• Structural Engineering and Mechanics
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• v.41 no.4
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• pp.459-477
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• 2012

This paper attempts to determine the inclination of the compression strut within variable angle truss models for RC beams loaded in shear-flexure through a proposed semi-analytical approach. A truss unit is used to analyze a reinforced concrete beam, by the principle of virtual work under the truss analogy. The inclination of the compression strut is then theoretically derived. The concrete contribution is addressed by utilizing the compatibility condition within each truss unit. Comparisons are made between the predicted and published experimental results of the seventy one RC beams with respect to the shear strength and the inclined angle of the compression strut at this state to investigate the adequacy of the proposed semi-analytical approach.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.845-850
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• 2000

This paper presents the results of tests performed on the transfer girders which have been generally used between upper walls and lower frames in the hybrid structures. The 8 specimens were designed using (1) ACI method, (2) strut-tie model, and (3) X-type shear reinforcement cage. The capacities of the specimens are in general larger than the design values except the one designed according to strut-tie model. The reason for this difference seems to be due to the arbitrary allocation of transferred shear force to the path of direct compression strut and the path of indirect strut and tie. The failure modes turn out toe be (1) shear failure at critical shear zone, (2) compressive concrete crushing in the diagonal strut in the shear zone of transfer girder, and (3) compressive concrete crushing in the corner of upper wall.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.183-186
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• 2005

The Current design procedures of ACI 318-02 and CEB-FIP for the exterior beam-column joints do not provide engineers with a clear understanding of the physical behavior of the beam-column joints. In this paper, the failure strengths of the exterior beam-column joint specimens tested to failure were evaluated using the approach implementing 3-dimensional strut-tie models, design criteria of ACI 318-02, ACI-ASCE committee 352 and Park and paulay, and softened strut-tie model approach. The analysis results obtained from the 3-dimensional strut-tie models were compared with those obtained from the other approaches, and the validity of the approach implementing 3-dimensional strut-tie models were examined.

• Structural Engineering and Mechanics
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• v.81 no.2
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• pp.131-146
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• 2022

This study highlights the accuracy of several single strut models to predict the global response of infilled reinforced concrete (R/C) frames. To this aim, six experimental tests are selected to calibrate the numerical modeling. The width of the diagonal strut is calculated using several macro models from the literature. The mechanical properties of the diagonal strut are determined by using two methods: (a) by subtracting the bare frame response from that of the infilled frame, and (b) by calculating the axial strength in the diagonal direction. A combination between the different width and the axial force models is carried out to study the effects of each parameter on global response. Non-linear pushover analyses are conducted using SAP2000. The results indicate the accuracy of the macro-modeling approach to predict the behavior of the infilled frames.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.425-430
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• 2002

This thesis is a study on behavior for anchorage zone in prestressed double T beam using strut-tie model. Stress conditions of Anchorage zone in prestressed double T beam are very disturbed because large concentrated forces act on relatively small areas. Hence, anchorage zone must be considered in Design of prestressed double T beam. If irrational design or irrational construction be conducted, that may lose stability in capacity as structure. In current design practice, certain parts of structure are designed with extreme accuracy, while anchorage zone in prestressed double T beam is designed using common sense, and experience. Therefore, it is generally very conservative. For that reason, logical, reasonable concept and accuracies are desired at design of anchorage zone in prestressed double T beam. Strut-tie method satisfies those desires. In this thesis, anchorage zone in prestressed double T beam is analyzed by considering prestressing forces. Strut-tie model is constructed based on principle stress trajectory obtained from 3D-finite element analysis in anchorage zone, and amounts of reinforcement be obtained. Results of analysis are compared with the way used in current design practice, and this thesis presents that strut-tie model can be an economical design than current design methods without losing the degree of safety.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.109-110
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• 2018

Preloading Strut applied during installation of the wall jack, but additionally serves to minimize the displacement of soil pressure acting upon dissolution due to the difficulty. In this study, we developed an index of support for the release of stress to facilitate the dismantling of the strut uninstall. The refractive support the axial force acting on the strut are supportable, is refracted at minimum load, disassembly should be easy. In order to find the optimal shape and structural stability of the refractive support We have performed the numerical analysis and performance test to determine the final model. We carried out model tests and UTM test in order to understand the refractive performance and durability of the refractive support for optimal model. Results of the test UTM is refracted all shot 5 times within a target hit number, it was found that there is no problem of the refractive performance. Further, the results of model experiments, it was found that to ensure sufficient durability more than the performance target value of the pin joint support structure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1065-1079
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• 2014

The ultimate behavior of reinforced concrete corbel is complicated due to the primary design variables including the shear span-to-effective depth ratio a/d, flexural reinforcement ratio, load condition, and material properties. In this study, a simple indeterminate strut-tie model reflecting all characteristics of the ultimate strength and complicated structural behavior is proposed for the design of the reinforced concrete corbels with shear span-to-effective depth ratio of $a/d{\leq}1$. A load distribution ratio, defined as the fraction of applied load transferred by horizontal truss mechanism, is also proposed to help structural designers perform the design of reinforced concrete corbels by using the strut-tie model approaches of current design codes. For the development of the load distribution ratio, numerous material nonlinear finite element analyses of the proposed indeterminate strut-tie model were conducted by changing primary design variables. The ultimate strengths of reinforced concrete corbels tested to failure were evaluated by incorporating the proposed strut-tie model and load distribution ratio into the ACI 318-11's strut-tie model method. The validity of the proposed model and load distribution ratio was examined by comparing the strength analysis results with those by the ACI 318-11's conventional design method and strut-tie model methods of current design codes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.2
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• pp.425-436
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• 2014

Although the strut-tie model approaches of current design codes are regarded as the valuable methods for designs of structural concretes with D-regions, the approaches have to be improved because of the uncertainties in terms of the concepts and provisions for designs of 3-dimensional structural concretes. To improve the uncertainties, a new strut-tie model approach is proposed in this study. In the proposed approach, the concepts of employing a 3-dimensional grid element allowing load transfers in all directions at a node to construct a strut-tie model, a numerical analysis approach to determine the effective strengths of concrete struts and nodal zones by reflecting the effects of reinforcing bars and 3-dimensional stress state, and maximum areas of struts and ties to examine their load carrying capacities are integrated into the strut-tie model approaches of current design codes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.3
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• pp.531-539
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• 2017

The strut-tie model approach has been recognized as an efficient methodology for the design of all types of concrete members with D-regions, and the approach has been accepted in design codes globally. However, the design of concrete members with the approach requires many iterative numerical structural analyses, numerous graphical calculations, enormous times and efforts, and designer's subjective decisions in terms of the development of appropriate strut-tie model, determination of required areas of struts and ties, and verification of strength conditions of struts and nodal zones. In this study, a computer graphics program, that enables the design of concrete members efficiently and professionally by overcoming the forementioned limitations of the strut-tie model approach, is developed. In the computer graphics program, the numerical programs that are essential in the strut-tie model analysis and design of concrete members including finite element analysis programs for the plane truss and solid problems with all kinds of boundary conditions, a program for automatic determination of effective strengths of struts and nodal zones, and a program for graphical verification of developed strut-tie model's appropriateness by displaying various geometrical shapes of struts and nodal zones, are loaded. Great efficiency and convenience during the application of the strut-tie model approach may be provided by the various graphics environment-based functions of the proposed program.

• Journal of the Korea Concrete Institute
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• v.23 no.1
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• pp.13-22
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• 2011

In this study, ultimate strengths of 51 continuous reinforced concrete deep beams were evaluated by the ACI 318M-08's strut-tie model approach implemented with the presented indeterminate strut-tie model and load distribution ratio of the companion paper. The ultimate strengths of the continuous deep beams were also estimated by the shear equations derived based on experimental results, conventional design codes based on experimental and theoretical shear strength models, and current strut-tie model design codes. The validity of the presented strut-tie model and load distribution ratio was examined through the comparison of the strength analysis results classified according to the primary design variables of shear span-to-effective depth ratio, flexural reinforcement ratio, and concrete compressive strength. The present study results of ultimate strengths obtained using the indeterminate strut-tie model and load distribution ratio of the continuous deep beams agree fairly well with those obtained using other approaches. In addition, the present approach reflected the effect of the primary design variables on the ultimate strengths of the continuous deep beams consistently and accurately. Therefore, the present study will help structural designers to conduct rational and practical strut-tie model designs of continuous deep beams.