Experimental evidence for effective flexural-only stiffnesses to account for nonlinear flexural-slip behaviour of timber-concrete composite sections

- Concept of equivalent section flexural stiffness, variable along TCC span.
- Unique instrumentation layout to generate data to validate this concept.
- Demonstration that gamma method can be significantly improved upon using this approach.
- Illustration that nonlinear behaviour can be dealt with without unduly complex computations.

The nonlinear behaviours of timber-concrete composite (TCC) members can be predicted via linear beam element analyses. The key is to quantify effective flexural-only stiffnesses (B) that capture the material nonlinearities from flexure-slip action of the TCC section, and to conduct the analyses using B profiles which satisfy equilibrium, compatibility and nonlinear constitutive links to the connections. This paper demonstrates the manner in which ad-hoc instrumentation of a TCC specimen can underpin validation of that concept. The test-based nonlinear B profiles along the span are found to out-perform the Gamma method (which assumes uniform B) in load response prediction. Finally, future research to broaden this approach is outlined.