• Title/Summary/Keyword: punching shear

Search Result 214, Processing Time 0.038 seconds

A Study on the Modified Simple Truss Model to Predict the Punching Shear Strength of PSC Deck Slabs (PSC 바닥판의 뚫림전단강도 예측을 위한 단순트러스모델 개선 연구)

  • Park, Woo Jin;Hwang, Hoon Hee
    • Journal of the Korean Society of Safety
    • /
    • v.30 no.5
    • /
    • pp.67-73
    • /
    • 2015
  • In this paper, the simple truss model was modified to predict the punching shear strength of long-span prestressed concrete (PSC) deck slabs under wheel load including the effects of transverse prestressing and long span length between girders. The strength of the compressive zone arounding punching cone was evaluated by the stiffness of inclined strut which was modified by considering aging effective modulus. The stiffness of springs which control lateral displacement of the roller supports consists of the steel reinforcement and prestressing which passed through the punching cone. Initial angle of struts was determined by the experimental observation to compensate for uncertainties in the complexities of the punching shear. The validity of computed punching shear strength by modified simple truss model was shown by comparing with experimental results and the experimental results were also compared with existing punching shear equations to determine level of predictability. The modified simple truss model appeared to better predict the punching shear strength of PSC deck slabs than other available equations. The punching shear strength, which was determined by snap-through critical load of modified simple truss model, can be used effectively to examine punching shear strength of long span PSC deck slabs.

A Study of Shear Reinforcement for Slab-Column Connection (슬래브-기둥 접합부의 전단보강상세에 관한 연구)

  • Baek, Sung-Woo;Kim, Jun-Seo;Choi, Hyun-Ki;Choi, Chang-Sik
    • 한국방재학회:학술대회논문집
    • /
    • 2008.02a
    • /
    • pp.37-40
    • /
    • 2008
  • The study is an experimental test on full-scale flat plate slab-column interior connection. The punching shear on the flat plate slab-column connection can bring about the reason of the brittle punching shear failure which may result of collapsing the whole structure. From the development of residential flat plate system, the shear reinforcement is developed for preventing the punching shear. For making sure of the punching shear capacity, developed for shear reinforcement in slab-column connection, the structural test is performed. The dimension of the slabs was 2620*2725*180mm with square column (600*800mm). The slabs were tested up to failure monotonic vertical shear forces. The presences of S/S bar and wire mesh substantially increased the punching shear capacity and the ductility of the slab-column connections.

  • PDF

An Experimental Study on Punching Shear of Simplified Composite Deck (초간편 강합성 바닥판의 펀칭 전단에 관한 실험적 연구)

  • Yoon, Ki-Yong;Lee, Sung-Yol;Yi, Gyu-Sei;Kim, Sang-Seup
    • Journal of the Korean Society of Hazard Mitigation
    • /
    • v.9 no.5
    • /
    • pp.23-30
    • /
    • 2009
  • According to Korea Highway Bridge Design Code the bridge deck is designed by the strength design method and is regarded as a beam possessing the unit width based on the bending theory. By many researches it is revealed that the existing bridge deck is failed by punching shear. For evaluating the ultimate capacity of bridge deck it is important to estimate the behavior of bridge deck under the punching shear. For the punching strength it is difficult that the existing research results are applied to the simplified composite deck. In this study for comparing characteristics on punching shear the punching shear tests on simplified composite deck and RC deck are performed. The punching shear strength of simplified composite deck is compared with several bridge design codes.

Punching Shear Strength of Prestressed Precast Concrete Deck (프리스트레스를 도입한 프리캐스트 콘크리트 교량바닥판의 펀칭전단강도)

  • 정철헌;류형근;정운용;김인규
    • Journal of the Korea Concrete Institute
    • /
    • v.14 no.5
    • /
    • pp.653-659
    • /
    • 2002
  • Recently, the failure case of the bridge deck slabs have been increasing in Korea and it was observed that the failure modes of most deck slabs collapsed were not caused by flexural moment but by local punching shear. The main reason of the failures was the punching shear failure of deck slabs under heavy truck traffics. This paper presents test results obtained from punching shear tests performed on prestressed precast deck specimens. Cracking patterns, failure modes, deflections, and stresses are included as well as discussion of the punching shear strength observed during punching shear tests. Static lest specimens had punching shear failures at loads much higher than predicted by the current codes. Tests results indicate that current code provisions appear to be conservative.

Estimation of Punching Shear Strength for Ultra High Performance Concrete Thin Slab (강섬유 보강 초고성능 콘크리트 슬래브의 뚫림 전단 성능 평가)

  • Park, Ji-Hyun;Hong, Sung-gul
    • Journal of Korean Association for Spatial Structures
    • /
    • v.15 no.2
    • /
    • pp.95-103
    • /
    • 2015
  • UHPC(Ultra High Performance Concrete) is used widely with its remarkable performance, such as strength, ductility and durability. Since the fibers in the UHPC can control the tensile crack, the punching shear capacity of UHPC is higher than that of the conventional concrete. In this paper, seven slabs with different thickness and fiber volume ratio were tested. The ultimate punching shear strength was increased with the fiber volume ratio up to 1%. The shear capacity of specimens with the fiber content 1% and 1.5% do not have big differences. The thicker slab has higher punching shear strength and lower deformation capacity. The critical sections of punching shear failure were similar regardless of the fiber volume ratio, but it were larger in thicker slab.

Punching Shear Strength of RC Slabs by Simple Truss Model (단순 트러스 모델에 의한 철근콘크리트 교량 바닥판의 펀칭전단강도)

  • Lee, Yongwoo;Hwang, Hoonhee
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.28 no.2A
    • /
    • pp.187-196
    • /
    • 2008
  • The punching shear strength of RC slabs is estimated analytically by the simple truss model. To avoid intrinsic difficulties in punching shear analysis of reinforced concrete slabs, the slabs were divided into three sub-structures as the punching cone and the remaining parts. The strength of the punching cone was evaluated by the stiffness of inclined strut. The stiffness of springs which control lateral displacement of the roller supports consists of the steel reinforcement which passed through the punching cone. Initial angle of struts was determined by curve fitting method of the experimental data with variable reinforcement ratio in order to compensate for uncertainties in the slab's punching shear, the simplification errors and the stiffness of the remaining sub-structures. The validity of computed punching shear strength by simple truss model was shown by comparing with experimental results. The punching shear strength, which was determined by snap-through critical load of shallow truss, can be used effectively to examine punching shear strength of RC slabs.

Development and evaluation of punching shear database for flat slab-column connections without shear reinforcement

  • Derogar, Shahram;Ince, Ceren;Mandal, Parthasarathi
    • Structural Engineering and Mechanics
    • /
    • v.66 no.2
    • /
    • pp.203-215
    • /
    • 2018
  • A large body of experiments have been conducted to date to evaluate the punching shear strength of flat slab-column connections, but it is noted that only a few of them have been considered for the development of the ACI Code provisions. The limited test results used for the development of the code provisions fall short of predicting accurately the punching shear strength of such connections. In an effort to address this shortfall and to gain an insight into the factors that control the punching shear strength of flat slab-column connections, we report a qualified database of 650 punching shear test results in this article. All slabs examined in this database were tested under gravity loading and do not contain shear reinforcement. In order to justify including any test result for evaluation punching shear database, we have developed an approved set of criteria. Carefully established set of criteria represent the actual characteristics of structures that include minimum compressive strength, effective depths of slab, flexural and compression reinforcement ratio and column size. The key parameters that significantly affect the punching shear strength of flat slab-column connections are then examined using ACI 318-14 expression. The results reported here have paramount significance on the range of applicability of the ACI Code provision and seem to indicate that the ACI provisions do not sufficiently capture many trends identified through regression of the principal parameters, and fall on the unsafe side for the prediction of the punching shear strength of flat slab-column connections.

Progressive collapse resistance of flat slabs: modeling post-punching behavior

  • Mirzaeia, Yaser;Sasani, Mehrdad
    • Computers and Concrete
    • /
    • v.12 no.3
    • /
    • pp.351-375
    • /
    • 2013
  • Post-punching resistance of a flat slab can help redistribute the gravity loads and resist progressive collapse of a structure following initial damage. One important difficulty with accounting for the post-punching strength of a slab is the discontinuity that develops following punching shear. A numerical simulation technique is proposed here to model and evaluate post-punching resistance of flat slabs. It is demonstrated that the simulation results of punching shear and post-punching response of the model of a slab on a single column are in good agreement with corresponding experimental data. It is also shown that progressive collapse due to a column removal (explosion) can lead to punching failure over an adjacent column. Such failure can propagate throughout the structure leading to the progressive collapse of the structure. Through post-punching modeling of the slab and accounting for the associated discontinuity, it is also demonstrated that the presence of an adequate amount of integrity reinforcement can provide an alternative load path and help resist progressive collapse.

Structural Behavior in Slab-Column Connections with Shear Plate Using Structural Experiment and Non-destructive Test, Spectral Analysis of Surface Waves (구조 실험과 SASW를 이용한 플랫 플레이트 기둥-슬래브접합부에서의 구조적 거동에 관한 연구)

  • Joo, Hyun-Jee;Cho, Young-Sang
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2004.05a
    • /
    • pp.48-51
    • /
    • 2004
  • This paper is to study the response of flat plate slab-column connections consisting of various types of shear reinforcement and steel plate subjected to gravity loadings, mainly punching shear forces using the non-destructive testing, spectral analysis of surface waves and structural experiments. The base specimen failed due to punching shear generated from the gravity. The three other types of slab shear reinforcement and steel plate showed effective in resisting punching shear for these types of connections under gravity loading. This study has focused in evaluating the velocity response of a Surface wave during the early age as the poured concrete specimens have been hardened, the possibility of damage detection in the slab-column connection and the relationship between the punching shear forces and the surface wave velocities under the condition that the punching shear forces had gradually increased until the flat plate slab in slab-column connection had been failed.

  • PDF

Comparison on the Failure Mechanism of Punching Shear in the Reinforced Concrete (철근 콘크리트의 뚫림전단 파괴메카니즘에 과한 비교)

  • 이주나;연규원;이호준;박찬수
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2000.04a
    • /
    • pp.533-538
    • /
    • 2000
  • In R.C. flat slab system, a brittle punching failure is a very fatal problem. But there is no generally well-defined answer to the problem and there are wide differences in current practical design codes. therefore, in this study, the factors affecting to punching failure mechanism have been studied to find out the punching shear behavior in R.C. flat slabs by comparing other investigations and practical design codes. Therefore, In this study, the factors affecting to punching failure mechanism have been studied to find out the punching shear behavior in R.C. flat slabs by comparing other investigations and practical design codes. The conclusions in this study are summarized as follows; 1) The factors affecting to punching shear are concrete strength ($f_\alpha$), ratio of column side length to slab depth (c/d), ratio of distance from column center to radial contraflexure (l/d), yield strength of steel ($f_y$), flexural reinforcement ratio ($\rho$) and size effects. 2) It is shown that th use of $\surd{f_{ck}}$in applying($f_\alpha$ to punching shear strength estimation may be more sensitive in high concrete strength. 3) The effects of l/d, ($f_y$, size are no clear in the punching failure mechanism, so in the future, it should be investigated with the effects of various composed load.

  • PDF