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CONTENTS
Volume 15, Number 1, July 2013
 

Abstract
Predicting the fire resistance of structures has been significantly advanced by full scale fire tests in conjunction with improved understanding of compartmental fire. Despite the progress, application of insulation is still required to parts of structural steelwork to achieve over 60 minutes of fire rating. It is now recognised that uncertainties on insulation properties hinder adaptation of performance based designs for different types of structures. Intumescent coating has recently appeared to be one of most popular insulation types for steel structures, but its design method remains to be confirmed by empirical data, as technical difficulties on the determination of the material properties at elevated temperatures exist. These need to take into account of further physiochemical transitions such as moving boundary and endothermic reaction. The impetus for this research is to investigate the applicability of the conventional differential equation solution which examines the temperature rise on coated steel members by an inorganic intumescent coating, provided that the temperature.dependent thermal/mechanical insulation properties are experimentally defined in lab scale tests.

Key Words
intumescent coating; temperature assessment; thermal property; steel structure

Address
(1) J. Yoon Choi: Fire Safety Team, Division of Built Environment, Korea Conformity Laboratories, Seocho-dong, Seoul, 137-867, Republic of Korea;
(2) Sengkwan Choi: School of the Built Environment, University of Ulster, Newtownabbey, BT37 0QB, UK.

Abstract
The sensitivities of a structural response due to variation of its design parameters are prerequisite in the majority of the algorithms used for fundamental problems in engineering as system uncertainties, identification and probabilistic assessments etc. The paper presents the concept of probabilistic sensitivity of suspension bridges with respect to near-fault ground motion. In near field earthquake ground motions, large amplitude spectral accelerations can occur at long periods where many suspension bridges have significant structural response modes. Two different types of suspension bridges, which are Bosporus and Humber bridges, are selected to investigate the near-fault ground motion effects on suspension bridges random response sensitivity analysis. The modulus of elasticity is selected as random design variable. Strong ground motion records of Kocaeli, Northridge and Erzincan earthquakes are selected for the analyses. The stochastic sensitivity displacements and internal forces are determined by using the stochastic sensitivity finite element method and Monte Carlo simulation method. The stochastic sensitivity displacements and responses obtained from the two different suspension bridges subjected to these near-fault strong-ground motions are compared with each other. It is seen from the results that near-fault ground motions have different impacts stochastic sensitivity responses of suspension bridges. The stochastic sensitivity information provides a deeper insight into the structural design and it can be used as a basis for decision-making.

Key Words
probabilistic sensitivity; stochastic sensitivity finite element method; Monte Carlo Simulation; suspension bridge

Address
Ozlem Cavdar: Gumushane University, Department of Civil Engineering, 29000, Gumushane, Turkey.

Abstract
This paper presents a numerical study of axially loaded concrete-filled steel tubular columns with \"T\" shaped cross section (CFTTS) based on the ABAQUS standard solver. Two types of columns with \"T\" shaped cross section, the common concrete-filled steel tubular columns with \"T\" shaped cross section (CCFTTS) and the double concrete-filled steel tubular columns with \"T\" shaped cross section (DCFTTS), are discussed. The failure modes, confining effects and load-displacement curves are analyzed. The numerical results indicate that both have the similar failure mode that the steel tubes are only outward buckling on all columns\' faces. It is found that DCFTTS columns have higher axial capacities than CCFTTS ones duo to the steel tube of DCFTTS columns can plays more significant confining effect on concrete. A parametric study, including influence of tube thickness, concrete strength and friction coefficient of tube-concrete interface on the axial capacities is also carried out. Simplified formulae were also proposed based on this study.

Key Words
axial capacity; concrete-filled steel tube; T-shaped cross section; confining effect

Address
Qin-Ting Wang and Xu Chang: College of Civil Engineering; Henan Polytechnic University; Jiaozuo City, Henan Province, 454000; People\'s Republic of China.

Abstract
This paper studies the dynamic instability of laminated composite plates under thermal and arbitrary in-plane periodic loads using first-order shear deformation plate theory. The governing partial differential equations of motion are established by a perturbation technique. Then, the Galerkin method is applied to reduce the partial differential equations to ordinary differential equations. Based on Bolotin\'s method, the system equations of Mathieu-type are formulated and used to determine dynamic instability regions of laminated plates in the thermal environment. The effects of temperature, layer number, modulus ratio and load parameters on the dynamic instability of laminated plates are investigated. The results reveal that static and dynamic load, layer number, modulus ratio and uniform temperature rise have a significant influence on the thermal dynamic behavior of laminated plates.

Key Words
dynamic instability; laminated plates; Bolotin\'s method; temperature

Address
(1) Chun-Sheng Chen, Ching-Long Wei: Department of Mechanical Engineering, Lunghwa University of Science and Technology, Guishan Shiang 33306, Taiwan;
(2) Ting-Chiang Tsai: Department of Mechanical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan;
(3) Wei-Ren Chen: Department of Mechanical Engineering, Chinese Culture University, Taipei 11114, Taiwan.

Abstract
In this paper a robust 2-noded connection element has been developed for modelling the bolted end-plate connection between steel beam and column at elevated temperatures. The numerical procedure described is based on the model proposed by Huang (2011), incorporating additional developments to more precisely determinate the tension, compression and bending moment capacities of end-plate connection in fire. The proper failure criteria are proposed to calculate the tension capacity for each individual bolt row. In this new model the connection failure due to bending, axial tension, compression and shear are considered. The influence of the axial force of the connected beam on the connection is also taken into account. This new model has the advantages of both the simple and component-based models. In order to validate the model a total of 22 tests are used. It is evident that this new connection model has ability to accurately predict the behaviour of the end-plate connection at elevated temperatures, and can be used to represent the end-plate connections in supporting performance-based fire resistance design of steel-framed composite buildings.

Key Words
end-plate connection; component-based model; fire resistance; steel structures; T-stub

Address
Shuyuan Lin, Zhaohui Huang and Mizi Fan: School of Engineering and Design, Brunel University, Uxbridge, Middlesex, UB8 3PH, UK.

Abstract
Fire performance and fire safety of high-rise buildings have become major concerns after the disasters of World Trade Center in the U.S. in 2001 and Windsor tower in Spain in 2005. Performance based design (PBD) approaches have been considered as a better method for fire resistance design of structures because it is capable of incorporating test results of most recent fire resistance technologies. However, there is a difficulty to evaluate fireproof performance of large structures, which have multiple structural members such as columns, slabs, and walls. The difficulty is mainly due to the limitation in the testing equipment, such as size of furnace that can be used to carry out fire tests with existing criteria like ISO 834, BS 476, and KS F 2257. In the present research, a large scale calorie meter (10 MW) was used to conduct three full scale fire tests on medical modular blocks. Average fire load of 13.99 kg/m2 was used in the first test. In the second test, the weighting coefficient of 3.5 (the fire load of 50 kg/m2) was used to simulate the worst fire scenario. The flashover of the medical modular block occurred at 62 minutes in the first test and 12 minutes in the second test. The heat resistance capacity of the external wall, the temperatures and deformations of the structural members satisfied the requirements of fire resistance performance of 90 minutes burning period. The total heat loads and the heat values for each test are calculated by theoretical equations. The duration of burning was predicted. The predicted results were compared with the test results, and they agree quite well.

Key Words
full-scale fire test; modular block; fire load; fire resistance

Address
(1) Hyung-Jun Kim: Fire Safety Research Center, Korea Institute of Construction Technology, 64, Mado-ro 182beon-gil, Mado-myeon, Hwaseong-si, Gyeonggi-do, 445-861, Republic of Korea;
(2) Jae-Sung Lee: Department of Architectural Engineering, Hannam University, 70, Hannam-ro, Daedeok-gu, Daejeon 306-818, Republic of Korea;
(3) Hung-Youl Kim: Fire Safety Research Center, Korea Institute of Construction Technology, 64, Mado-ro 182beon-gil, Mado-myeon, Hwaseong-si, Gyeonggi-do 445-861, Republic of Korea;
(4) Bong-ho Cho: Department of Architectural Engineering, Ajou University, 206, World cup-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 443-749, Republic of Korea;
(5) Yunping Xi: Department of Civil, Environmental, and Architectural Engineering, University of Colorado, 1800 Grant Street, Suite 800, USA;
(6) Ki-hyuck Kwon: Department of Architecture Engineering, University of Seoul, Seoul city, Republic of Korea.


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