• Title, Summary, Keyword: Concrete Structures

Search Result 5,427, Processing Time 0.046 seconds

Performance of structures and infrastructure facilities during an EF4 Tornado in Yancheng

  • Tao, Tianyou;Wang, Hao;Yao, Chengyuan;Zou, Zhongqin;Xu, Zidong
    • Wind and Structures
    • /
    • v.27 no.2
    • /
    • pp.137-147
    • /
    • 2018
  • Heavy damages to properties with attendant losses were frequently caused by tornadoes in recent years. This natural hazard is one of the most destructive wind events that must be fully studied and well understood in order to keep the safety of structures and infrastructure facilities. On June 23, 2016, a severe tornado, which is an Enhanced Fujita (EF) 4 storm, occurred in the rim of a coastal city named as Yancheng in China. Numerous low-rise buildings as well as facilities (e.g., transmission towers) were destroyed or damaged. In this paper, damages to structures and infrastructure facilities by the severe tornado are reviewed. The collapses of residential buildings, industrial structures and other infrastructure facilities are described. With an overview of the damages, various possible mechanisms of the collapse are then discussed and utilized to reveal the initiation of the damage to various facilities. It is hoped that this paper can provide a concise but comprehensive reference for the researchers and engineers to help understand the tornado effects on structures and expose the vulnerabilities that need to be improved in current wind-resistant design practices.

Compression test of RCFT columns with thin-walled steel tube and high strength concrete

  • Xiamuxi, Alifujiang;Hasegawa, Akira
    • Steel and Composite Structures
    • /
    • v.11 no.5
    • /
    • pp.391-402
    • /
    • 2011
  • It is clear from the former researches on reinforced concrete filled steel tubular (RCFT) structures that RCFT structures have higher strength and deformation capacity than concrete filled steel tubular (CFT) structures. However, in the case of actual applications to large-scaled structures, the thin-walled steel tube must be used from the view point of economic condition. Therefore, in this study, compression tests of RCFT columns which were made by thin-walled steel tube or small load-sharing ratio in cooperation with high strength concrete were carried out, meanwhile corresponding tests of CFT, reinforced concrete (RC), pure concrete and steel tube columns were done to compare with RCFT. By the a series of comparison and analysis, characteristics of RCFT columns were clarified, and following conclusions were drawn: RCFT structures can effectively avoided from brittle failure by the using of reinforcement while CFT structures are damaged due to the brittle failure; with RCFT structures, excellent bearing capacity can be achieved in plastic zone by combining the thin-walled steel tube with high strength concrete and reinforcement. The smaller load-sharing ratio can made the reinforcement play full role; Combination of thin-walled steel tube with high strength concrete and reinforcement is effective way to construct large-scaled structures.

A Study on Evaluation Techniques of Characteristic Strength of Concrete in Existing Structures (실존 콘크리트 구조물의 특성강도 추정기법에 관한 연구)

  • 권영웅;정성철;이상윤;김민수;김인식;이지은
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • /
    • pp.703-706
    • /
    • 1998
  • Primarily, to evaluate the structural condition assessment of concrete structures, percentile strength of concrete in concrete structures should be found out. This study aims to establish the evaluation techniques for concrete strength in existing concrete structures considering the concrete quality and reliability. The results are as follows ; 1. Percentile strength of concrete in concrete structures can be estimated from following strength equation. $$f_p=f_{mea} - {\lambda}_pS_s$$2. For the calibration of above percentile strength equation with proposed codes or specifications, following sample size based on ASTM E122 can be applied.

  • PDF

Mixture rule for studding the environmental pollution reduction in concrete structures containing nanoparticles

  • Tabatabaei, Javad;Nourbakhsh, Seyed Hesam;Siahkar, Mahdi
    • Coupled systems mechanics
    • /
    • v.9 no.3
    • /
    • pp.281-287
    • /
    • 2020
  • Nanotechnology is an upcoming technology that can provide solution for combating pollution by controlling shape and size of materials at the nanoscale. This review provides comprehensive information regarding the role of nanotechnology in pollution control at concrete structures. Titanium dioxide (TiO2) nanoparticles are a good item for concrete structures for diminishing the air polluting affect by gasses of exhaust. In this article, the mixture rule is presented for the effect of nanoparticles in environmental pollution reduction in concrete structures. The compressive strength, elastic modulus and reduction of steel bars in the concrete structures are studied. The Results show that TiO2 nanoparticles have significant effect on the reduction of environmental pollution and increase of stiffness in the concrete structures. In addition, the nanoparticles can reduce the use of steel bars in the concrete structure.

Symptom-based reliability analyses and performance assessment of corroded reinforced concrete structures

  • Chen, Hua-Peng;Xiao, Nan
    • Structural Engineering and Mechanics
    • /
    • v.53 no.6
    • /
    • pp.1183-1200
    • /
    • 2015
  • Reinforcement corrosion can cause serious safety deterioration to aging concrete structures exposed in aggressive environments. This paper presents an approach for reliability analyses of deteriorating reinforced concrete structures affected by reinforcement corrosion on the basis of the representative symptoms identified during the deterioration process. The concrete cracking growth and rebar bond strength evolution due to reinforcement corrosion are chosen as key symptoms for the performance deterioration of concrete structures. The crack width at concrete cover surface largely depends on the corrosion penetration of rebar due to the expansive rust layer at the bond interface generated by reinforcement corrosion. The bond strength of rebar in the concrete correlates well with concrete crack width and decays steadily with crack width growth. The estimates of cracking development and bond strength deterioration are examined by experimental data available from various sources, and then matched with symptom-based lifetime Weibull model. The symptom reliability and remaining useful life are predicted from the predictive lifetime Weibull model for deteriorating concrete structures. Finally, a numerical example is provided to demonstrate the applicability of the proposed approach for forecasting the performance of concrete structures subject to reinforcement corrosion. The results show that the corrosion rate has significant impact on the reliability associated with serviceability and load bearing capacity of reinforced concrete structures during their service life.

Compressive behavior of rectangular sandwich composite wall with different truss spacings

  • Qin, Ying;Chen, Xin;Xi, Wang;Zhu, Xing-Yu;Chen, Yuan-Ze
    • Steel and Composite Structures
    • /
    • v.34 no.6
    • /
    • pp.783-794
    • /
    • 2020
  • Steel-concrete-steel sandwich composite wall is composed of two external steel plates and infilled concrete core. Internal mechanical connectors are used to enhance the composite action between the two materials. In this paper, the compressive behavior of a novel sandwich composite wall was studied. The steel trusses were applied to connect the steel plates to the concrete core. Three short specimens with different truss spacings were tested under compressive loading. The boundary columns were not included. It was found that the failure of walls started from the buckling of steel plates and followed by the crushing of concrete. Global instability was not observed. It was also observed that the truss spacing has great influence on ultimate strength, buckling stress, ductility, strength index, lateral deflection, and strain distribution. Three modern codes were introduced to calculate the capacity of walls. The comparisons between test results and code predictions show that AISC 360 provides significant underestimations while Eurocode 4 and CECS 159 offer overestimated predictions.

The Study of detailng for concrete reinforcement and Seismic Analysis Method for Underground Reinforced Concrete Box Structures (지하 철근 콘크리트 박스 구조물의 내진해석방법 및 철근 배근 상세에 관한 연구)

  • Lee, Myoung-Soo;Han, Sang-Chel
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.1215-1222
    • /
    • 2005
  • The object of this thesis is an study on detailing for concrete reinforcement and analytical study for seismic behavior of underground reinforced concrete box structures using the established seismic analytical method. Using the established seismic analytical method that has been presented in various documents seismic behavior of buried reinforce concrete box structures is compared. From the comparsion, it is shown that feasibility and detailing detailng for concrete reinforcement and seismic method for seismic analysis of buried reinforced concrete box structures.

  • PDF

Improving Durability Performance of Reinforced Concrete Structures with Probabilistic Analysis

  • Ferreira, Rui Miguel
    • International Journal of Concrete Structures and Materials
    • /
    • v.2 no.2
    • /
    • pp.137-143
    • /
    • 2008
  • In recent years, much research work has been performed on durability design and long-term performance of concrete structures in marine environments. In particular, the development of new procedures for probability-based durability design has been shown to provide a more realistic basis for the analysis. This approach has been successfully applied to several new concrete structures, where requirements for a more controlled durability and service life have been specified. For reinforced concrete structures in a marine environment, it is commonly assumed that the dominant degradation mechanism is the corrosion of the reinforcement due to the presence of chlorides. The design approach is based on the verification of durability limit states, examples of which are: depassivation of reinforcement, cracking and spalling due to corrosion, and collapse due to cross section loss of reinforcement. With this design approach the probability of failure can be determined as a function of time. In the present paper, a probability-based durability performance analysis is used in order to demonstrate the importance of the durability design approach of concrete structures in marine environments. In addition, the sensitivity of the various durability parameters affecting and controlling the durability of concrete structures in a marine environment is studied. Results show that the potential of this approach to assist durability design decisions making process is great. Based the crucial information generated, it is possible to prolong the service life of structures while simultaneously optimizing the final design solution.

Evaluation of Alkali Recovery Agents (알칼리회복제의 성능평가)

  • Lee, Chin-Yong;Kim, Dong-Wan
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • /
    • pp.637-640
    • /
    • 2006
  • Due to contaminated environment many concrete structures are carbonated. It causes the corrosion of rebar and induces the cracks of concrete, eventually. This study investigates the mechanism and properties of the alkali recovery agents(ARA) which are currently applied for repairing concrete structures on sites. The results indicate that the ARAs are not sufficiently effective to the realkalization of concrete structures.

  • PDF

Non-linear Analysis of Passive Confined Concrete Structures using Tri-Survace Concrete Model (Tri-Surface 콘크리트 모델을 이용한 수동 구속된 콘크리트의 비선형 해석)

  • 조병완;김장호;김영진
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • /
    • pp.604-607
    • /
    • 2003
  • Recently, hybrid concrete structures such as a concrete-filled steel tubular(CFT), a steel reinforced concrete(SRC) and a composite material are popular in structure applications. They also have merit of high strength, high ductility, and large energy absorption capacity. But the analysis of hybrid concrete structures is very difficult owing to the complex behavior of concrete under passive confinement. This paper has analyzed CFT, which receives passive confinement using Tri-Surface concrete model for three dimension finite element analysis. By the result of that, the proposed model was properly forecasted a concrete behavior that receives passive restraint as well as non-linear analysis of concrete which receive uniaxial stress and high active confinement of 400Mpa. If the model through the steady study is set up especially on the factor of concrete under passive confinement, the proposed concrete model will be surely useful for analysis of the hybrid concrete structures.

  • PDF