• Title/Summary/Keyword: shear structure

Search Result 2,353, Processing Time 0.027 seconds

Nonlinear Seismic Response and Failure Behavior of reinforced Concrete Shear Wall Subjected to Base Acceleration (지반가속도에 의한 철근콘크리트 전단벽의 비선형 지진응답 및 파괴거동)

  • 유영화;신현목
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.3 no.3
    • /
    • pp.21-32
    • /
    • 1999
  • A ground motion resulting from the destructive earthquakes can subject reinforced concrete members to very large forces. The reinforced concrete shear walls are designed as earthquake-resistant members of building structure in order to prevent severe damage due to the ground motions. The current research activities on seismic behavior of reinforced concrete member under ground motions have been limited to the shaking table test or equivalent static cyclic test and the obtained results have been summarized and proposed for the seismic design retrofit of structural columns or shear walls. The present study predicted the seismic response and failure behavior of reinforced concrete shear wall subjected to base acceleration using the finite element method. A decrease in strength and stiffness, yielding of reinforcing bar, and repetition of crack closing and opening due to seismic load with cyclic nature are accompanied by the crack which is necessarily expected to take place in concrete member. In this study the nonlinear material models for concrete and reinforcing bar based on biaxial stress field and algorithm of dynamic analysis were combined to construct the analytical program using the finite element method. The analytical seismic response and failure behaviors of reinforced concrete shear wall subjected to several base accelerations were compared with reliable experimental result.

  • PDF

Performance-based Seismic Design of 9-Story Engineered Wood Office Building (9층 공학목재 사무소 건물의 성능기반 내진설계)

  • Chu, Yurim;Kim, Taewan;Kim, Seung Re
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.22 no.4
    • /
    • pp.225-233
    • /
    • 2018
  • One of engineered woods, glued laminated timber (GLT), can provide a constant level of performance and desired strength even if the quality of wood is low. Due to this fact, there is a growing interest in GLT using domestic species and related research has been carried out continuously. In addition, GLT is popularly being applied to the long-span or high-rise structures overseas. However, KBC 2016 does not allow the engineered woods to be used for middle and high-rise buildings by limiting height. Therefore, a proper design procedure and rationale should be clearly presented by the help of performance-based seismic design. With this background, the goal of this study is to establish a specific procedure for design of a 9-story building with RC shear walls and GLT frames according to the performance-based design of KBC 2016. The performance objectives were set according to KBC and the acceptance criteria for each goal were defined. The RC shear walls and GLT frames were designed by concrete and wood structure requirements, respectively. Analytical models were developed to reflect their nonlinear features, and both nonlinear static and dynamic analyses were conducted. Performance evaluation results showed that the shear walls have insufficient shear strength, so they were re-designed. Consequently, it has been confirmed that GLT frames can be applied to a 9-story office building with the assistance of RC shear walls and performance-based seismic design.

Stability Analysis of Shear-Flexible and Semi-Rigid Plane Frames (전단변형효과를 고려한 부분강절 평면뼈대구조의 안정성 해석)

  • Min, Byoung Cheol;Min, Dong Ju;Jung, Myung Rag;Kim, Moon Young
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.31 no.1A
    • /
    • pp.9-18
    • /
    • 2011
  • Generally the connection of structural members is assumed as hinge, rigid and semi-rigid connections. The exact tangent stiffness matrix of a semi-rigid frame element is newly derived using the stability functions considering shear deformations. Also, linearized elastic- and geometric-stiffness matrices of shear deformable semi-rigid frame are newly proposed. For the exact stiffness matrix, an accurate displacement field is introduced by equilibrium equation for beam-column under the bending and the axial forces. Also, stability functions considering sway deformation and force-displacement relations with elastic rotational spring on ends are defined. In order to illustrate the accuracy of this study, various numerical examples are presented and compared with other researcher's results. Lastly, shear deformation and semi-rigid effects on buckling behaviors of structure are parametrically investigated.

PIV Measurements of Flow Downstream of Polyurethane Heart Valve Prosthesis for Artificial Heart: Pulsatile Flow Experiment (PIV를 이용한 인공심장용 폴리우레탄 인공판막 하류의 유동 측정 : 맥동유동실험)

  • Yu, Jeong-Yeol;Kim, Jung-Gyeong;Seong, Jae-Yong;Jang, Jun-Geun;Min, Byeong-Gu
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.26 no.5
    • /
    • pp.629-639
    • /
    • 2002
  • In-vitro flow characteristics downstream of a polyurethane artificial heart valve and a Bjork-Shiley Monostrut mechanical valve have been comparatively investigated in pulsatile flow using particle image velocimetry (PIV). With a triggering system and a time-delayed circuit the velocity distributions on the two perpendicular measurement planes downstream of the valves are evaluated at any given instant in conjunction with the opening behaviors of valve leaflets during a cardiac cycle. The regions of stasis and high shear stress can be found simultaneously by examining the entire view of the instantaneous velocity and Reynolds shear stress fields. It is known that high shear stress regions exist at the interface between strong axial jet flows along the wall and vortical flows in the central area distal to the valves. In addition. there are large stagnation or recirculation regions in the vicinity of the valve leaflet, where thrombus formation can be induced by accumulation of blood elements damaged in the high shear stress zones. A correlation between the unsteady flow patterns downstream of the valve and the corresponding opening postures of the polyurethane valve membrane gives useful data necessary for improved design of the frame structure and leaflet geometry of the polyurethane valve.

A Coupled Analysis of Smart Plate Under Electro-Mechanical Loading Using Enhanced Lower-Order Shear Deformation Theory (개선된 저차 전단 변형 이론을 이용한 전기, 기계 하중을 받는 스마트 복합재 구조물의 연성 해석)

  • Oh, Jin-Ho;Cho, Maeng-Hyo;Kim, Jun-Sik
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.31 no.1 s.256
    • /
    • pp.121-128
    • /
    • 2007
  • Enhanced lower order shear deformation theory is developed in this study. Generally, lower order theories are not adequate to predict accurate deformation and stress distribution through the thickness of laminated plate. For the accurate prediction of detailed stress and deformation distributions through the thickness, higher order zigzag theories have been proposed. However, in most cases, simplified zigzag higher order theory requires $C_1$, shape functions in finite element implementation. In commercial FE softwares, $C_1$, shape functions are not so common in plate and shell analysis. Thus zigzag theories are useful for the highly accurate prediction of thick composite behaviors but they are not practical in the sense that they cannot be used conveniently in the commercial package. In practice, iso-parametric $C_0$ plate model is the standard model for the analysis and design of composite laminated plates and shells. Thus in the present study, an enhanced lower order shear deformation theory is developed. The proposed theory requires only $C_0$ shape function in FE implementation. The least-squared energy error between the lower order theory and higher order theory is minimized. An enhanced lower order shear deformation theory(ELSDT) in this paper is proposed for smart structure under complex loadings. The ELSDT is constructed by the strain energy transformation and fully coupled mechanical, electric loading cases are studied. In order to obtain accurate prediction, zigzag in-plane displacement and transverse normal deformation are considered in the deformation Held. In the electric behavior, open-circuit condition as well as closed-circuit condition is considered. Through the numerous examples, the accuracy and robustness of present theory are demonstrated.

Bonding strength of resin and porcelain depending on the effects of zirconia surface etching (지르코니아 표면 에칭처리 효과에 따른 레진 및 도재의 결합강도)

  • Park, Young-Dae;Han, Sok-Yoon
    • Journal of Technologic Dentistry
    • /
    • v.39 no.4
    • /
    • pp.243-251
    • /
    • 2017
  • Purpose: The purpose of this study was to investigate the effects of etching by monitoring the etched surfaces and the shear bonding strength of resin and porcelain with etched zirconia. Methods: The CAD/CAM was used to produce 24 zirconia blocks in groups of six. The zirconia specimen surfaces were sandblasted, and they were then divided into 12 specimens with surface etching and 12 specimens without etching for the control group. 12 specimens of composite resin were bonded using a curing light, and 12 specimens of porcelain underwent vita porcelain build-up sintering and the shear bonding strength was measured using a universal testing system. The SEM photographs were taken in order to observe any differences in the surfaces before and after etching, and they were magnified by a factor of 8 in order to observe fractured surface types. Results: The results of the shear bonding strength measurements are as follows: For the composite resin tests, between zirconia and resin, the shear bonding strength of the control group (NZR) without surface etching was 4.68 Mpa and the experimental group (EZC) with surface etching was 9.65 Mpa, which is significantly higher. The crystal structure of the zirconia was confirmed to be different in observations of the surfaces before and after etching. Conclusion : In comparing the shear bonding strength of zirconia and composite resin, the effects of etching were found to be significant. The effects of surface etching were also observed in fractured surfaces between zirconia and porcelain. This is expected to be applicable to various prosthetics as surface etching on zirconia is used in clinics.

Evaluation of Shear Elastic Modulus by Changing Injection Ratio of Grout (그라우트 주입률 변화에 따른 전단탄성계수 평가)

  • Baek, Seungcheol;Lee, Jundae;Ahn, Kwangkuk
    • Journal of the Korean GEO-environmental Society
    • /
    • v.14 no.2
    • /
    • pp.51-55
    • /
    • 2013
  • Among various construction methods, deep soil stabilization by chemical method have been widely used in order to improve soft ground. Dynamic variables using ground(such as sand, weathered granite soil and rock) -structure interaction design affected by dynamic load and cyclic load were studied a lot. However, there is something yet to learn about earthquake resistant design regarding reinforced ground by grout. Therefore, in this study using RC test, the correlation between shear strain and shear modulus with change of water content and injection rate in normal portland cement and clay was compared and analyzed by using Ramberg-Osgood model normalization As the result, dynamic coefficient was considerably affected by water content and grout injection rate.

Bending and Dynamic Characteristics of Antisymmetric Laminated Composite Plates considering a Simplified Higher-Order Shear Deformation (역대칭 복합적층판의 단순화된 고차전단변형을 고려한 휨과 동적 특성)

  • Han, Seong Cheon;Yoon, Seok Ho;Chang, Suk Yoon
    • Journal of Korean Society of Steel Construction
    • /
    • v.9 no.4 s.33
    • /
    • pp.601-609
    • /
    • 1997
  • Bending and vibration results for a laminated plate base on a simplified higher-order plate theory with four variables are presented. Assuming a constant in-plane rotation tensor through the thickness in Reddy's higher-order shear deformation theory it is shown that a simpler higher-order theory can be obtained with the reduction of one variable without significant loss in the accuracy. This simple higher-order shear deformation theory is then used for predicting the natural frequencies and deflection of simply-supported laminated composite plates. The results obtained for antisymmetrical laminated composite plates compare favorably with third-order and first-order shear deformation theory. The information presented should be useful to composite-structure designers, to researchers seeking to obtain better correlation between theory and experiment and to numerical analysts in checking out their programs.

  • PDF

Shear Behaviour of Sand-silt Mixture under Low and High Confining Pressures (모래-실트 혼합토의 구속압력에 따른 전단특성 파악)

  • Kim, Uk-Gie;Zhuang, Li
    • Journal of the Korean Geotechnical Society
    • /
    • v.31 no.3
    • /
    • pp.27-38
    • /
    • 2015
  • Triaxial tests on sand-silt mixture specimens under low and high confining pressures were performed to understand their shear behaviors. The fines content in the mixture is lower than the threshold value. A series of tests under different conditions including fines contents (0%, 9.8%, 14.7%, 19.6%), density of specimen (controlled by different compaction energies of $E_c=22kJ/m^3$, $E_c=504kJ/m^3$), confining pressure (100 kPa, 1 MPa, 3 MPa, 5 MPa) were performed to investigate influences of these factors. Based on the test results, the threshold fines content, where the dominant structure of mixture changes from sand-matrix to fines-matrix, decreases with the increase of confining pressure. Under very high confining pressures, as a result of sand particle crushing, the behavior of the dense specimen is similar to that of the loose specimen which shows hardening, compression behavior, and shear strength increases with increase of fines content. In conclusion, silt is granular material like sand, and its influence on shear behavior of sand-silt mixture is very different from that of plastic fines on sand-fines mixture.

Shear Strength and Failure Mode of Architectural Masonry Walls (내진보강된 치장조적벽의 파괴특성과 전단강도)

  • Jin, Hee-Yong;Han, Sang-Whan;Park, Young-Mi
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2008.04a
    • /
    • pp.89-92
    • /
    • 2008
  • This study investigates the shear behavior of architectural masonry veneer wall reinforced with specific reinforcement details proposed by this study. For this purpose, experimental tests were conducted using one un-reinforced masonry(URM) wall specimen and three reinforced masonry(RM) wall specimens under quasi static cyclic loads. Un-reinforced(plain) masonry wall is expressed that behavior and failure mode are different for aspect ratio(L/H) and axial compressive force. The test variables are wall aspect ratio and presence of reinforcement. These specimens are masonry structure for architectural clading that is not to exist the axial compressive force. thus the axial compressive force is excepted from test variable. Test result, Behavior of specimens are dominated over rocking mode, but final failure modes are combined with different behaviors. And FEMA273 has proposed the equation of shear strength of masonry pier subjected to in-plane loading. Shear strength equations are classified four types of failure mode that is Rocking, and Toe-Crushing, Bed-Joint-Sliding and Diagonal-Tension. FEMA273 equations predict the behavior modes well, but shear strength is shown in different result.

  • PDF