Improving Design Efficiency, Reliability, and Safe Operation of Trussless Roofing Systems through Mechanics-Based Evaluation of Roof-to-Beam Base Connections

Abstract

Introduction. Trussless roofing systems employing curved cold-formed metal sheets are widely used in long-span industrial and public structures. Wind uplift and seismic excitation impose significant demands on the roof-to-beam base connection, where stress concentrations, local deformations, and bolt force imbalances govern structural performance and serviceability. Although local failure mechanisms at fasteners, clips, and seams have been extensively studied, no verified comparative framework exists for selecting base connection configurations specifically for trussless arched roof systems. The objective of this study is to evaluate the structural behavior of four field-constructible base connection systems — traditional mechanical anchor, cap plate, support bracket, and continuous steel frame — under identical loading conditions and to establish a mechanics-based basis for connection selection. Materials and Methods . AZ150 Galvalume steel panels (0.8 mm, 600 mm width, 20 m arch span) with explicit trapezoidal corrugation geometry were tested experimentally under simulated wind uplift (0.50–2.00 kN/m 2 ) and modelled numerically using ANSYS Mechanical with SHELL181 shell elements, surface-to-surface contact, Coulomb friction, and multipoint constraint bolt formulations. Wind pressure (1.0–2.0 kN/m 2 ) and seismic acceleration (0.10–0.25 g) were studied as factors in a two-factor response surface methodology design using Design-Expert v13. Model predictions were validated against laboratory deflection and base stress measurements, and cross-validated against independently published experimental data. Results. Mid-span deflection decreased from the traditional anchor to the continuous frame, with a maximum reduction of 20%. The peak von Mises stress at the base connection was reduced by 60.1%, and per-bolt demand in the continuous frame was halved relative to the traditional anchor. ANOVA confirmed that wind pressure was the sole statistically significant factor (p < 0.0001), while seismic acceleration had no detectable effect on vertical deflection or base stress intensity (p = 1.0000). FEA predictions agreed with experimental measurements within 6.8% for deflection and 7.2% for base stress. Discussion. The findings demonstrate that connection stiffness and contact continuity, rather than sheet material strength, govern the stress-strain state of trussless roof systems under service-level wind loading. The improvement across the four configurations is attributable to increased effective contact area and the transition from discrete bolt-dependent to distributed surface-based load transfer. Conclusion. A validated finite-element and response-surface-based framework has been developed for comparative assessment of trussless roof base connections. The continuous steel frame is recommended as the preferred connection for long-span trussless roofing, subject to further validation under field conditions and across extended seismicity ranges.