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CONTENTS
Volume 10, Number 6, December 2010
 

Abstract
Most of steel structures in various industries are subjected to corrosion due to environmental exposure. Corrosion damage is a serious problem for these structures which may reduce their carrying capacity. These aging structures require maintenance and in many cases, replacement. The goal of this research is to consider the effects of corrosion by developing a model that estimates corrosion loss as a function of exposure time. The model is formulated based on average measured thickness data collected from three severely corroded I-beams (nearly 30 years old). Since corrosion is a time-dependent parameter. Analyses were performed to calculate the lateral buckling capacity of steel beam in terms of exposure time. Minimum curves have been developed for assessment of the remaining lateral buckling capacity of ordinary I-beams based on the loss of thicknesses in terms of exposure time. These minimum curves can be used by practicing engineers for better estimates on the service life of corrosion damaged steel beams.

Key Words
steel structures; exposure time; corroded beams; lateral buckling

Address
Reza Rahgozar,Mohsen Malekinejad: Civil Engineering Department, University of Kerman, Kerman, Iran
Yasser Sharifi: Civil Engineering Department, University of Rafsanjan, Rafsanjan, Iran

Abstract
The rigid connections of I-beams to Rectangular Hollow Sections (RHS) in steel structures usually behave as semi-rigid connection. This behavior is directly related to the column face deformation. The deformation in the wall of RHS column in the connection zone causes a relative rotation between beam end and column axis, which consequently reduces the rigidity of beam-column connection. In the present paper, the percentages of connection rigidity reduction for serviceability conditions are evaluated by using the finite element analysis. Such percentages for RHS columns without internal stiffeners are considerable, and can be calculated from presented graphs

Key Words
steel frames; rigid-connection; semi-rigid connection; finite element; box column; rectangular hollow section

Address
Civil and Environmental Eng. Department, Shiraz University of Technology, Shiraz, Iran

Abstract
This paper is aiming to study the performances of reinforced high-strength concrete (HSC) short columns confined with aramid fibre-reinforced polymer (AFRP) sheets. An experimental program, which involved 45 confined columns and nine unconfined columns, was carried out in this study. All the columns were circular in cross section and tested under axial compressive load. The considered parameters included the concrete strength, amount of AFRP layers, and ratio of hoop reinforcements. Based on the experimental results, a prediction model for the axial stress-strain curves of the confined columns was proposed. It was observed from the experiment that there was a great increment in the compressive strength of the columns when the amount of AFRP layers increases, similar as the ultimate strain. However, these increments were reduced as the concrete strength increasing. Comparisons with other existing prediction models present that the proposed model can provide more accurate predictions

Key Words
high-strength concrete (HSC); reinforced concrete column; aramid fibre-reinforced polymer (AFRP); experiment; prediction model

Address
Han-Liang Wu: School of Civil Engineering, Beijing Jiaotong University, Beijing, 100044, China
Yuan-Feng Wang: Bridge Technology Research Center, Research Institute Center of Highway, Ministry of Transportation, Beijing, 100088, China

Abstract
This paper presents the axial compressive behaviour of stub concrete-filled columns with elliptical stainless steel and carbon steel hollow sections. The finite element method developed via ABAQUS/Standard solver was used to carry out the simulations. The accuracy of the FE modelling and the proposed confined concrete stress-strain model were verified against experimental results. A parametric study on stub concrete-filled columns with various elliptical hollow sections made with stainless steel and carbon steel was conducted. The comparisons and analyses presented in this paper outline the effect of hollow sectional configurations to the axial compressive behaviour of elliptical concrete-filled steel tubular columns, especially the merits of using stainless steel hollow sections is highlighted

Key Words
concrete-filled column; elliptical hollow section; stainless steel; nonlinear finite element model; axial compressive behaviour; parametric study

Address
School of Engineering Design and Technology, University of Bradford, UK

Abstract
This paper presents finite element analyses, experimental measurements and finite element model updating of an arch type steel laboratory bridge model using semi-rigid connections. The laboratory bridge model is a single span and fixed base structure with a length of 6.1 m and width of 1.1m. The height of the bridge column is 0.85 m and the maximum arch height is 0.95 m. Firstly, a finite element model of the bridge is created in SAP2000 program and analytical dynamic characteristics such as natural frequencies and mode shapes are determined. Then, experimental measurements using ambient vibration tests are performed and dynamic characteristics (natural frequencies, mode shapes and damping ratios) are obtained. Ambient vibration tests are performed under natural excitations such as wind and small impact effects. The Enhanced Frequency Domain Decomposition method in the frequency domain and the Stochastic Subspace Identification method in the time domain are used to extract the dynamic characteristics. Then the finite element model of the bridge is updated using linear elastic rotational springs in the supports and structural element connections to minimize the differences between analytically and experimentally estimated dynamic characteristics. At the end of the study, maximum differences in the natural frequencies are reduced on average from 47% to 2.6%. It is seen that there is a good agreement between analytical and experimental results after finite element model updating. Also, connection percentages of the all structural elements to joints are determined depending on the rotational spring stiffness

Key Words
ambient vibration test; dynamic characteristics; enhanced frequency domain decomposition; laboratory bridge model; rotational spring; semi-rigid connection; stochastic subspace identification

Address
Ahmet Can Altuni ik, Alemdar Bayraktar, Suleyman Adanur: Karadeniz Technical University, Department of Civil Engineering, 61080, Trabzon, TURKEY

Bar Sevm : Gumu hane University, Department of Civil Engineering, 29100, Gumu hane, TURKEY

Murat Emre Kartal : Zonguldak Karaelmas University, Department of Civil Engineering, 67100, Zonguldak, TURKEY


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