• 제목/요약/키워드: shear design

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Evaluation and Improvement of Deformation Capacities of Shear Walls Using Displacement-Based Seismic Design

  • Oh, Young-Hun;Han, Sang-Whan;Choi, Yeoh-Soo
    • International Journal of Concrete Structures and Materials
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    • 제18권1E호
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    • pp.55-61
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    • 2006
  • RC shear walls are frequently used as lateral force-resisting system in building construction because they have sufficient stiffness and strength against damage and collapse. If RC shear walls are properly designed and proportioned, these walls can also behave as ductile flexural members like cantilevered beams. To achieve this goal, the designer should provide adequate strength and deformation capacity of shear walls corresponding to the anticipated deformation level. In this study, the level of demands for deformation of shear walls was investigated using a displacement-based design approach. Also, deformation capacities of shear walls are evaluated through laboratory tests of shear walls with specific transverse confinement widely used in Korea. Four full-scale wall specimens with different wall boundary details and cross-sections were constructed for the experiment. The displacement-based design approach could be used to determine the deformation demands and capacities depending on the aspect ratio, ratio of wall area to floor plan area, flexural reinforcement ratio, and axial load ratio. Also, the specific boundary detailing for shear wall can be applied to enhance the deformation capacity of the shear wall.

압전 수정진동자의 설계민감도 해석과 위상 최적설계 (Design Sensitivity Analysis and Topology Optimization of Piezoelectric Crystal Resonators)

  • 하윤도;조선호;정상섭
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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    • pp.335-342
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    • 2005
  • Using higher order Mindlin plates and piezoelectric materials, eigenvalue problems are considered. Since piezoelectric crystal resonators produce a proper amount of electric signal for a thickness-shear frequency, the objective is to decouple the thickness-shear mode from the others. Design variables are the bulk material densities corresponding to the mass of masking plates for electrodes. The design sensitivity expressions for the thickness-shear frequency and mode shape vector are derived using direct differentiation method(DDM). Using the developed design sensitivity analysis (DSA) method, we formulate a topology optimization problem whose objective function is to maximize the thickness-shear component of strain energy density at the thickness-shear mode. Constraints are the allowable volume and area of masking plate. Numerical examples show that the optimal design yields an improved mode shape and thickness-shear energy.

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Design Equation for Punching Shear Capacity of SFRC Slabs

  • Higashiyama, Hiroshi;Ota, Akari;Mizukoshi, Mutsumi
    • International Journal of Concrete Structures and Materials
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    • 제5권1호
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    • pp.35-42
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    • 2011
  • In this paper, a design equation for the punching shear capacity of steel fiber reinforced concrete (SFRC) slabs is proposed based on the Japan Society of Civil Engineers (JSCE) standard specifications. Addition of steel fibers into concrete improves mechanical behavior, ductility, and fatigue strength of concrete. Previous studies have demonstrated the effectiveness of fiber reinforcement in improving the shear behavior of reinforced concrete slabs. In this study, twelve SFRC slabs using hooked-ends type steel fibers are tested with varying fiber dosage, slab thickness, steel reinforcement ratio, and compressive strength. Furthermore, test data conducted by earlier researchers are involved to verify the proposed design equation. The proposed design equation addresses the fiber pull-out strength and the critical shear perimeter changed by the fiber factor. Consequently, it is confirmed that the proposed design equation can predict the punching shear capacity of SFRC slabs with an applicable accuracy.

A Study on Optimum Distribution of Story Shear Force Coefficient for Seismic Design of Multi-story Structure

  • Oh, Sang Hoon;Jeon, Jongsoo
    • 국제초고층학회논문집
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    • 제3권2호
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    • pp.121-145
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    • 2014
  • The story shear force distributions of most seismic design codes generally reflect the influences of higher vibration modes based on the elastic deformations of structures. However, as the seismic design allows for the plastic behavior of a structure, the story shear force distribution shall be effective after it is yielded due to earthquake excitation. Hence this study conducted numerical analyses on the story shear force distributions of most seismic design codes to find out the characteristics of how a structure is damaged between stories. Analysis results show that the more forces are distributed onto high stories, the lower its concentration is and the more energy is absorbed. From the results, this study proposes the optimum story shear force distribution and its calculation formula that make the damages uniformly distributed onto whole stories. Consequently, the story damage distribution from the optimum calculation formula was considerably more stable than existing seismic design codes.

Effect of plate properties on shear strength of bolt group in single plate connection

  • Ashakul, Aphinat;Khampa, Kriangkrai
    • Steel and Composite Structures
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    • 제16권6호
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    • pp.611-637
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    • 2014
  • A single plate shear connection, or shear tab, is a very popular shear connection due to its merit in ease of construction and material economy. However, problems in understanding the connection behavior, both in terms of strength and ductility, have been well-documented. Suggestions or design model for single plate connections in AISC Design Manual have been altered several times, with the latest edition settling down to giving designers pre-calculated design strength tables if the connection details agree with given configurations. Results from many full-scale tests and finite element models in the past suggest that shear strength of a bolt group in single plate shear connections might be affected by yield strength of plate material; therefore, this research was aimed to investigate and clarify effects of plate yield strength and thickness on shear strength of the bolt group in the connections, including the validity of using a plate thickness/bolt diameter ratio ($t_p/d_b$) in design, by using finite element models. More than 20 models have been created by using ABAQUS program with 19.0- and 22.2-mm A325N bolts and A36 and Gr.50 plates with various thicknesses. Results demonstrated that increase of plate thickness or plate yield strength, with the $t_p/d_b$ ratio remained intact, could significantly reduce shear strength of the bolt group in the connection as much as 15 percent. Results also confirmed that the $t_p/d_b$ ratio is a valid indicator to be used for guaranteeing strength sufficiency. Because the actual ratio recommended by AISC Design Manual is $t_p/d_b$ + 1.6 (mm) for connections with a number of bolts less than six and plate yield strength in construction is normally higher than the nominal value used in design, it is proposed that shear strength of a bolt group in single plate connections with a number of bolts equal or greater than seven be reduced by 15 percent and the $t_p/d_b$ ratio be limited to 0.500.

Direct design of partially prestressed concrete solid beams

  • Alnuaimi, A.S.
    • Structural Engineering and Mechanics
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    • 제27권6호
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    • pp.741-771
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    • 2007
  • Tests were conducted on two partially pre-stressed concrete solid beams subjected to combined loading of bending, shear and torsion. The beams were designed using the Direct Design Method which is based on the Lower Bound Theorem of the Theory of Plasticity. Both beams were of $300{\times}300mm$ cross-section and 3.8 m length. The two main variables studied were the ratio of the maximum shear stress due to the twisting moment, to the shear stress arising from the shear force, which was varied between 0.69 and 3.04, and the ratio of the maximum twisting moment to the maximum bending moment which was varied between 0.26 and 1.19. The required reinforcement from the Direct Design Method was compared with requirements from the ACI and the BSI codes. It was found that, in the case of bending dominance, the required longitudinal reinforcements from all methods were close to each other while the BSI required much larger transverse reinforcement. In the case of torsion dominance, the BSI method required much larger longitudinal and transverse reinforcement than the both the ACI and the DDM methods. The difference in the transverse reinforcement is more pronounce. Experimental investigation showed good agreement between design and experimental failure loads of the beams designed using the Direct Design Method. Both beams failed within an acceptable range of the design loads and underwent ductile behaviour up to failure. The results indicate that the Direct Design Method can be successfully used to design partially prestressed concrete solid beams which cater for the combined effect of bending, shear and torsion loads.

Numerical simulation of Y-type perfobond rib shear connectors using finite element analysis

  • Kim, Kun-Soo;Han, Oneil;Gombosuren, Munkhtulga;Kim, Sang-Hyo
    • Steel and Composite Structures
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    • 제31권1호
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    • pp.53-67
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    • 2019
  • This study presents finite element analysis (FEA) on a Y-type perfobond rib shear connection using Abaqus software. The performance of a shear connection is evaluated by conducting a push-out test. However, in practice, it is inefficient to verify the performance by conducting a push-out test with regard to all design variables pertaining to a shear connector. To overcome this problem, FEA is conducted on various shear connectors to accurately estimate the shear strength of the Y-type perfobond rib shear connection. Previous push-out test results for 14 typical push-out test specimens and those obtained through FEA are compared to analyze the shear behavior including consideration of the design variables. The results show that the developed finite element model successfully reflects the effects of changes in the design variables. In addition, using the developed FEA model, the shear resistance of a stubby Y-type perfobond rib shear connector is evaluated based on the concrete strength and transverse rebar size variables. Then, the existing shear resistance formula is upgraded based on the FEA results.

Reinforced concrete corbels strengthened with carbon fiber reinforced plastics

  • Lu, Wen-Yao;Yu, Hsin-Wan;Chen, Chun-Liang;Yang, Tzong-Hwan;Lin, Yu-Sin
    • Computers and Concrete
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    • 제10권3호
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    • pp.259-276
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    • 2012
  • A total of nine reinforced concrete corbels were tested, in this study. Six were externally strengthened with carbon fiber reinforced plastics (CFRP), in the horizontal direction. The cross-sectional area of CFRP and the shear span-to-effective depth ratios are the parameters considered, in this study. Test results indicate that the higher the cross-sectional area of CFRP, the higher is the shear strength of the corbels, and the lower the shear span-to-effective depth ratios, the higher is the shear strength of corbels. The shear strength predicted by the design provisions in section 11.8 of the ACI Code, the strut-and-tie model in Appendix A of the ACI Code, and the softened strut-and-tie (SST) model were compared with the test results. The comparisons show that both the strut-and-tie model in Appendix A of the ACI Code, and the SST model can accurately predict the shear strength of reinforced concrete corbels, strengthened with CFRP.

지반주기를 고려한 다층지반의 평균전단파속도 추정 방법 평가 (Evaluation of Average Shear-wave Velocity Estimation Methods of Multi-layered Strata Considering Site Period)

  • 김동관
    • 한국지진공학회논문집
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    • 제23권3호
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    • pp.191-199
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    • 2019
  • To calculate proper seismic design load and seismic design category, the exact site class for construction site is required. At present, the average shear-wave velocity for multi-layer soil deposits is calculated by the sum of shear-wave velocities without considering of vertical relationship of the strata. In this study, the transfer function for the multi-layered soil deposits was reviewed on the basis of the wave propagation theory. Also, the transfer function was accurately verified by the finite element model and the eigenvalue analysis. Three methods for site period estimation were evaluated. The sum of shear-wave velocities underestimated the average shear-wave velocities of 526 strata with large deviations. The equation of Mexican code overestimated the average shear-wave velocities. The equation of Japanese code well estimated the average shear-wave velocities with small deviation.

Tests of reinforced concrete deep beams

  • Lu, Wen-Yao;Hsiao, Hsin-Tai;Chen, Chun-Liang;Huang, Shu-Min;Lin, Ming-Che
    • Computers and Concrete
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    • 제15권3호
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    • pp.357-372
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    • 2015
  • This study reports the test results of twelve reinforced concrete deep beams. The deep beams were tested with loads applied through and supported by columns. The main variables studied were the shear span-to-depth ratios, and the horizontal and vertical stirrups. The shear strengths can be effectively enhanced for deep beams reinforced with both horizontal and vertical stirrups. The test results indicate the shear strengths of deep beams increase with the decrease of the shear span-to-depth ratios. The normalized shear strengths of the deep beams did not increase proportionally with an increase in effective depth. An analytical method for predicting the shear strengths of deep beams is proposed in this study. The shear strengths predicted by the proposed method and the strut-and-tie model of the ACI Code are compared with available test results. The comparison shows the proposed method can predict the shear strengths of reinforced concrete deep beams more accurately than the strut-and-tie model of the ACI Code.