Site: Public Works Research Institute Test Facility
Tsukuba City
Ibaraki, Japan
Date Visited: October 1996
Hosts: U. Nishikawa, Head Bridge Division, PWRI
Masayuki Kanda, Chief Research Engineer, PWRI
Kenichi Uchida, Research Engineer, PWRI
Summary: The test site contains an all composite cable-stay bridge built using pultruded profiles and an outdoor weathering/aging facility.


The test facility, which is in the open, consists of two sections:

  1. An all composite bridge completed in March 1996
  2. Weathering stations for various materials and components

The pedestrian cable stayed bridge (completed in March 1996) is completely fabricated from polymer composites. The deck, cross girder, rails and stairs are fabricated from pultruded glass fiber reinforced composites (Fig. B.24), and all three types of cables used are carbon fiber reinforced.

One cable type each was produced by Mitsubishi Chemical (Leadline), Tokyo Rope (CFCC) and one other manufacturer. The bridge has a total length of 20 m, with the central span being 11 m in length. Six cables from each tower are connected to the cross girders, which are externally reinforced by carbon fabric. The cables support the deck (Fig. B.25), and go through the pultruded towers before being anchored at the top.

Fig. B.24. Overall view of the all-composite pedestrian test bridge.

Fig. B.25. Detail showing bolted connections between the deck, girders and supporting towers.

The deck is connected to the cross girders using 16 mm diameter fiber reinforced composite bolts, which are also used to assemble the tower assembly. Four towers, each 6 m high and weighing 140 kg, have been fabricated out of pultruded profiles that are externally reinforced with additional glass fabric (Fig. B.26). Each deck slab panel weighs 150 kg (in order to allow manual assembly) and is 8 m x 0.65 m. The overall weight of the bridge (including stairs and hand rails) is 4.4 tons. The design live load was 350 kg/m2, which when compared to the dead load of 110 kg/m2 results in a DL/LL ratio of 0.3. All the pultruded sections are hollow.

The bridge serves as a technology demonstrator and as a test bed for real time monitoring under natural environmental conditions. Strain gages were attached to the cables only and were reportedly connected to a monitoring device at intervals. The bridge is built on conventional reinforced concrete foundations and anchored with steel anchor bolts. The bridge was successfully load tested upon completion and will be tested at intervals to determine effects of aging and environmental degradation.

The second part of the test site consists of a large number of weathering stations that include test specimens of various coatings applied to metals, paints and coatings for concrete structures, composites bonded to flat concrete blocks (with and without coatings), composite fabric externally reinforced "T" beams, epoxy coated rebar, tendon sheaths, hollow pultruded profiles being tested for aging and creep, and materials test specimens. The overall objective is to gather as much real time data on weathering and environmental durability as possible in a realistic environment. Some specimens were provided to PWRI directly by industry. Others were fabricated/installed by PWRI scientists themselves. All testing is conducted by PWRI personnel.

Fig. B.26. Detail showing additional fabric reinforcement on the pultruded tower (similar reinforcement is also placed on girders).

Fig. B.27 Detail showing connection and top anchorage of cables.

Fig. B.28. Details of stress block and anchorage on the cross beam.

Fig. B.29. Pultruded specimens under load (testing for creep and weathering action).

Published: October 1998; WTEC Hyper-Librarian