Performance of timber-concrete composite members: a Study on connectors and failure modes

Abstract

In recent years, timber-concrete composite (TCC) structures have become increasingly popular across Europe for both new builds and renovations. These systems combine the benefits of concrete and timber: concrete provides excellent compressive strength, while timber offers tensile strength, lightweight properties, and aesthetic appeal. The concrete slab protects timber beams from moisture, enhancing durability, especially in bridges. Various connectors enable effective interaction between concrete and timber, ensuring structural performance. Factors such as material properties, connector type, and installation quality significantly impact performance. Among these, the type of mechanical connector and the connection angle are key influences. To evaluate bond efficiency, twelve specimens were subjected to identical shear-compression tests. Four configurations were tested: straight screws (SS), straight nails (SN), tilted screws (TS), and tilted nails (TN). Three specimens per configuration were constructed with Pino Radiata timber and M30 grade concrete. Results showed that nail bonds allowed greater deformation, but SS bonds performed best, resisting 1.158 ± 0.407 MPa—41.3% ± 34.8% stronger than SN, 110.7% ± 39.2% stronger than TS, and 118.9% ± 39.9% stronger than TN. Failure modes varied by bond type, with critical failure and timber-concrete slippage being the most common.