Finite Element Modeling and Analysis of the Asymmetric Friction Connection (AFC) With and Without Belleville Springs (BeSs)

Abstract

This research investigates the seismic performance of the Asymmetric Friction Connection (AFC) and its enhanced form, the Optimised Asymmetric Friction Connection (OAFC), which serve as the primary energy-dissipating components of the Sliding Hinge Joint (SHJ) system for low-damage moment-resisting steel frames. The study focuses on developing, validating, and applying advanced finite element models and analysis (FEM/FEA) to interpret and expand upon the experimental findings previously conducted by Dr Shahab Ramhormozian, thereby providing a deeper understanding of the connection’s sliding behaviour and performance optimisation.

The experimental programme by Dr Ramhormozian provided full-scale AFC and OAFC test data under quasi-static and dynamic cyclic loading, including bolt-tension evolution, clamping-force variation, and sliding hysteresis. In the present research, these results were analysed in detail to identify the mechanisms governing post-sliding bolt-tension loss and to establish the optimal installed bolt pretension level. It was observed that bolts tensioned to approximately 50–60 % of their proof load offered the most stable and repeatable sliding performance, whereas higher pretension levels induced excessive plastic deformations and accelerated tension degradation.

Using ABAQUS/Standard, this study developed nonlinear FEMs for both AFC and OAFC assemblies, supported by mesh-convergence, element-type, and contact-interaction investigations to ensure accuracy and computational efficiency. The validated models adequately reproduced the experimentally observed hysteresis loops, clamping-force evolution, and bolt-tension variation. Incorporating partially deflected Belleville Springs (BeSs) in the OAFC models demonstrated markedly improved preload retention and smoother force–displacement responses. Furthermore, wear-induced degradation was simulated through temperature-controlled contraction, reproducing the experimentally observed reductions in clamping force and sliding resistance over cyclic loading.

Comparative analyses showed that while the conventional AFC experienced up to 60 % clamping-force loss, the OAFC limited this reduction to 15–20 %, resulting in superior energy dissipation, improved self-centring capability, and enhanced durability. The developed FEM framework thus provides a validated, detailed computational tool for parametric studies and design optimisation of OAFCs and related low-damage seismic systems.

Overall, this thesis refines and extends the interpretation of prior experimental results through advanced numerical analysis, contributing to the design and implementation of resilient, friction-based steel connections for low-damage seismic structures.