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Showing posts from 2019

Greta Thunberg (15 years old) is My New Hero

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Greta Thunberg attended the Jan 2019 World Economic Forum at Davos and, in front of the world's most influential and powerful people, she said,  "Now is the time to speak clearly. Solving the climate crisis is the greatest and most complex challenge that Homo Sapiens has ever faced.   "The main solution, however, is so simple that even a small child can understand it.  We have to stop the emissions of greenhouse gases.  And either we do that or we don't.   "You say nothing in life is black or white but that is a lie; a very dangerous lie.  Either we prevent 1.5 degrees of warming or we don't.  Either we avoid setting off that irreversible chain reaction beyond human control or we don't.  Either we choose to go on as a civilisation or we don't.  That is as black and white as it gets.   "We must change almost everything in our current societies.  The bigger your carbon footprint is, the bigger your moral duty.  The bigger your platform,

Nominal Bracing Capacity of Plasterboard Walls is Conservative (maybe)

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In my last blog post I noted that full-scale testing by the Cyclone Testing Station (CTS) in Townsville had revealed that about 40% of the lateral load on a building is resisted by the plasterboard sheathing and cornices (Satheeskumar et al. , 2016).  As surprising as this might seem, it really shouldn't be at all surprising to structural engineers.  We know that architectural finishes add to the stiffness of a building.  This fact is clear from the dynamic behaviour of a finished building where the measured natural frequency of the building is almost always higher than the predicted natural frequency from software models ( i.e. , SpaceGASS, Etabs, Strand7, etc.), which typically neglect the non-structural elements. As part of my research, I am developing a suite of finite element (FE) models of mid-rise timber buildings (4 - 10 storeys) in order to predict the loading profile on the shear walls under earthquake and cyclonic loading conditions.  This will help me to plan the

Testing Shear Walls for Cyclone Resistance

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Structural engineers design buildings to safely resist gravity loads (vertical loads), such as the self-weight of the building and the weight of people and furniture, as well as loads from extremely rare events, such as earthquakes and cyclones (lateral loads - image below).  Gravity loads are transferred down through the building to the foundations via beams, columns and load-bearing walls.  Lateral loads are transferred through the structure via a series of interconnected horizontal diaphragms (roof and suspended floors) and vertical shear walls (see image above). Over the next few years I will be developing and testing shear wall systems for tall timber buildings, so I am interested in finding the best methods for laboratory testing of timber shear walls.  My early research on this topic has uncovered some practices which I find odd. In an ideal world we would construct shear wall prototypes to match practices on building sites and then test them under conditions that