Remediation of an historic bridge in the capital city of the Philippines posed a series of technical challenges for Freyssinet and its joint venture partners in this innovative rehabilitation project.

Bids were initially invited for full replacement of the structure, but our alternative proposal to restore and strengthen the bridge found favour due to its significant cost and time savings.

  • Name of the owner
    Department of Public Works & Highways
  • Client’s representative
    Ernesto S De Castro & Associates / JF Cancio Joint Venture
  • Delivery date of the project
    July 2015
  • Partners of the project
    Main contractor: JV Frey-Fil Corporation, EEI Corporation & Freyssinet
    Detailed design: Freyssinet Technical Department
    Local consulting engineer: Angel Lazaro & Associates International
Ayala bridge from the road

Historical steel bridge upgrading

The two-span truss bridge carries one of the city’s main road arteries over the Pasig River, itself an important transport route for petrochemical tankers and other vessels. Dating from the 1950s, the Ayala Bridge was suffering from corrosion to its steel structure and bearings, and it did not meet modern highway and seismic standards, making it vulnerable to earthquakes. Ships could only pass under the bridge at low tide, so clearance was to be increased by 700 mm to improve access. This was accomplished by raising the entire bridge with strand jacks – a first for the Philippines.

Alternative proposal reducing time and cost

The replacement proposal anticipated closing down access for up to two years, in order to demolish the old structure and build a new one in its very congested city-centre location. By contrast, only a couple of months’ full closure were necessary to repair and upgrade the old bridge – and at just 40% of the cost of replacement.

However such an intervention increased the technical demands significantly. Extensive investigation and analysis was necessary before construction began, to establish the condition of the structure and assist in design of bespoke remedial works. The nature of the project also demanded an agile project team, able to respond quickly to whatever circumstances were uncovered as work progressed.

Ayala bridge 3D
Seismic protection on Ayala bridge

Seismic protection

For the horizontal transverse earthquake behaviour, 12 ISOSISM high-damping rubber bearings coupled with five ISOSISM hydraulic fluid dampers were installed at the central pier and abutments in order to dissipate seismic energy and protect the existing substructure. Three sacrificial shear keys were added to the substructure to restrain transverse movement under typhoon conditions.

Changing behaviour

One major adaptation of this innovative rehabilitation project was the decision to change the articulation of the structure to reduce the potential loads on the foundations, enabling the existing piles and pile caps to be retained and eliminating a significant amount of work. The decks of the two truss spans were made continuous at the central pier by stringers and reinforcement in a concrete beam and deck slab, and three new 25 m-long concrete ground beams at each abutment tied the bridge back to bored piles. This arrangement was designed to accommodate horizontal longitudinal loads in the event of an earthquake.

  • 700
    Additional vertical clearance created (mm)
  • 20,000
    Number of vehicles using the bridge everyday

Additional capacity

To comply with live loads specified in modern AASHTO codes, the capacity of the steel spans was increased by the use of post-tensioning cables threaded through the closed box bottom chords and T- shaped steel beams welded to the top chords. Bespoke strengthening works to other joints and riveted connections were also developed.

A closure of just 82 calendar days was necessary for those activities that could not be carried out with traffic on the bridge.

Scaffolding on Ayala bridge

You have a project?

Our local experts will help you achieve your project thanks to our large range of solutions.
Find your local contact

R&D and Innovation

Our innovation strategy reflects our ambition: to provide solutions that meet our customers’ needs, and which are also more sustainable and environmentally friendly.
Discover our R&D vision