Manufacturing-induced stresses approach 30% of yield strength. Mitigation methods:
Heat treatment:
Stress relieving at 600°C for 1hr/25mm thickness
Normalizing at 900°C for heavy sections
Mechanical stress relief:
Vibratory treatment (98% effective)
Proof loading to 110% service stress
Design compensation:
Increased safety factors
Avoidance of stress concentrators.
What connection types optimize constructability?
Modern connection technologies:
Bolted end plates:
Grade 8.8 or 10.9 bolts
Slip-critical (Class A) or bearing-type
Typical spacing: 3d (bolt diameter)
Welded moment connections:
Complete joint penetration (CJP) welds
Weld access holes per AWS D1.1
Hybrid systems:
Shop-welded, field-bolted
Reduced erection time by 40%
How does rolling direction affect mechanical properties?
Anisotropy creates 10-15% variation:
Longitudinal (rolling direction):
Highest toughness (50J Charpy)
Ductility: 22% elongation
Transverse:
Reduced impact strength (35J)
15% lower fatigue life
Critical applications (e.g., seismic zones) require:
Through-thickness testing (Z35 quality)
Controlled rolling practices
What standards govern international trade?
Key specifications:
Metric dimensions:
EN 10025 (Europe)
JIS G3101 (Japan)
GB/T 11263 (China)
Imperial sizes:
ASTM A6/A36 (USA)
BS 4-1 (UK)
Special applications:
EN 10210 for hollow sections
API 2H for offshore structures
How are camber and sweep controlled?
Fabrication tolerances:
Camber (vertical curve): L/1000 max
Sweep (horizontal curve): L/1000 max
Correction methods:
Heat straightening:
Localized heating to 650°C
80% effectiveness
Mechanical pressing:
2000-ton hydraulic rams
For sections <15m
