Seismic Vulnerability Assessment for Steel Structures

Abstract

Steel structures are often used in building constructions. However, in seismic area these structures could suffer heavy damages, especially those build according ancient seismic codes. To assess the seismic vulnerability of such structures, studies must be conducted. The aim of the present work is to develop a simple method which gives a state of a studied building according the seismic code in practice. This method is called “Vulnerability index method” and aimed to identify the most important parameters that play a role in the seismic behavior of steel structures. Then weighting factors are determined letting the calculation of a vulnerability index. Then, the studied building is classified according a given classification. Two examples were given to show the efficiency of the method. KEYWORD: Seismic vulnerability; Steel structures; Vulnerability index; Seismic parameters International Conference on Industrial Technology and Management Science (ITMS 2015) © 2015. The authors Published by Atlantis Press 1237 Table 1. Ductility according the behavior factor for steel frame structures. Ductility level Value of R High Ductility: Class A [6 – 4 [ Average Ductility: Class B [4 2 [ Low Ductility: Class C < 2 3 QUANTIFICATION OF EACH PARAMETER Weighting factors for each parameter are proposed on table II. These factors were deduced from a statistical study based on the seismic feedback experience from past earthquakes in Algeria (Ain Temouchen 1999 and Zemouri 2003). Three classes are considered and a parameter can take only one factor. For each parameter and each category considered, a coefficient (ki) is identified expressing its seismic quality (Table 2). The “Details” parameter was specified as follows: studwork, dividing walls, balconies, railing, cornices, chimneys, ventilation space, electrical network, gas network, water network and sewage network. Table 2. Weighting factor “Ki”. N Parameters Classes/Ki Class A Class B Class C 1 Ductility 0.00 0.08 0.15 2 Bearing capacity 0.02 0.07 0.09 3 Assemblage 0.02 0.06 0.15 4 General maintenance conditions 0.08 0.06 0.08 5 Type of soil 0.03 0.04 0.05 6 Floor 0.03 0.04 0.05 7 Buckling 0.03 0.06 0.08 8 Plan regularity 0.03 0.04 0.05 9 Modifications 0.03 0.04 0.05 10 Elevation regularity 0.03 0.04 0.05 11 Pounding effect 0.03 0.04 0.05 12 Ground conditions 0.03 0.04 0.05 13 Roof 0.03 0.04 0.05 14 Details 0.03 0.04 0.05 Three classes are defined for each parameter. Each considered parameter can belong to one of the three defined classes A, B, and C. These classes are declined as follows:  Class A expresses a parameter inducing a good behaviour of the structure during an earthquake  Class C, expresses a parameter inducing a bad behaviour of the structure during an earthquake  Class B expresses an intermediate behaviour of the structure during an earthquake. Then, the vulnerability index, VI, of a construction is expressed according to the formula (1):