Shear capacity and slip modulus prediction of LVL and LVL-C nailed connections for LVL-I-beams

Abstract Banded laminated-veneer lumber (LVL-C) is an engineered wood product valued for its high bending, tensile and compressive strength along the grain, making it well-suited for long-span, high-load members such as composite LVL I-beams. In these beams, the web is usually a unidirectional LVL, whereas the flanges are fabricated from cross-banded LVL-C to improve dimensional stability and rolling-shear resistance. This study investigates the mechanical performance of nailed LVL–LVL-C connections that link the flange to the web. Sixty push-out shear tests were carried out on eight configurations, varying (i) nail type, (ii) nail spacing (45 mm vs. 75 mm), and (iii) flange thickness (19 mm vs. 37 mm). The experiments show that flange thickness is the governing parameter: specimens with the thinner flange reached, on average, 18–20 % higher load capacity, whereas the thicker-flange specimens exhibited greater initial and secant stiffness. Two characteristic failure mechanisms were observed: single-hinge web yielding, in which one plastic hinge develops in the weak (web) member, and double-hinge composite yielding, in which a second plastic hinge forms in the strong (flange) member. These mechanisms correspond to Johansen modes (e) and (f). A nonlinear beam-on-foundation (BOF) model was developed for the nails; the model reproduces both observed failure mechanisms and the full load–slip response. Calibrating the model yields embedment strengths roughly three times the values predicted by prEN 1995-1-1, reducing the mean error in capacity prediction from 46 % to less than 1 %. A complementary linear BOF formulation confirms that the slip modulus is highly sensitive to the effective embedment depth, explaining the marked stiffness difference between the two flange thicknesses. In summary, the combined experimental–numerical programme (i) provides revised embedment parameters for spruce LVL and LVL-C, (ii) shows that current Eurocode provisions are overly conservative for these materials, and (iii) offers a validated BOF framework for designing nailed connections in LVL I-beams.