Keynote Address Session 1 Session 2 Session 3A Session 3B Session 4A Session 4B Session 5A Session 5B Session 6 Session 7 Poster Session 

Experimental Testing and Analytical Modelling of Damage-Avoidance Steel Connections using HF2V Damping Devices

G.W. Rodgers, J.B. Mander and J.G. Chase

Analytical modelling and model validation of high force-to-volume (HF2V) damping devices and a DAD non-dilating steel connection utilising these devices is presented. The 2D exterior connection design incorporates a top-hung angle for the beam-column connection and HF2V devices create a damage-free moment resisting connection. Experimental results show consistently repeatable hysteretic behaviour to 4% drift with neither stiffness nor strength degradation. The analytical model of the connection shows good agreement between experimental and model results. The rate-dependent model defines overall hysteresis using a predictor-corrector solution to the governing non-linear ODE. Based entirely on rational mechanics, the model does not require prior experimental data for empirical calibration, enabling simultaneous design of the desired connection mechanics and energy dissipation, and the device requirements.

Paper P38: [Read] [Presentation]

Seismic Behaviour of Timber Shear Walls with Load-limiting Slip-friction Connectors

Wei Loo, Pierre Quenneville and Nawawi Chouw

In the event of seismic overloading, timber shear walls have normally been designed to yield by allowing inelastic distortion of the sheathing to timber frame nailed connections, thereby reducing the likelihood of brittle failure of timber chords or plywood sheathing. A new concept in shear wall design involves the use of slip-friction connectors in lieu of standard hold-down connectors. Slip-friction connectors, originally developed for the steel framing industry, rely on the mobilization of friction across steel plates to resist loading up to a predetermined threshold. Upon this threshold being exceeded, relative sliding between the steel plates allows the shear wall to displace in an inelastic manner- but with minimal material yielding of nails or timber. Thus post-earthquake residual damage in the shear wall is expected to be significantly mitigated. This paper discusses the results of the numerical investigation of two types of timber shear wall with slip-friction connectors, standard and Midply. Results from a preliminary numerical analyses carried out by the authors are presented. The advantages of the shear wall incorporating slip-friction connectors are highlighted.

Paper P39: [Read] [Presentation]

Numerical Investigations on the Seismic Response of Multi-storey Hybrid Post-Tensioned Precast Concrete Frames with Non-tearing Floor Connections

Alejandro Amaris, Stefano Pampanin, Des Bull and Athol Carr

The effects of beam elongation in precast frame systems have been demonstrated to be a potential source of unexpected damage to precast floors. To control the damage to structural elements through the use of rocking systems, alternative solutions have been developed and are currently available to minimize floor damage. Recent research on an innovative “non-tearing floor” connection using “hybrid” (rocking-dissipating) connections has shown it to be efficient for mitigating the effects of beam elongation.

This contribution presents a series of numerical studies on multi-storey post-tensioned hybrid frames using non-tearing floor connections with different configurations, subjected to pushover and time history analyses to investigate and evaluate the performance of this type of system to earthquake loading. The seismic response of the frames is compared with more traditional systems where the problems of beam elongation and floor damage can be appreciable. The response of the frames confirmed the unique flexibility of the proposed solution and highlighted the superior performance under seismic loading with only minor damage to the frame, wall and floor systems.

Paper P40: [Read] [Presentation]

Permanent Deflection Identification of Non-linear Structures Undergoing Seismic Excitation Using Adaptive LMS Filters

Mostafa Nayyerloo, Geoffrey Chase, X.Q. Chen, Gregory MacRae and Masoud Moghaddasi

Structural health monitoring (SHM) algorithms based on Adaptive Least Mean Square (LMS) filtering theory can directly identify time-varying changes in structural stiffness in real time, are robust to noise, and computationally efficient. Common modal or wavelet methods are less robust to noise and small levels of damage. However, the best metrics of seismic structural damage are related to permanent and plastic deformations, which no reported methods identify. This research uses LMS-based SHM methods with a baseline non-linear Bouc-Wen structural model to directly identify permanent deflection and changes in stiffness (modelling or construction error), in real-time. As a preliminary stage, the algorithm is validated, in silico, on an equivalent single degree of freedom (ESDOF) of a non-linear 5-storey shear-type concrete structure using MATLAB® without presence of noise on simulated structural responses. The Cape Mendocino ground motion is scaled to a level that causes permanent deflection to show the algorithm’s capability. For the simulated structure, the algorithm identifies stiffness changes to within 10% of true value in 2.0 seconds, and permanent deflection is identified to within 0.5% of the actual as-modelled value using noise-free simulation-derived structural responses.

Paper P41: [Read] [Presentation]

Keynote Address Session 1 Session 2 Session 3A Session 3B Session 4A Session 4B Session 5A Session 5B Session 6 Session 7 Poster Session