Energy, Geoscience, Infrastructure and Society
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Item Novel structural details to mitigate progressive collapse in steel nominally-pinned joints(Heriot-Watt University, 2021-08) Ghorbanzadeh, Benyamin; Muhsin, Sean; Vasdravellis, Doctor George; Cotsovos, Doctor DemitriosSteel structures are frequently used worldwide. The beam-column connections play a vital role in those structures. In a case of column removal due to blast, fire or vehicle impact, the disproportionate collapse can occur if the robustness of the joint is not enough and the failure propagates to other members. Current design practices require that the beam-column joints shall withstand a minimum tie force to prevent progressive collapse. However, several pieces of research have shown that nominally pinned joints which are commonly used in steel frames cannot provide the required tie force while undergoing significant rotations imposed by a column removal event. The present thesis proposes a set of novel structural detail to be added to the steel nominally pinned joints to arrest progressive collapse by enhancing both their tensile resistance and rotation capacity. The proposed structural details exploit the exceptional strength and ductility of Duplex stainless steel pins (SSPs) under bending which allows them to withstand excessive deformation prior to their fracture. First, the monotonic fracture capacity of SSPs was experimentally evaluated followed by the calibration of numerical models with the capability of predicting fracture of SSPs. Employing the calibrated numerical models, a set of parametric study was carried out on various geometry properties of SSPs to develop a design procedure to reliably achieve the required levels of tie force and rotation in a joint. An experimental programme including static and dynamic tests on the proposed joint was presented, discussed, and simulated in Abaqus. In addition, more analyses were conducted to determine the Dynamic Increase Factor (DIF). Finally, the proposed joint was modelled as a 3D connection including the primary and secondary directions. It was observed that the proposed joint significantly increases the joint rotation while providing appreciable tie force compared to standard fin plate connection.Item Simulation and mitigation of water conservation consequences in a domestic UK wastewater collection system(Heriot-Watt University, 2021-08) Muhsin, Sean; Campbell, Doctor DavidDomestic water conservation strategies have already resulted in water use reduction. Water use is considered energy-intensive, which means that a reduction in water use will also reduce carbon emissions and therefore contribute to climate change mitigation strategies. However, a reduction in water use will automatically reduce wastewater flow and negatively impact solid transportation and therefore wastewater system performance thereby making the system more susceptible to blockages. Furthermore, it may also deliver wastewater to the treatment plant that is outside of required plant operational parameters. These two concerns could result in greater carbon emissions than carbon savings. This highlights the necessity to determine the optimal water reduction level of water conservation strategies, as opposed to simply ‘the maximum reduction possible’. The UK Building Codes control the dimensional layout of building wastewater systems and would need to be updated to make use of optimal water reduction guidance advice. This dissertation fills this gap by postulating a general optimum water conservation level of between 20%-40% before adverse performance manifests, by using verified computer simulations primed with verified site data, derived in collaboration with a national-level Steering Panel comprised of UK Water Industry Research members. Guidance and recommendations include allowing 75mm discharge pipes and tipping tanks to facilitate aggressive water conservation tactics while maintaining adequate wastewater system performance and still conserving water.