Analysis and modelling of the seismic behaviour of high ... - Ingegneria

More documents

Recommendations

Info

3. SEISMIC BEHAVIOUR OF BOLTED END PLATE BEAM-TO-COLUMN STEEL JOINTS response - influenced by the geometrical and mechanical parameters defining the key structural components, i.e. the end plate, the bolts, the column flange and web, the column panel zone - makes the experimental analysis vital research tool. Numerous studies were also devoted to the simulation of joint behaviour through numerical methods, in particular FE analysis with interesting results, which complemented the test outcomes permitting their extension to a larger range of cases of practical interest (Nethercot & Zandonini, 1988; Bose et al, 1996; Bursi and Jaspart, 1997; Bursi and Jaspart, 1998; Bahaari and Sherbourne, 2000). Despite important continuous advances in FE analysis, which enable more and more refined approximations, the reliability of the results is still remarkably affected by the importance of localised effects, e.g., the evolution of plate-contact area, bolt- plate interaction, low ductility of the Heat Affected Zones (HAZ) near welds, etc. Besides, the associated burden makes this approach unfeasible in design practice, and its cost efficiency remains rather low even for research purposes. However, the knowledge of the behaviour of end plate connections under static loading was more than adequate to develop and validate design models, which meet the recent demand of semi-continuous frame design. An extended end plate connection consists of a plate with bolt holes drilled or punched, and shop welded to a beam section. The connection is completed in the field when the beam end is bolted to a column. The extended end plate connection is termed “extended” because the plate extends above or below the flange that will be in tension under monotonic loading. In the case of extended end plate devoted to seismic design, the end plate is extended above and below beam flanges. The behaviour of this type of connection under cyclic loading has been investigated, though at a lower extent than for the static case, and the main features clearly identified, including the stiffness and strength deterioration, the dependence on the loading history, and the typical modes of failure (Ghobarah et al, 1990; Ghobarah et al, 1992; Bernuzzi et al, 1996; Kukreti and Biswas, 1997; Adey et al, 1998). On the one hand, the increasing degree of complexity of the phenomena involved with respect to the monotonic case is apparent, like also the higher difficulty in setting up a model capable of approximating the hysteretic behaviour under any type of loading history, with the accuracy level required in seismic design (Deng et al, 2000). On the other hand, recent studies pointed out that moment resisting semi-continuous steel frames can possess a satisfactory seismic performance at competitive cost (Nader & Astaneh, 1991), which underlines once more the lack of simplified, yet reliable, design criteria and joint models. Such a limited knowledge hampers the practical use of semi-rigid frames in seismic areas, despite they are accepted by recent Codes (AISC, 1997 and Eurocode 8, 2002). 45
3. SEISMIC BEHAVIOUR OF BOLTED END PLATE BEAM-TO-COLUMN STEEL JOINTS 3.4 The experimental programme carried out at the DIMS The study intends to discuss the main outcomes of research work related to the experimental analysis of the cyclic behaviour of end plate joints and their Tee-stub components, conducted by the Department of Mechanical and Structural Engineering (DIMS) of the University of Trento. This study aims at developing joint models enabling their seismic response to be captured in all its aspects, including the damage initiation and evolution up to and at failure. The results of the extensive experimental analysis were evaluated in terms of the main behavioural parameters of interest in seismic design. They were then used to appraise the component method, because of the particular interest in the extension of the model to the cyclic range. Within a plane frame, an exterior joint connecting an IPE beam with an HE exterior column is considered. In accordance with the Eurocode 3, the key component, on which the attention is focussed, is assumed to be the Tee stub. Along this line, isolated Tee stubs (ITS), Complete Tee stubs (CTS) and Complete Joints (CJ) have been tested. The overall programme consists of 36 tests on three sets of specimens of different complexity in terms of number of components involved: the first set of specimens is illustrated in Figure 3.3a and comprises 10 Isolated Tee Stub connections assumed to be the elemental components of end plate connections. The basic geometrical characteristics of ITS connections are collected in Columns 2 of Table 3.1 while the corresponding bolt diameters are gathered in Column 3. The second 8 specimens coupling a Tee stub with a column section as depicted schematically in Figure 3.3b. These specimens reflect both the behaviour of ITS and of column components. Relevant properties of CTS specimens are collected in Table 3.2. Moreover, ITS and column stubs are coupled to generate different typical thickness over bolt diameter ratios. The third set includes 18 complete beam-to-column joints. Specimens are illustrated schematically in Figure 3.3c while the corresponding geometrical properties are reported in Table 3.3. Specimens were designed to achieve a partial strength and ductile behaviour through plasticity both at the beam-to-column connection and at the column web panel. The parameters investigated where: 46 • the joint geometry in terms of: end plate thickness 12 and 18mm, bolt diameter, 16, 20 and 24 mm, column section, i.e. HEA180 and 280, HEB180 and 280; • the loading history: 7 histories depicted in Figure 3.4 were considered in addition to the monotonic loading.
Page 1 and 2:
Dipartimento di Ingegneria Meccanic
Page 3 and 4:
UNIVERSITÀ DEGLI STUDI DI TRENTO D
Page 6:
Ai miei genitori
Page 10 and 11: INDEX 1 INTRODUCTION...............
Page 12 and 13: INDEX iii 4.10.3 Results of the PsD
Page 14 and 15: 1.1 Introduction 1 1 INTRODUCTION I
Page 16 and 17: 1. INTRODUCTION imposes precise con
Page 18 and 19: 1. INTRODUCTION joints whilst 2D mo
Page 20 and 21: 7 2 DUCTILITY AND SEISMIC RESPONSE
Page 22 and 23: 2. DUCTILITY AND SEISMIC RESPONSE O
Page 54 and 55: 3. SEISMIC BEHAVIOUR OF BOLTED END
Page 108 and 109:
3. SEISMIC BEHAVIOUR OF BOLTED END
Page 110 and 111:
Page 112 and 113:
Page 114 and 115:
4. SEISMIC RESPONSE OF PARTIAL-STRE
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
Page 124 and 125:
Page 126 and 127:
Page 128 and 129:
Page 130 and 131:
Page 132 and 133:
Page 134 and 135:
Page 136 and 137:
Page 138 and 139:
Page 140 and 141:
Page 142 and 143:
Page 144 and 145:
Page 146 and 147:
Page 148 and 149:
Page 150 and 151:
Page 152 and 153:
Page 154 and 155:
Page 156 and 157:
Page 158 and 159:
Page 160 and 161:
Page 162 and 163:
Page 164 and 165:
Page 166 and 167:
Page 168 and 169:
Page 170 and 171:
Page 172 and 173:
Page 174 and 175:
Page 176 and 177:
Page 178 and 179:
Page 180 and 181:
Page 182 and 183:
Page 184 and 185:
Page 186 and 187:
Page 188 and 189:
5. SEISMIC BEHAVIOUR OF RC COLUMNS
Page 190 and 191:
Page 192 and 193:
Page 194 and 195:
Page 196 and 197:
Page 198 and 199:
Page 200 and 201:
Page 202 and 203:
Page 204 and 205:
Page 206 and 207:
Page 208 and 209:
Page 210 and 211:
Page 212 and 213:
Page 214 and 215:
Page 216 and 217:
Page 218 and 219:
Page 220 and 221:
Page 222 and 223:
Page 224 and 225:
Page 226 and 227:
Page 228 and 229:
Page 230 and 231:
Page 232 and 233:
Page 234 and 235:
Page 236 and 237:
Page 238 and 239:
Page 240 and 241:
Page 242 and 243:
Page 244 and 245:
Page 246 and 247:
Page 248 and 249:
Page 250 and 251:
Page 252 and 253:
Page 254 and 255:
Page 256 and 257:
Page 258 and 259:
6. SUMMARY, CONCLUSIONS AND FUTURE
Page 260 and 261:
Page 262:
show all

Analysis and modelling of the seismic behaviour of high ... - Ingegneria

Create successful ePaper yourself

Delete template?

Save as template?