Browsing by Author "Zhang, Hanhui"

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A fracture energy based damage-plasticity interfacial constitutive law for discrete finite element modelling of masonry structures
(2019-08-01)
Yuen, Terry Y. P.
;
Deb, Trissa
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Zhang, Hanhui
;
Liu, Yang
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土木工程學系
The robust structural design relies on the accuracy of the response analysis to different loadings. Strut-and-tie models and continuum models are often used for the design of masonry structures but they are generally not able to simulate detailed damage and progressive collapse. To this regard, this paper presents a new and robust interfacial constitutive law, which couples the damage and plastic deformation with fracture energy-based softening rules, for the discrete finite element modelling (DFEM) of masonry structures. The model has 14 required parameters and 2 optional parameters of which calibration methods using the standard test data and physical rules are provided in details. It was demonstrated that the comprehensive mechanical behaviour including the pressure-dependent fracture, wearing-off of the friction, dilatation, stiffness degradation, shear retention, and component disintegration can be well captured. The model validation studies were performed with various material and structural tests including shear-compression and uniaxial tension tests on the joints, and horizontal loading and shake-table tests on large-scale masonry structures. Good agreements between the simulated and experimental results could be observed. Comparing to conventional modelling approaches, the DFEM with the interfacial constitutive law can also simply the meshing work and better control the mesh quality. (C) 2019 Elsevier Ltd. All rights reserved.
Low-seismic damage strategies for infilled RC frames: shake-table tests
(2017-11-01)
Zhang, Hanhui
;
Kuang, J. S.
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Yuen, Terry Y. P.
;
土木工程學系
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Department of Civil Engineering
Unreinforced masonry (URM) infill panels are widely used as partitions in RC frames and typically considered as non-structural elements in the design process. However, observations from recent major earthquakes have shown that under seismic excitation, the structural interaction between columns and infill walls can significantly alter the structural behaviour, thus causing catastrophic consequences. The purpose of this research was to propose and test an innovative low seismic damage detailing method, which isolates the infill panel from bounding columns with finite width vertical gaps during the infill panel construction phase and deploys steel wire connections in mortar layers anchored to columns. Taking into account the similitude requirements, a total of six one-third scale, single-storey single-bay RC frames with different infill configurations and flexible connection details were carefully designed and tested on a shake-table. Three real earthquake records were selected and scaled to ascending intensity levels and used as input signals. A series of thorough investigations including dynamic characteristics, hysteretic behaviour, failure mechanisms, out-of-plane vulnerabilities and the effect of different gap filling materials and load transfer mechanisms were rigorously studied. The experimental results indicate that the undesirable interaction between infill panels and bounding frame is significantly reduced using the proposed low seismic damage detailing concept. Direct shear failure of columns at an early stage is prevented, and structural redundancy at high levels of excitation can be provided. In general, the structural stability and integrity, and displacement ductility of infilled RC frames can remarkably be improved. Copyright (C) 2017 John Wiley & Sons, Ltd.