Aluminium Design and Construction John Dwight

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Table 10.1 Elements of sections—properties referred to axes through element centroid Notes. 1. Refer to Figure 10.6 for element details. 2. In case 2 and 11–14 it is assumed that t is small relative to b or r. Copyright 1999 by Taylor & Francis Group. All Rights Reserved.
10.3.3 Product of inertia The product of inertia I xy , appearing in Section 10.3.2, can be either positive or negative. It may be calculated using the following expression in which the summations are for all the elements of the section: (10.13) where I Exy =an element’s ‘own’ product of inertia, referred to parallel axes Ex and Ey through its centroid E, A E =area of the element (taken positive), and X E , y E= coordinates of E referred to the main axes Gx and Gy, with strict attention to signs. Table 10.1 includes expressions for I Exy for the common element shapes shown in Figure 10.6. In applying these, it is important to realize that I Exy can be either positive or negative, depending on which way round the element is drawn. As drawn in the Figure, it is positive in every case. But if the element is reversed (left to right) or inverted, it becomes negative. If it is reversed and inverted, it becomes positive again. 10.3.4 Inertia of the effective section The elastic section properties should when necessary be based on an effective section, to allow for HAZ softening, local buckling or holes. There are two possible methods for so doing. In method 1, we take effective thicknesses in the nominal HAZ regions (Section 6.6.1) and effective stress blocks in slender elements (Chapter 7), I being calculated accordingly. The HAZ softening factor kz is put equal to kz2. If the section is semi-compact, there are no slender elements and thus no deductions to be made for local buckling. In method 2, we treat the effective section as being composed of all the actual elements that constitute the gross section, on which are then super-imposed appropriate negative elements (i.e. ‘lost areas’). In any HAZ region, the lost area is Az (1-kz2 ). In a slender element it consists of the ineffective material between effective stress blocks (internal elements), or at the toe (outstands). I is obtained basically as in Section 10.3.1 or 10.3.2, combining the effect of all the positive elements (the gross section) with that of the negative ones (the lost areas), and taking AE , IExx , IEyy and IExy with reversed sign in the case of the latter. In considering the lost area due to softening at a longitudinal weld, there is no need to locate the HAZ’s centroid with great precision. Method 2 tends to be quicker for sections with small longitudinal welds, since it only involves a knowledge of Az without having to find the actual distribution of HAZ material. Copyright 1999 by Taylor & Francis Group. All Rights Reserved.
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Aluminium Design and Construction C
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First published 1999 by E & FN Spon
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2.2.1 Rolling mill practice 2.2.2 P
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5 Limit state design and limiting s
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8.2.6 Use of interpolation for semi
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10.3.2 Inertias for a section with
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Preface Aluminium is easily the sec
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List of symbols The following symbo
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uu, vv principal axes w effective s
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1.1.3 The industrial metal It is on
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where A is the section area (mm 2 )
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1.3.1. The good points about alumin
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Deflection Because of the lower mod
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1.4.4 Establishment of the alloys I
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1.5.2 New technology Most of alumin
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large span, where self-weight is a
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These tend to be in all-aluminium c
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Close-up of the M-dec system, which
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Aluminium glazing system for commer
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Nat West Media Centre, Lords Cricke
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The main requirements for the produ
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in which t and w are in mm. These a
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Figure 2.1 Extrusion process (direc
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Figure 2.2 Typical extrusion die. t
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Figure 2.6 ‘Semi-hollow’ profil
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especially the stronger alloys in t
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Figure 2.9 Conventional profiles. 2
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2.4 TUBES By tubes we mean hollow s
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CHAPTER 3 Fabrication 3.1 PREPARATI
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Figure 3.1 Alternative designs for
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Figure 3.2 Thread insert. a coil-sp
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3.3 ARC WELDING 3.3.1 Use of arc we
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adjusted. The technique is claimed
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For welds of minimum or fatigue qua
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Figure 3.5 Friction-stir welding: s
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are, and the designer/fabricator mu
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cartridge, and mixing takes place a
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3.7.4 Painting Alloys having durabi
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Where a range is given, as for the
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will be only slightly above that fo
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heating the metal to a temperature
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Table 4.4 Characteristics of differ
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softening in the heat-affected zone
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60 alloys, are: BSEN.485 plate and
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Firure 4.3 Nominal composition and
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popular alloys in the series are: 6
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Figure 4.6 Variation of tensile str
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undercarriages of aircraft. They ar
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Figure 4.11 Minimum stress-strain c
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AC.51400 This is another non-heat-t
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times that of the actual pits) prod
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The severity of bimetallic corrosio
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Nominal loading. Nominal loads are
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2. Material factor (� m ). In the
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design does not, because stress at
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Table 5.2 Summary of limiting stres
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Figure 5.4 Plastic strain at workin
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example, a reduced value might be t
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The parameter � depends purely on
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CHAPTER 6 Heat-affected zone soften
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area of softening. With 7xxx-type m
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Figure 6.3 Typical hardness plots a
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6.4 SEVERITY OF HAZ SOFTENING 6.4.1
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Figure 6.6 Categories of welded joi
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Figure 6.10 One-inch rule, extent o
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e allowed for in design by replacin
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Figure 6.13 Predicted area (A z ) o
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Figure 6.15 Overlapping HAZs. nomin
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In determining A zp , an appropriat
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failure plane in the HAZ, close to
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With MIG welding, an electrode-posi
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CHAPTER 7 Plate elements in compres
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(a) Compression member elements The
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Table 7.1 Classification of element
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Figure 7.4 Slender internal element
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Figure 7.7 shows curves of � ° p
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(7.9a) (7.9b) The strain gradient c
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(through the centroid) for ß S . F
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Figure 7.13 Outstands under strain-
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Figure 7.15 Reinforced elements. Th
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Figure 7.18 Stiffener location for
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Figure 7.20 Slender reinforced inte
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CHAPTER 8 Beams 8.1 GENERAL APPROAC
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8.2.2 Section classification The di
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that for the gross section. It woul
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the usual manner. Line 1 in the fig
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1. Fully compact sections. The limi
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Figure 8.8 Transverse and longitudi
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8.3.4 Shear resistance of bars and
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Figure 8.12 Tension-field action. i
Page 181 and 182: Figure 8.14 Moment/shear interactio
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Page 185 and 186: where a is the stiffener spacing an
Page 187 and 188: plates (if fitted), p v =limiting m
Page 189 and 190: ending moment diagram. Two cases ar
Page 191 and 192: Figure 8.23 Sections covered in Tab
Page 193 and 194: where: I yy , I vv =inertia about m
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Page 197 and 198: Figure 8.26 Components of deflectio
Page 199 and 200: 9.1.2 Classification of the cross-s
Page 201 and 202: hole. Alternatively, it might fail
Page 203 and 204: Figure 9.2 Limiting stress p b for
Page 205 and 206: The determination of l involves a c
Page 207 and 208: Figure 9.6 Monosymmetric section. I
Page 209 and 210: Figure 9.9 Limiting stress p b for
Page 211 and 212: where s=� s /� t s =slenderness
Page 213 and 214: Figure 9.11 Type-R sections covered
Page 215 and 216: Figure 9.14 Four standardized profi
Page 217 and 218: 9.7.2 Secondary bending in trusses
Page 219 and 220: Table 9.5 Necessary checks for memb
Page 221 and 222: Figure 9.18 Axial load with biaxial
Page 223 and 224: 1. Tension members. The localized f
Page 225 and 226: Figure 10.1 Symmetric plastic bendi
Page 227 and 228: We now turn to monosymmetric sectio
Page 229 and 230: distance of its centroid from the n
Page 231: Figure 10.6 Elements of sections. I
Page 235 and 236: Usually the conditions are such as
Page 237 and 238: Table 10.2 Torsion constant. Factor
Page 239 and 240: Figure 10.12 Warping. Conventional
Page 241 and 242: where b, t=element width and thickn
Page 243 and 244: 10.5.3 Evaluation of warping When t
Page 245 and 246: For sections where the position of
Page 247 and 248: (10.31) where: e=distance that S li
Page 249 and 250: 10.5.9 Asymmetric sections Before s
Page 251 and 252: CHAPTER 11 Joints This chapter cons
Page 253 and 254: the use of limiting stresses taken
Page 255 and 256: and the summation is made for all t
Page 257 and 258: Figure 11.3 Interaction diagram for
Page 259 and 260: k in order to give a fair compariso
Page 261 and 262: 3. The design is satisfactory if fo
Page 263 and 264: When the method of surface preparat
Page 265 and 266: 11.3.3 Weld force arising In many c
Page 267 and 268: Table 11.6 Limiting stress p w (N/m
Page 269 and 270: where p a =limiting stress for unwe
Page 271 and 272: Figure 11.11 Interaction diagram fo
Page 273 and 274: Manufacturers of structural adhesiv
Page 275 and 276: 11.4.6 Creep Shear strength figures
Page 277 and 278: Figure 11.15 Effect of glue-line th
Page 279 and 280: Table 11.7 and Figure 11.17 provide
Page 281 and 282: 11.4.11 Resistance calculations for
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high value reflects the various unc
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therefore usually presented in term
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For example: The loading spectrum i
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act on the structure. However, BS.8
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Figure 12.4 Crack propagation: (a)
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12.5 CLASSIFICATION OF DETAILS 12.5
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i.e. a joint extending in the same
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when the design life is low or when
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Methods (2) and (3) are difficult t
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it reverts to line 1. The slope s o
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Aluminium Design and Construction John Dwight

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