This thesis examines the development of a superstructure for a slab-on-girder wood-concrete composite highway bridge. Wood-concrete composite bridges have existed since the 1930's. Historically, they have been limited to spans of less than 10 m. Renewed research interest over the past two decades has shown great potential for longer span capabilities. Through composite action and suitable detailing, improvements in strength, stiffness, and durability can be achieved versus conventional wood bridges. The bridge makes use of a slender ultra-high performance fibre-reinforced concrete (UHPFRC) deck made partially-composite in longitudinal bending with glued-laminated wood girders. Longitudinal external unbonded post-tensioning is utilized to increase span capabilities. Prefabrication using double-T modules minimizes the need for cast-in-place concrete on-site. Durability is realized through the highly impermeable deck slab that protects the girders from moisture. Results show that the system can span up to 30 m while achieving span-to-depth ratios equivalent or better than competing slab-on-girder bridges.
An innovative concept for a modular timber concrete composite system for short span highway bridges has been designed and key components experimentally validated. The proposed system consists of a Ultra-High Performance Fibre Reinforced Concrete(UHPFRC) deck and glue-laminated timer (glulam) girders linked to act compositely together by reinforcing steel bar shear connectors. This composite system has light, stable modules that can be rapidly constructed on site with less special equipment. Simple design checks indicate that the concept satisfies all serviceability limit state(SLS) and ultimate limit state(ULS) requirements of the Canadian Highway Bridge Design Code. Pull-out tests characterized the embedment lengths of 20M steel bar connectors to be 10 bar-diameters in UHPFRC. Push-off tests determined the embedment lengths of the same bars to be 30 bar-diameters glued into the timber girders. The slip modulus of the connectors is determined to be 67 kN/mm. The stiffness of the crosswise self-tapping screw connectors were tested and found to be structurally insignificant in this application. The excellent tensile and cracking properties of the reinforced UHPFRC deck was experimentally verified. A small amount of reinforcement would further improve the ductility of the UPHFRC deck system.
In the last 15 years timber-concrete composite (TCC) systems have gained market share around the world. To facilitate acceptance of this construction method and to set basis for building TCC bridges in the Province of Quebec, the authors conducted a test program on TCC beams with continuous shear connectors. It included push-out...
The performance of timber-concrete composite bridge constructions crucially depends on the design of the joint between concrete deck and timber main girders. In research studies at the Bauhaus-University Weimar, innovative joining techniques based on grouting with highly-filled, tolerance-compensating polymer glue mortars have been developed to improve the shear capacity of this joint significantly. By applying a thin layer of polymer mortar on the top of the wooden main girder a continuous, slip-free connection to the timber can be realized. This layer can be utilized for the embedding of steel plates with welded-on shear studs (stud connectors), so that the joint to the concrete side is ensured by a standardised connection. The steel plates are rigidly anchored in the polymer mortar by adhesive bond and form closure. As an alternative, a slip-free grout-glued connection between concrete and timber can be realized by the glue mortar itself, so that also a continuous connection to the concrete is accessible, whereby manufacturing tolerances can easily be compensated due to the high degree of mineral filling of the polymer mortar. The paper focuses on experimental results of shear and bending tests for the new composite joint configurations.
IOP Conference Series: Materials Science and Engineering
The timber bridge design although economical, often has difficulty producing enough rigidity so that a solution is needed to solve it. The use of CFRP (Carbon Fiber Reinforced Polymer) as a reinforcement of structural elements if properly designed and implemented can produce an effective and efficient composite structure. The experimental study aims to analyse the strength, stiffness and ductility of flexural strengthening composite bridge glued laminated timber beams-concrete plates using CFRP layers. The dimensions of the composite glued laminated timber beams 100/180 mm and concrete plate 75/300 mm with a length of 2,480 mm. The number of specimens is 3 composite glued laminated timber beams-concrete plate consisting of 1 test beam without CFRP reinforcement, 1 test beam with one layer CFRP reinforcement, and 1 test beam with three layer CFRP reinforcement. Experimental testing of flexural loads is done with two load points where each load is placed at 1/3 span length. The test results show that the strength of composite laminated timber beams glued - concrete plates BN; BL-1; BL-2 in a row 81.32; 82.82; 82.69 kN/mm; stiffness in a row 7.51; 8.22; 6.32 kN/mm and successive ductility of 16.67; 28.83; 20.21.
Timber-concrete-composite (TCC) systems have increasingly been used in recent decades. One of the main reasons for this development is related to applications that could not be built with timber alone, but that become possible with a TCC solution. This paper first gives a short overview of the use of TCCs, the relevant regulatory framework, and then presents several case studies of TCC applications. The perspectives and examples are from Europe, North America and Oceania to give a worldwide perspective from regions where TCC systems are being used. The structural systems presented in the case studies include bridges and floors in public buildings. For each project, details of the application are presented and the way each one contributed to extend the use of timber in construction.