US-Japan Workshop on Life Cycle Assessment of Sustainable Infrastructure Materials Sapporo, Japan, October 21-22, 2009 Optimizing LCC for Pier Bridges using FRP Members Professor Seishi Yamada Chairman of Faculty Meeting, Head of Dept, Dept of Civil Engrg, Toyohashi University of Technology, Japan
Task Committees for FRP Bridges in JSCE • Task Committee for Research on FRP Bridges (2000-2) – Chair: Prof. Ohshima, Kitami Univ. of Technology • Task Committee for Research on FRP Bridges (2002-4) – Chair: Prof. Maeda, Tokyo Metropolitan Univ. • Task Committee for Design of FRP Bridges (2004-6) – Chair: Prof. Yamada, Toyohashi Univ. of Technology • Task Committee for FRP Hybrid Bridge (2006-9) – Chair: Prof. Yamada, Toyohashi Univ. of Technology
US-Japan Workshop on Life Cycle Assessment of Sustainable Infrastructure Materials Sapporo, Japan, October 21-22, 2009 Optimizing LCC for Pier Bridges using FRP Members Contents 1. Introduction 2. Situation of Steel Pier Bridges 3. Cost Analyses for Pier Bridges 3.1 Initial Construction Cost 3.2 Comparison of Costs Considering LCC 4. Conclusions Appendix: FRP Footbridges in Japan
Fiber reinforced polymer (FRP) is anticipated for the use as innovative structural members that replace the conventional materials, and in the last decade in USA, many applications to the structural, girder, slab and truss members have been presented. Also in Japan, a several FRP foot bridges have recently constructed based upon various energetic research developments. To infiltrate FRP footbridges into Japan, JSCE has engaged to make FRP footbridge design guidelines. Meanwhile, it would be also important to find the new places to apply FRP structural members and JSCE has also targeted the investigation of the application to PIER bridges.
It would be well known that pier bridges connect between wharf and pontoon and is generally located on hard salt environment. The pier bridges vary from
Large pier bridge which is able to pass a car Small pier bridge which passes people mainly
Using the construction details including the costs of recently erected footbridges in Japan (see Appendix), this paper estimates the initial construction cost and life cycle cost (LCC) of a pier bridge through the analyses of maintenances and repaints, and discusses on the applicability of FRP to pier bridges.
2. Situation of Steel Pier Bridges Currently, almost pier bridges are of steel, therefore, a lot of administrators of pier bridges are now faced with big problems on the durability and maintenance for steel members due to the use under the hard environment. Main deterioration factors are corrosion due to splash salt, and fatigue due to waves in the storm and enforcement deflection by landing ship.
Corrosion due to splash salt Storm Wave or Landing Fatigue due to waves in the storm
Steel pier bridges in Hiroshima, Japan Investigated by the author, 2007
It is much difficult for the administrator to inspect and sustain his pier bridges as offshore structures. He tends to overlook and leave progress of corrosion because the speed of corrosion under the deck is quicker than one over the deck. Also, the maintenance requires hard working because the workers need a boat for the inspection and painting.
The other point of view is its ability of rehabilitation after damage due to a heavy storm; pier bridges drop from pontoon and sink into the sea, so they would be required to be taken to salvage and to be recovered after storming as soon as possible. In order to solve these problems, the FRP pier bridges having various advantages (hard corrosion, hard fatigue, light weight and short construction period) are now anticipated strongly by many administrators in Japan.
3 COST ANALYSES FOR PIER BRIDGES 3.1 Initial Construction Cost We have four FRP footbridges whose detailed data were already presented in Japan. All are of girder or truss types, so these two types are adopted in this study. According to domestic achievement, it seems that length of span about girder and truss limited 20 meters due to serious specification of deflection in Japanese conventional design guidelines for steel bridges. The obtained analytical results are represented in Appendix in which each completion time, weight, structure cost, maintenance cost are listed, consequently they can be easy compared together.
Through the preliminary design for steel as well as FRP pier bridges of above bridge types, their initial construction costs were tried to estimate. On the pier bridges of this study, the effective width = 2m, the length of span = 5m, 10m, 15m and 20m. Referring to the Japanese Standard for Vertical Cross Footbridges 1979, 2 the design live load = 3.5 kN/m the limit of deflection = L /600 for steel pier bridges = L /400 for FRP pier bridges ( L = length of span)
For a STEEL pier bridge, its weight in ton force unit (9.8kN) was computed as referring the design data of selected existing steel pier bridges in Japanese Design Data Book, then its computed weight was multiplied with the following constant; 1.0 million JPY/tonf for the girder type or 1.2 million JPY/tonf for the truss type.
For a FRP pier bridge, its floor space in square meter was computed then its computed weight was multiplied with the constant; 0.45 – 0.47 million JPY/m 2 for the girder type or 0.32 – 0.35 million JPY/m 2 for the truss type.
Initial Construction Cost (Effective width=2m) 25 Steel Gider Cost(million JPY） Steel Truss 20 FRP Truss FRP Girder 15 10 5 0 5 10 15 20 Length of Span (m) Examples: Initial construction costs for 2m width. The cost performances: the parameter = span L The FRP girder pier bridge is the most expensive. The cost of FRP truss pier bridges is almost the same price as that of steel pier bridges.
3.2 Comparison of Costs Considering LCC Generally, steel pier bridges require the periodic repaint due to preventing from corrosion. Thus, the interval of repaint for steel pier bridges is 10 years from actual achievement. The unit cost of paint for steel pier bridge is 9,000 JPY/m 2 as polyurethane paint with epoxy on sand blasted base. The interval of repaint for FRP pier bridges is assumed to be 15 years because FRP did not corrode but needs to keep surface for preserving aesthetic view against ultraviolet ray degradation. The unit cost of paint for FRP pier bridge with effective width 2m was estimated to be 0.6 million JPY/m from the domestic achievement, e.g. acrylic urethane paint or fluorine paint.
The FRP truss pier bridges are superior to the steel Results for LCC pier bridges at 20 years after completion 1 0 . 0 S t e e l G i r d e r ) Y S t e e l T r u s s P J 7 . 5 F R P T r u s s n F R P G i r d e r o i l 5 . 0 l i m ( t 2 . 5 s o C 0 . 0 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 Y e a r Fig.7 Life Cycle Cost for the case of “Length of Span = 5m”
The FRP truss pier bridges are superior to the steel pier bridges at 20 years after completion 1 5 . 0 ) Y 1 2 . 5 P J 1 0 . 0 n o i l 7 . 5 l i S t e e l G i r d e r m 5 . 0 ( S t e e l T r u s s t s F R P T r u s s 2 . 5 o C F R P G i r d e r 0 . 0 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 Y e a r Fig.8 Life Cycle Cost for the case of “Length of Span = 10m”
The FRP truss pier bridges are superior to the steel pier bridges at 20 years after completion 2 5 . 0 ) Y 2 0 . 0 P J n o 1 5 . 0 i l l i 1 0 . 0 S t e e l G i r d e r m ( S t e e l T r u s s t s 5 . 0 F R P T r u s s o C F R P G i r d e r 0 . 0 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 Y e a r Fig.9 Life Cycle Cost for the case of “Length of Span = 15m”
The FRP truss pier bridges are superior to the steel The cost of FRP girder pier bridges is also shown to be pier bridges at 20 years after completion smaller at 30 years or 40 years than that of the steel truss pier bridges. 3 5 . 0 ) 3 0 . 0 Y P J 2 5 . 0 n o 2 0 . 0 i l l 1 5 . 0 i S t e e l G i r d e r m ( 1 0 . 0 S t e e l T r u s s t F R P T r u s s s 5 . 0 o F R P G i r d e r C 0 . 0 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 Y e a r Fig.10 Life Cycle Cost for the case of “Length of Span = 20m”
CONCLUSIONS Studying on the feasibility of FRP pier footbridges, it has been interpreted that the LCC for FRP pier bridges is expected to be smaller than that for conventional steel pier bridges. It would be surmised that optimizing span length of the FRP pier footbridges is approximately from 10m to 20m under the cost data of recently constructed four FRP footbridges in Japan and the truss type is the better choice rather than the girder type for FRP pier footbridges.
initial cost conventional design Neglect of Greenhouse Cost Reduction Index Emission Effects IC C > IC R LCC LCO 2 e Life Cycle Environmental Friendly Index Quality Index IE C > IE R IQ C > IQ R strength, ductility, beauty, appropriate design comfort ability New Concept of Performance Based Environmental Design for Infrastructures by Seishi Yamada 2009
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