The Design of Modern Steel Bridges - TEDI

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182 The Design of Modern Steel Bridges References Central stiffener: Bending moment ¼ 4pEIe ðm 1Þ=L 2 ¼ 4p 205 000 Ie 10:05 3000 0:111 2 ¼ 0:319Ie Max stress ¼ 144:5 þ 0:319 50:54 ¼ 144:5 þ 16:1 ¼ 160:6N=mm 2 Outer stiffener: Bending moment ¼ 146:7 12 831 10:05 N mm Max stress ¼ 146:7 þ 146:7 12 831 10:05 These magnitudes are less than ¼ 146:7 þ 14:7 ¼ 161:4N=mm 2 sy 355 ¼ ¼ 268:9N=mm2 gmgf3 1:20 1:1 50:54 64:84 10 6 Hence the compression flange design is satisfactory. The maximum stress at outstand tip of mid-span section, and at flange plate and outstand tip at support section, can be checked by combining the orthotropic analysis with the procedure given at (a)(ii) and (b). 1. Timoshenko S. P. and Gere J. M. (1961) Theory of Elastic Stability. McGraw-Hill Book Company. 2. Chatterjee S. (1978) Ultimate load analysis and design of stiffened plates in compression. PhD thesis, London University. 3. BS 5400: Part 3: 2000. Code of Practice for Design of Steel Bridges. British Standards Institution, London.
Chapter 7 Cable-stayed Bridges 7.1 History A brief history of cable-stayed type of bridge construction is included in Chapter 1. This section provides a more detailed account of the gradual technological developments leading up to the present state-of-the-art of this type of bridges. The concept of providing intermediate support to a beam by inclined ties hanging from a tower or mast dated back to ancient times. The Egyptians built sailing ships by applying this idea. In the Far East, rivers were spanned by bamboo bridges supported by vines attached to trees on the banks. In 1617 Faustus Verantius of Venice designed a timber deck bridge supported by several inclined eye-bars attached to masonry towers, and in 1784 a German carpenter Immanuel Löscher built in Freibourg a 32 m span timber bridge supported by timber stays attached to a timber tower[1]. In 1817 British engineers Redpath and Brown built the 33.6 m span King’s Meadows footbridge using inclined wire cables to support lattice longitudinal girders in the outer thirds of their spans from the tops of two cast-iron towers. Quite a few bridges were subsequently built in various parts of Europe, with wrought iron bars, chains, wires or even timber stays supporting metal or timber decks from towers; but many of them collapsed in strong wind. These stays could not be tightened during erection and hence they were only effective after a substantial deflection of the deck. Cable stays were successfully adopted by John Roebling in America to provide crucially needed extra stiffness and aerodynamic stability to his great suspension bridges, the first being the Grand Trunk Bridge across the Niagara opened in 1885, then the bridge over the Ohio in Cincinnati opened in 1867, and the most striking being the Brooklyn Bridge in New York (Figure 1.9) opened in 1883. The Franz Joseph Bridge in Prague and the Albert Bridge in London (Figure 1.8) designed by Ordish and opened in 1868 and 1873, respectively, had a combination of suspension and stay rods, but the cable formed by the suspension rods was used only to hold the diagonal stay rods. In the second half of the nineteenth century in France Arnodin built several bridges of span up to 163 m with the central portion of the span supported by hangers from two suspension cables and stay cables radiating from the tower tops supporting the outer portions of the span. This system 183
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The Design of Modern Steel Bridges
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The Design of Modern Steel Bridges
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Contents Preface vii Acknowledgemen
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Preface Bridges are great symbols o
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Acknowledgements The figures in Cha
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2 The Design of Modern Steel Bridge
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10 The Design of Modern Steel Bridg
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Table 2.1 Properties of some commer
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Chapter 3 Loads on Bridges 3.1 Dead
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3.3 Design live loads in different
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interstate highways are designed fo
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a coefficient that depends on the n
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Loads on Bridges 59 In Germany, a n
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Table 3.6 Typical values of U and P
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3.5 Longitudinal forces on bridges
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wind loading on the traffic. An upl
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where r is the air density ¼ 1.226
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Loads on Bridges 69 minimum and max
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3.8 Other loads on bridges There ar
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References Loads on Bridges 73 wher
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Chapter 4 Aims of Design 4.1 Limit
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critical components of the structur
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But this is an attempt to achieve u
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If the basic variables R and S are
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educed variables defined by oi ¼ x
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will have a probability of failure
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Aims of Design 87 g m ¼ g m1 g m2
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Table 4.2 Failure probabilities of
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Chapter 5 Rolled Beam and Plate Gir
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as possible. But deep and thin webs
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eam, with an effective area equal t
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and stresses caused by lateral defl
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Figure 5.3 Beam cross-section. In t
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Rolled Beam and Plate Girder Design
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Table 5.2 Effective length factors
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stress is equal to p 2 E/(Le/r) 2 )
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equation (5.16) has been adopted fo
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The strain energy of the elastic re
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Figure 5.6 Buckling of plates in co
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Figure 5.8 Buckling of plate under
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techniques. It may be noted that th
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5.4.3 Effect of residual stresses R
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Aw ¼ 40 mm 2 , allowing for a smal
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Basler and Thurlimann were the firs
Page 143 and 144: Ostapenko/Chern gave the following
Page 145 and 146: where m ¼ Mp b 2 twsyw ty ¼ syw p
Page 147 and 148: the case of equal flanges, the tota
Page 149 and 150: emains flat until an elastic critic
Page 151 and 152: Rolled Beam and Plate Girder Design
Page 153 and 154: longitudinal compression is given b
Page 155 and 156: where Peq ¼ s1tB PE Ps Pcro Peq1
Page 157 and 158: Figure 5.27 Tension-field forces in
Page 159 and 160: 5.5.6 Design of longitudinal web st
Page 161 and 162: when Le is the effective length for
Page 163 and 164: pffiffiffiffiffiffiffiffiffiffiffif
Page 165 and 166: een derived as a condition for trea
Page 167 and 168: For interaction of various stress c
Page 169 and 170: must be at least i.e. 1 IsxbB 4 2 a
Page 171 and 172: Chapter 6 Stiffened Compression Fla
Page 173 and 174: Stiffened Compression Flanges of Bo
Page 175 and 176: cross-section in which the secant s
Page 177 and 178: longitudinal compression of the lon
Page 179 and 180: webs of main girders is denoted by
Page 183 and 184: wherefrom Ms ¼ 2 3 PE P The net be
Page 193: Stiffened Compression Flanges of Bo
Page 197 and 198: Cable-stayed Bridges 185 cables con
Page 199 and 200: The following is a list of cable-st
Page 201 and 202: (a) Fan system (b) Harp system (c)
Page 203 and 204: 7.3.2 Ropes causing lateral compres
Page 205 and 206: The spiral winding of wires around
Page 207 and 208: polyethylene or even steel tube. Or
Page 209 and 210: See Fig. 7.7. Imagine a cable-stay
Page 211 and 212: It may be noted that: Et is higher
Page 213: Reference Cable-stayed Bridges 201
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