Page 33 - Bridge and Highway Structure Rehabilitation and Repair

8 SECTION 1 ADMINISTRATIVE ISSUES

Figure 1.2 The inevitable cycle in the life of a bridge.

• Improving soil conditions
• Use of standard geometry, alignment, and profi le
• Vertical and horizontal clearances
• Constructability
• Use of alternates analysis
• Aesthetic requirements
• Environmental permits
• Public involvement
• New technology and innovative methods
• Future maintenance and inspection access
• Development of rehabilitation and replacement schemes
• Performing value engineering.

1.3.2 Types of Materials for Bridge Girders
1. The following types of materials are used for bridge girders:
Type 1–Timber: Solid sawn, glulam.
Type 2–Concrete: Made of cast in place or precast construction:
• Slab bridge, T-beam, reinforced and highly redundant prestressed concrete AASHTO
I-girders and box girders, and segmental beams
• Plain concrete or reinforced concrete
• Prestressed concrete, post-tensioned or pre-tensioned.
Type 3–Steel: Rolled steel and fabricated plate girders, multi-girder and through bridges,
box girders, trusses, arches, and rigid frames.
• Old bridges were built with mild steel used at the time of construction. Commonly used
grades of steel were A7, A373, A36, A440, A441, A572, and A709. Currently grades 50,
50W, 70W (and 100W) are being used.