Bridge Strengthening and Rehabilitation: An Overview for Asset Owners

Bangladesh's river-crossed landscape depends on thousands of bridges and culverts, many of them decades old. Traffic is heavier than these structures were designed for, rivers shift and scour their foundations, and materials age. Replacing every older bridge is neither affordable nor necessary — careful assessment and strengthening can often extend service life safely.

Common problems in older bridges

• Increased loads — heavier trucks and higher traffic volumes than the original design assumed
• Scour — river flow eroding soil around piers and abutments, especially during monsoon floods
• Corrosion — of reinforcement, prestressing steel and steel girders
• Cracking — in deck slabs, girders and piers
• Bearing and joint failures — seized bearings and leaking expansion joints causing secondary damage
• Impact damage — from vehicles and river vessels

Assessment

Bridge assessment combines a detailed visual inspection, material testing, measurement of deformations and, where needed, load testing, followed by structural analysis for current traffic loads. Underwater inspection of foundations is particularly important where scour is suspected.

Strengthening techniques

Deck and girders

• CFRP plates or sheets bonded to the underside of girders and slabs to increase flexural capacity, or wrapped around girders for shear
• Steel plate bonding for flexural strengthening
• External post-tensioning to reduce stresses and close cracks
• Deck overlays that add structural depth and protect against wear

Piers and columns

• RC or steel jacketing to increase axial and lateral capacity
• CFRP wrapping for confinement and seismic ductility

Foundations

• Scour protection with riprap, gabions or concrete aprons
• Additional piles or enlarged pile caps where capacity is insufficient

Bearings and joints

• Replacement of damaged bearings using temporary jacking
• Renewal of expansion joints and drainage to stop water reaching the substructure

Working under traffic

Many bridges cannot be closed. Strengthening schemes are therefore planned in phases with traffic management, and techniques such as CFRP are often preferred because they add little weight and can be installed quickly.

A lifecycle view

Regular inspection, early repair and planned strengthening are far more economical than emergency closures. A prioritised programme — based on condition, importance and risk — helps asset owners spend limited budgets where they matter most.

Bridges and civil infrastructure are part of our structural retrofitting and strengthening service. Contact our engineers to discuss an assessment.