Emerging Timber Bridge Program to São Paulo State: A Five-Year Report

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1 May 2011, Volume 5, No. 5 (Serial No. 42), pp Journal of Civil Engineering and Architecture, ISSN , USA Emerging Timber Bridge Program to São Paulo State: A Five-Year Report Carlito Carlil Junior and Julio Cesar Molina Department of Structural Engineering, São Carlos School of Engineering, University of São Paulo, Brazil Abstract: The Emerging Timber Bridge Program to São Paulo state (ETBPSP) was started in 2001 with the main objective of research and development of new technologies for timber bridge construction. After five years of this program eleven demonstration timber bridges were constructed in the State of São Paulo, whereas eight composite timber/concrete bridges, one log timber girder bridge with transversal sawn deck, one transversal lumber prestressed timber bridge and one transversal cellular plywood box prestressed bridge. As a final objective is the divulgation of the constructive and structural systems in extension courses to municipal engineers and in a complete publication of timber bridges project plans with the different structural and constructional systems. This paper describes the goals of the MTBPSP, the accomplishments of the program in the first five years, the information sheet of the bridges and outlines some obstacles and opportunities. Key words: Bridge decks, Brazil, testing, timber-concrete, timber. 1. Introduction Most timber bridges in Brazil are not designed and constructed by technicals and constructors specialized in timber structures. This laid to expensive, unsafe and low durability timber bridges [1]. The actual state of degradation of these bridges shows a very negative picture of the use of wood as a structural material. Therefore it is very important to develop wood technology in the construction and rehabilitation of timber bridges in county and state roads. If one considers that the São Paulo state road system has 220,000 km of vicinal roads and considers the existence of 0.5% of bridges, this means 2200 km of bridges [2]. If one still considers the medium span of 10 meters we will have 111,000 bridges. Recent research made in LaMEM in an expressive number of counties of the state showed that at each bridges and pedestrian bridges, 30% must be Corresponding author: Carlito Carlil Junior, professor, research fields: wood bridges, wood structures and composite structures wood-concrete. calil@sc.usp.br. reconstructed or rehabilitate. In São Paulo State doesn t have native wood species and the use of reforestation species is a natural solution. In the actual reforestation areas, pines and eucalyptus are the most important to use in civil constructions and its availability are very good. The structural pieces are normally used in log or sawn beams with the application of preservative treatment. So, the development of new technologies to timber bridge constructions, the analysis and improvement of the actual structural and constructive systems, the adaptation of existent international technologies to national conditions are objectives here with the aim to have the technology to construct safe timber bridges, with simple and modern constructive techniques, with good durability like others structural materials and with a competitive cost. 2. Methodology of the Research After five years of this program eleven demonstration timber bridges were constructed in the State of São Paulo, whereas eight composite timber/concrete bridges, one log timber girder bridge with transversal sawn deck, one transversal lumber

2 460 Emerging timber bridge program to São Paulo State: a five-year report prestressed timber bridge and one transversal cellular plywood box prestressed bridge [3]. 2.1 Characteristic of the Monjolinho Bridge (Fig. 1) Structure/Design Type: Vehicular Bridge/stress-laminated sawn lumber Location: São Carlos SP Owner: São Carlos Municipality Length: 8 m Number os Spans/Skew: 1/5.0 Primary Wood Species: Citriodora Eucalyptus Connection: dywidag bars 2.2 Characteristic of the Paracatu Bridge (Fig. 2) Location: Paracatu-MG Owner: Uberaba University Length: ( ) m Number os Spans/Skew: 2/0.0 Primary Wood Species: Citriodora Eucalyptus Fundation: Concrete Connection: X glued steel bars 2.3 Characteristic of the Capela Bridge (Fig. 3) Length: 7 m Width: 5 m Connection: vertical steel bars of 19 mm diameter 2.4 Characteristic of the Caminhos do Mar Bridge (Fig. 4) Location: SP148 KM 5-Santos-SP Owner: DERSA-SP Length: 23 m (6m+12m+5m) m Width: 8 m Number of Spans/Skew: 3/15.0 Concrete: fck: 25 MPa Connection: X glued steel bars Fig. 1 Monjolinho Bridge. Fig. 2 Paracatu Bridge.

3 Emerging timber bridge program to São Paulo State: a five-year report 461 Fig. 3 Capela Bridge. Length: 7 m Design Live Load: 30 Connection: X steel bars of 19 mm diameter 2.7 Characteristic of the Itibiruna Bridge (Fig. 7) Fig. 4 Caminhos do Mar Bridge. 2.5 Characteristic of the Floresta Bridge (Fig. 5) Log Bridge Length: 6 m Width: 5 m Design Live Load: 30 Deck: tranversal planks with screw connections 2.6 Characteristic of the Florestinha Bridge (Fig. 6) Composed Timber/Concrete Length: 6 m Design Live Load: 30 Connection: 45 degrees inclined tension steel bars of 12.5 mm diameter 2.8 Characteristic of the Paredão Vermelho Bridge (Fig. 8) Length: 10 m Width: 5 m Connection: X steel bars of 12.5 mm diameter

4 462 Emerging timber bridge program to São Paulo State: a five-year report 2.9 Characteristic of the Campus II USP Bridge (Fig. 9) Fig. 5 Floresta Bridge. Composed Timber/Concrete Location: São Carlos-SP Owner: USP-EESC Length: 12 m Width: 10 m Number os Spans/Skew: 1/25 Concrete: fck: 25 MPa Foundation: Concrete Blocks Connection: X steel bars of 12.5 mm diameter 2.10 Characteristic of the Campus II USP Bridge (Fig. 10) Fig. 6 Florestinha Bridge. Fig. 7 Itibiruna Bridge. Fig. 8 Paredão Vermelho Bridge. Location: São Carlos-SP Owner: USP-EESC Length: 12 m Width: 10 m Number os Spans/Skew: 1/25 Concrete: fck: 25 MPa Foundation: Concrete Blocks Connection: X steel bars of 12.5 mm diameter 2.11 Characteristic of the Campus II USP Bridge (Fig. 11) Stress-laminated Cellular Plywood Box Location: São Carlos-SP Owner: USP-EESC Length: 12 m Width: 10 m Number os Spans/Skew: 1/25

5 Emerging timber bridge program to São Paulo State: a five-year report 463 Primary Wood Species: Plywood and Cupiuba Sawn Lumber Foundation: Timber Piles Stress System: dywidag bars 15 mm diameter Fig. 9 Campus II USP Bridge Analytical Evaluation Predicted deflections based on analytical modeling are also determined for comparison with static load test results. An orthotropic plate computer program adapted for highway bridges was used to simulate the deck behavior of each bridge under actual test truck axle loads. This software named Orthotropic Timber Bridge (OTB) analyze five types of plates: composed timber-concrete plate; stress laminated sawn lumber plate, stress laminated T section plate, stress laminated cellular box plate and stress laminated truss plate. Fig. 4 shows a theoretical-otb and experimental results comparison Load Test Behavior Fig. 10 Fig. 11 Campus II USP Bridge. Campus II USP Bridge. Static-load tests are conducted during construction and after some time period to determine the response of the bridges to full truck loading. Each test consists of positioning a fully loaded truck on the bridge deck an measuring the resulting deflections at a series of transverse locations at midspan. Measurements of bridge deflections are taken prior to testing (unloaded) for each load position (loaded), and at the conclusion of testing (unloaded). In addition, analytical assessments are conducted to determine the theoretical bridge response. The test vehicle consists of a fully loaded, three axle dump truck with a gross vehicle weight of about 25 ton, as shown in Fig. 12. The vehicle is positioned longitudinally on the bridge so that the two rear axles are centered at midspan. Transversely, the vehicle is placed for three load positions, as shown in Fig. 13. Measurements of the bridge deflection from an unloaded to loaded condition are obtained by placing a calibrated rule on the deck underside and reading values with a surveyor s level.

6 464 Emerging timber bridge program to São Paulo State: a five-year report 3. Research Results and Discussion The experimental and theoretical analysis results of the measured deflections with vehicle centered showed good agreement as we can observe in Fig. 14. Also, in 2008, visual inspections of the bridges confirmed the good bridge performance. Fig. 12 Load test truck configuration. Fig. 15 Comparison of the measured deflections Vehicle centered. 4. Conclusions The preliminary results of the emerging program are the bridge construction, five courses of design and construction of timber bridges for engineers of the Department of Roads of São Paulo State and for Construction Engineers of São Paulo Provinces, four class note publications for the courses and the software OTB (Orthotropic Timber Bridge) for the design of these kinds of timber bridges. The final report is the Manual for Timber Bridge Design and Construction. Fig. 13 Load test transverse load positions. Acknowledgments The author thanks the financial support of the Foundation of Support of Research of São Paulo State FAPESP. References Fig. 14 Transverse deflection points at the bridge midspan. [1] C. Jr. Calil, Long term field performance of seven stress laminated deck hardwood wood bridges in Pennsylvania, Relatório de bolsa de pós-doutorado no exterior: FAPESP, São Carlos, 2001, p [2] C. Jr. Calil, Emerging Timber Bridge Program to São Paulo State, Report No. 1 and 2, Thematic Project in Development in the Laboratory of Wood and Timber Structures, Department of Structures, School of Engineering, São Paulo University, 2002, p [3] C. Jr. Calil et al., Design and construction of timber bridges-class notes, course of University Extension LaMEM/SET/EESC/USP, May , pp. 69, 78, 78, 98, 117.