- Title
- Modelling of semi interlocking masonry based on observed behaviour
- Creator
- Hossain, Md Akhtar
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2019
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- The Semi Interlocking Masonry (SIM) system is presently being developed in the Centre for Infrastructure Performance and Reliability at The University of Newcastle, Australia. In seismic areas, SIM can be used in the form of framed mortarless engineered panels, which have significant energy dissipation capacity due to the sliding friction between units induced during an earthquake. The mortarless joints of SIM could be dry or could have some non-adhesive joint filler for improving SIM’s water resistance and thermal insulation. The main topic of this thesis concerns the study of the in-plane behaviour of SIM panels. The study is composed of three parts: a vast experimental part, carried out in the Civil Engineering Laboratory at The University of Newcastle; a numerical part, with the purpose of analyzing the frictional behaviour of SIM joints under constant pre-compression loading; and a theoretical part, to assess the feasibility of SIM panels in Australia. The experimental part of this study was organized in two main parts: experimental tests on bed joints in SIM, and experimental tests on full-scale SIM panels subjected to large in-plane lateral displacement. In this thesis, an experimental and numerical study was conducted to investigate the frictional capacities of three different mortarless SIM bed joint surfaces (dry surface, surface with linseed oil based putty, and surface with rubber foam tape). The investigation aimed to replicate realistic boundary conditions and loading regimes using a modified couplet shear test set-up. At first a triplet shear test was adopted to determine the frictional behaviour of SIM joints. However, it was found that the pre-compression level was fluctuating during cyclic loading. Following this, the couplet test, which is similar to the van der Pluijm test, was adopted, with the pre-compressions applied to the specimen by the static gravity load. The tests were designed to simulate the relative sliding of SIM units during earthquakes over the service life of a panel were used for comparison to dynamic frictional behaviour: 160 sliding cycles of ± 1mm relative displacement applied dynamically (100 mm/minute). In addition, 1 cycle of ±10 mm displacement was also applied statically (10 mm/minute). The load-displacement history was recorded. Three levels of pre-compression were applied to observe the effect on shear forces for different SIM bed joint surfaces. The shear force was highly influenced by the pre-compression, giving higher values for higher levels of pre-compression. The thesis reports the results of this testing program in terms of the friction coefficient (based on the Mohr-Coulomb failure criterion) and the energy dissipation evolution for each type of joint. A micro finite element model was developed and validated against the experimental results. The predicted load-displacement hysteresis for different surfaces from the model were in good agreement with the experimental results for the static testing. However, the model cannot predict the load-displacement hysteresis for the dynamic testing. As the SIM system attempts to improve the earthquake performance of the framed structure by increasing the displacement ductility and the energy dissipation capacity of infill panels, it is essential to test the SIM panels under large cyclic in-plane displacement. The study focused on an experimental investigation of the displacement capacities of three different types of panels (panel with an open gap between the frame and top of the panel, panel with foam in the gap, panel with grout in the gap), made of two types of SIM units, under large cyclic in-plane displacement. This study provides a step forward towards a better understanding of the earthquake performance of SIM panels. A special steel testing frame with pin connections was built to test the SIM panels. The arrangement with the pin connections allows the application of in-plane displacement of up to 120 mm (storey drift 6%). Six full-scale SIM panels were constructed with joint filler and tested under the in-plane cyclic displacement. This study addresses the response of SIM panels to large displacements in terms of force-displacement behaviour, strength degradation, energy dissipation and displacement ductility. As SIM is a new masonry system, it is important to study the load-displacement behaviour. In this study, a new approach was developed to idealize the load-displacement response of SIM infill panels. The force-displacement response of SIM panels can be approximated by two equivalent bilinear relationships. The horizontal and vertical movement of the SIM units was recorded using Digital Image Correlation (DIC) every 10 seconds over approximately 8 hours of testing. It was found that the DIC displacement outputs has good agreement with displacements measured using traditional instrumentation, even at large displacements (up to 100 mm). The structural performance of the SIM panels was also analyzed and potential crack pattern and joint opening widths are quantified under large displacement by plotting the outputs from the DIC results. An analytical model was developed to assess the feasibility of using SIM panels in seismic regions of Australia. Two types of analytical models were developed for the SIM panel with open gap and the SIM panel with closed gap at top of the panel. The results from the analytical study were compared with the experimental results. It was found that the analytical model is capable of predicting the response of the SIM panels with open gap and SIM panels with closed gap. The results also show that the SIM infill panels are a viable alternative to traditional unreinforced masonry panels in seismic areas.
- Subject
- semi interlocking masonry; sliding joints; in-plane cyclic testing; energy dissipation; digital image correlation; large horizontal displacement; SIM; large storey drift; friction testing; DIC
- Identifier
- http://hdl.handle.net/1959.13/1410373
- Identifier
- uon:36172
- Rights
- Copyright 2019 Md Akhtar Hossain
- Language
- eng
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 36 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 311 KB | Adobe Acrobat PDF | View Details Download |