MECHANICAL CHARACTERISTICS AND FAILURE MECHANISMS OF TIMBER-CONCRETE COMPOSITE CONNECTIONS WITH INCLINED STEEL RODS
DOI:
https://doi.org/10.36773/1818-1112-2025-138-3-84-93Keywords:
timber-concrete composite structure, inclined bolted connection, ANSYS finite element analysis, slip modulus, bolt clearance, European yield modelAbstract
The application of Timber-Concrete Composite (TCC) structures in long-span floor systems is becoming increasingly widespread, and their collaborative efficiency highly depends on the shear stiffness and load-bearing capacity of the interface shear connectors. Although inclined self-tapping screws significantly improve connection stiffness by utilizing axial tensile force, the mechanism by which the mechanical behavior of large-diameter inclined connections with bolts steel rods, which have higher load-bearing capacity and require greater construction tolerance, is influenced by the constraints of hole clearance and concrete slab thickness remains unclear.
This paper proposes a comprehensive research scheme combining theoretical derivation, full-scale experiments, and high-fidelity numerical simulation for a TCC system composed of a 70 mm thin concrete slab and a 160 mm timber beam. The study aims to quantify the coupling effect of the diameter of the bolts steel rods (d = 6, 8, 12 mm) and inclination angle (α = 30°, 45°, 60°), focusing on solving two key problems: initial slippage caused by the clearance of the bolts steel rods and brittle punching out of thin slabs. In the numerical simulation stage, this study will use ANSYS finite element analysis software to establish a three-dimensional nonlinear solid model. ANSYS's powerful contact algorithms will be used to accurately simulate the closing process of the gap between the shank of the bolts steel rods and the hole wall. Combined with the concrete damage plasticity model (CDP) illustrated in Figure 2a, which can simultaneously, the evolution of failure modes under different working conditions will be predicted.
Expected results show:
1) ANSYS-based contact analysis will reveal that a 30° tilt angle can produce a significant geometric self-locking effect, effectively suppressing the initial stiffness loss caused by pre-drilled hole gaps;
2) in a 70 mm thin plate, 12 mm diameter bolts steel rods easily induce concrete cone failure, and numerical simulation will provide the critical parameter boundary to avoid this brittle failure. The results of this paper will correct the existing European Yield Model (EYM), providing a design basis based on high-precision simulation for the reinforcement and renovation of thin-plate concrete structures in existing timber floor slabs.
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