analyzed. Through comparisons of the test results among all specimens, it was found that deep pile cap failed in shear and corner-pile punching whether with concentrated or uniform reinforcement, and the reinforcement concentrated over each two adjacent piles, similar to the tension bars in the strut-and-tie model, had considerable advantages than common uniform reinforcement layout. The ultimate strength of deep pile cap with concentrated reinforcement was significantly increased, while the improvement of deformation resistance and brittleness of deep pile cap was limited. According to above findings, the appropriate reinforcement layouts for deep pile cap were suggested in this paper.

scholarly journals Enhanced strut-and-tie model for reinforced concrete pile caps

2017 ◽  
Author(s):  
Alexandre Mathern ◽  
Gautier Chantelot ◽  
Per-Ola Svahn ◽  
Per Kettil ◽  
Rasmus Rempling ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Strut And Tie ◽  
Concrete Pile ◽  
Pile Caps ◽  
Strut And Tie Model

ANÁLISE NUMÉRICA DE BLOCO SOBRE DUAS ESTACAS METÁLICAS

2020 ◽  
Vol 16 (1) ◽  
pp. 91-104
Author(s):  
Rodrigo Gustavo Delalibera ◽  
Vítor Freitas Gonçalvez
Keyword(s):  
Numerical Models ◽  
Structural Behavior ◽  
The Finite Element Method ◽  
Good Match ◽  
Strut And Tie ◽  
Steel Piles ◽  
Pile Cap ◽  
Pile Caps ◽  
Strut And Tie Model ◽  
Made In

RESUMO:  Perfis metálicos são utilizadas em diversas aplicações na construção civil. No entanto, ainda existem dúvidas quanto ao comportamento estrutural de blocos de coroamento quando se utiliza estacas metálicas. No presente trabalho foram desenvolvidos modelos numéricos, por meio do método dos elementos finitos, de um bloco sobre duas estacas metálicas, com o intuito de identificar tendências com relação ao comportamento estrutural bloco. Os resultados numéricos apresentaram correlações satisfatórias com os resultados experimentais, com os quais foram feitas análises comparativas. Concluiu-se que o modelo de bielas e tirantes utilizado no dimensionamento do bloco sobre estacas analisado não apresentou resultado esperado para o comportamento estrutural de blocos sobre estacas metálicas e, portanto, mais estudos devem ser realizados para se obter um modelo analítico satisfatório. ABSTRACT: Steel piles are used on various fields on civil construction. However, there are still some uncertainties about the structural behavior of pile caps supported on steel piles. On this study the finite element method was used to develop numerical models of a two-pile cap on steel pile, with the aim of identifying tendencies on the structural behavior of the element. The numerical results showed good match with the experimental results of Tomaz (2018), which were used for analysis. It was concluded that the strut and tie model proposed by Blévot & Frémy (1967), usually used on the design of pile caps, doesn’t depict the actual structural behavior of pile caps on steel piles and, therefore, further studies must be made in order to develop a better physical model.

scholarly journals Variation analysis effects of square and rectangular columns section with different longitudinal reinforcement rates in the main reinforcement two pile caps analysis

2017 ◽  
Vol 10 (3) ◽  
pp. 760-787 ◽  
Author(s):  
F. S. MUNHOZ ◽  
J.S. GIONGO
Keyword(s):  
Experimental Program ◽  
Longitudinal Reinforcement ◽  
Structural Elements ◽  
Rectangular Section ◽  
Central Section ◽  
Strut And Tie ◽  
Pile Cap ◽  
Pile Caps ◽  
Strut And Tie Model ◽  
Rectangular Columns

ABSTRACT The transition between the columns of building and foundation had been used the pile-cap structural elements. The most appropriate method for the pile caps design is the Strut and Tie model. In most cases in the structural project is not considered the influence of certain parameters: the columns cross section and the amount of longitudinal reinforcement columns. This paper studies the effect of the variability of the geometric section of square and rectangular columns, with different longitudinal reinforcement rates, in the main reinforcement traction two pile caps. The basis for study was development experimental program in the Structures Laboratory of EESC-USP . The traction reinforcement bars strains are reduced the pile-caps central section to pile-caps sections that approximate cutting axis shows the experimental results. In models with columns of elongated rectangular section and with great reinforcement rates this reduction is smaller.

Failure Probabilities of Reinforced Concrete Square Pile Caps

2007 ◽  
Vol 23 (2) ◽  
pp. 173-180
Author(s):  
W.-Y. Lu
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Design Method ◽  
Main Body ◽  
Concrete Pile ◽  
Diagonal Compression ◽  
Pile Cap ◽  
Pile Caps ◽  
Strut And Tie Model ◽  
Failure Probabilities

AbstractAn analytical model for determining the shear strength of concrete pile caps under the failure mode of diagonal-compression originally based on the softened strut-and-tie model is proposed. The failure probabilities of reinforced concrete pile caps are investigated by Monte Carlo method. The results indicate that the proposed model can accurately predict the shear strength of the pile caps. The distribution of the failure probabilities for pile caps designed to ACI 318-02 Appendix A and the proposed design method are more uniform than that designed to the ACI 318-99. The ACI 318-99 is very conservative and cannot provide a consistent safety for pile caps design. It is suggested that the procedures in the ACI 318-02 Appendix A should be moved to the main body of ACI 318-02 and the proposed design method should be incorporated into the current reinforced concrete pile cap design methods.

scholarly journals Design of deep pile caps by strut-and-tie models

2019 ◽  
Vol 12 (4) ◽  
pp. 832-857
Author(s):  
D. M. SANTOS ◽  
M. L. CARVALHO ◽  
F. R. STUCCHI
Keyword(s):  
Bearing Capacity ◽  
Classical Method ◽  
Concrete Structures ◽  
Experimental Tests ◽  
Strut And Tie ◽  
Pile Cap ◽  
Pile Caps ◽  
Strut And Tie Model

Abstract There are many methods for designing pile caps, but there is still no consensus on which one provides the best approach for the practical engineers. In Brazil, many structural designers use the classical Blévot method; however, the applicability of the method has been questioned after the revision of the NBR 6118 standard for design of concrete structures in 2014. To support structural designers, a strut-and-tie model has recently been developed that relates the classical method to the most current concepts of strut-and-tie models. The theoretical bearing capacity of four-pile cap obtained through several strut-and-tie models are compared with experimental tests. The results show that this recently developed model is suitable for the design of deep pile cap.

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