Three-Dimensional Grid Strut-and-Tie Model Approach in Structural Concrete Design

Yun, Young Mook; Kim, Byunghun; Ramírez, Julio A.

doi:10.14359/51700791

Cited by 8 publications

(7 citation statements)

References 9 publications

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“…Third, since the nodal zone effective strengths in present codes and specifications have been validated with 2D models, effective strengths of nodal zones for 3D strut-and-tie models were developed for the proposed method. Effective stresses for the 3D nodal zones shaped by concrete struts and bearing plates are developed employing concepts introduced in the 3D grid STM method of Yun et al (2018). The effective strength of the nodal zone confined by compressive members is determined taking into account the effects of 3D state of stress and the degree of confinement.…”

Section: Refined 3d Stm Methods Of Present Studymentioning

confidence: 99%

A Three-Dimensional Strut-and-Tie Model for a Four-Pile Reinforced Concrete Cap

Yun

Chae²,

Ramírez

2019

ACT

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Reinforced concrete pile caps have been traditionally designed with sectional methods in codes and specifications. Since the 1990s, the two-dimensional strut-and-tie model (2D STM) methods, introduced in codes and specifications (Ref. ACI 318-14 and the 8 th Edition of the AASHTO LRFD Specifications), have become the design method of choice for pile cap designs. However, sectional methods and 2D STM provisions in current design codes have serious limitations when applied to the design of members with behavior more appropriately captured using three-dimensional (3D) approaches. In this paper, a refined 3D STM method for analysis and design of pile caps is illustrated. In the proposed method, a statically indeterminate 3D STM with diagonal ties is employed to account for the load-carrying capacity in tension of some regions in four-pile caps. The effective strengths of 3D concrete struts and nodal zones are determined by reflecting the effects of the 3D stress states and the degree of concrete confinement provided by reinforcement. The load-carrying capacities of struts and ties are determined using an iterative technique with the axial stresses of concrete struts equal to effective strengths. An extensive comparison between current and proposed methods is conducted using experimental data from 115 reinforced concrete pile caps tested to failure. Besides, several pile caps are designed using the current and proposed methods, and a comparison of the results from the design is conducted.

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Section: Refined 3d Stm Methods Of Present Studymentioning

confidence: 99%

A Three-Dimensional Strut-and-Tie Model for a Four-Pile Reinforced Concrete Cap

Yun

Chae²,

Ramírez

2019

ACT

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“…Multiple books including Collins and Mitchell (2001), Wight et al (2011), and Nawy et al (2011) have introduced a determinate STM representing an arch load transfer mechanism, shown in Figure 1(a), in which an external load is directly transferred to a column by an inclined concrete strut. Yun and Ramirez (1994) and KCI (2013) introduced a determinate STM representing a horizontal truss mechanism, shown in Figure 1(b), in which an external load is transferred to the column by the combination of inclined concrete struts and a horizontal steel tie. In this study, a first-order statically indeterminate STM for reinforced concrete corbels with a shear span-to-effective depth ratio of less than 1.0 is proposed.…”

Section: Proposal Of Stm and Load Distribution Ratiomentioning

confidence: 99%

An optimum indeterminate strut-and-tie model for reinforced concrete corbels

Yun

Chae²

2019

Advances in Structural Engineering

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The failure behavior of a reinforced concrete corbel is complicated due to the shear span-to-effective depth ratio, reinforcement patterns, load conditions, and material properties. In this study, an optimum first-order indeterminate strut-and-tie model that reflects all characteristics of the failure behavior is proposed for the rational design of reinforced concrete corbels with a shear span-to-effective depth ratio of less than 1.0. A load distribution ratio that transforms the indeterminate strut-and-tie model into a determinate model is also developed to help structural designers design reinforced concrete corbels using the strut-and-tie model methods of current design codes. For the development of the load distribution ratio, a material nonlinear finite element analysis of the proposed first-order indeterminate strut-and-tie model was conducted repeatedly by changing the combination of primary design variables of the corbels. To examine the validity of our results, the ultimate strengths of 294 reinforced concrete corbels tested to failure by other investigators were predicted using the proposed strut-and-tie model with the load distribution ratio, the existing determinate strut-and-tie models representing arch and truss load transfer mechanisms, and the American Concrete Institute 318 conventional design method based on a shear friction theory. The ultimate strengths predicted by the proposed strut-and-tie model agreed fairly well with the experimental results. The ratio of the experimental strength to the predicted strength (and coefficient of variation) was 1.09 (28.0%), implying that the proposed strut-and-tie model can represent the load transfer mechanisms of corbels most appropriately.

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“…Similarly, based on the ESO TO methods, He and Liu (2010) generated STM models for anchorage diaphragms, Shobeiri and Ahmadi‐Nedushan (2017) applied a bidirectional ESO method to obtain optimized material distributions for several 3D D‐regions, and Zhong, Wang, Zhou, and Li (2017) used a microtruss‐based ESO method for 3D STM models. Yun, Kim, and Ramirez (2018) generated 3D STM models using a grid‐based approach. Dey and Karthik (2019) analyzed several pile‐cap designs based on 3D compatible STM models.…”

Section: Introductionmentioning

confidence: 99%

Optimization‐based three‐dimensional strut‐and‐tie model generation for reinforced concrete

Xia

Langelaar

Hendriks

2020

Computer aided Civil Eng

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Strut-and-tie modelling (STM) is an effective and widely used method to design disturbed regions (D-regions) of reinforced concrete structures. Among the various steps of STM, finding a suitable truss-analogy model is the most challenging part. Even for experienced engineers it is difficult to find representative models for complex D-regions, and this task is even harder for three-dimensional (3D) Dregions. To date, only a few 3D STM models have been proposed by researchers for several complex D-regions, which leaves practitioners with little guidance.In order to solve this problem, a method is proposed to automatically generate 3D optimization-based STM (3D-OPT-STM) models. The generation method comprises a compliance-based topology optimization process that generates optimized structural forms by maximizing stiffness, a topology extraction method, and a shape optimization method. In this study, three 3D-OPT-STM models are generated for typical 3D D-regions, and their performances are compared to manually created STM models. The generated 3D-OPT-STM models result in more economical designs. Moreover, geometrical and loading parameter studies demonstrate the applicability and robustness of the proposed method.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Three-Dimensional Grid Strut-and-Tie Model Approach in Structural Concrete Design

Cited by 8 publications

References 9 publications

A Three-Dimensional Strut-and-Tie Model for a Four-Pile Reinforced Concrete Cap

A Three-Dimensional Strut-and-Tie Model for a Four-Pile Reinforced Concrete Cap

An optimum indeterminate strut-and-tie model for reinforced concrete corbels

Optimization‐based three‐dimensional strut‐and‐tie model generation for reinforced concrete

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