Structural systems have been evolving in terms of material properties and construction techniques, and their levels of protection against hazardous events have been the focus of different studies. For instance, the performance of the lateral force resisting systems has been investigated extensively to ensure that such systems would provide an adequate level of strength ductility capacity when subjected to seismic loading. However, with the increased occurrence of accidental and deliberate explosion incidents globally by more than three fold from 2004 to 2012, more studies have been focusing on the performance of such systems to blast loads and the different methods to quantify the inflicted damage.
Although both blast and seismic design requires structures to sustain a level of ductility to withstand the displacement demands, the distributions of such demands from seismic ground excitation and blast loading throughout the structural system are completely different. Therefore, a ductile seismic force resisting system may not necessarily be sufficient to resist a blast wave. To address this concern, North American standards ASCE 59-11, CSA S850-12 provide response limits that define the different damage states that components may exhibit prior to collapse.
Over the past ten years, a new configuration of reinforced masonry (RM) shear walls utilizing boundary elements (BEs) at the vertical edges of the wall has been investigated as an innovative configuration that enhances the wall’s in-plane performance. As such, they are included in the North American Masonry design standards, CSA S304-14 and TMS 402-16 as an alternative means to enhance the ductility of seismic force resisting systems. However, investigations regarding the out-of-plane performance of such walls are generally scarce in literature which hindered the blast design standards from providing unique response limits that can quantify the different damage states for RM walls with BEs.
This dissertation has highlighted that some relevant knowledge gaps may lead to unconservative designs. Such gaps include (a) the RM wall with BEs out-of-plane behavior and damage sequence; and more specifically, (b) the BEs influence on the wall load-displacement response; as well as, (c) the applicability of using of the current response limits originally assigned for conventional RM walls to assess RM walls with BEs. Addressing these knowledge gaps is the main motivation behind this dissertation.
In this respect, this dissertation reports an experimental program, that focuses on bridging the knowledge gap pertaining to the out-of-plane performance of seismically-detailed RM shear walls with BEs, which were not designed to withstand blast loads.
Meanwhile, from the analytical perspective, plastic analyses were carried out taking into account the different mechanisms that the wall may undergo until peak resistance is achieved. This approach was adopted in order to quantify the resistance function of such walls and determine the contribution of the BEs and web to the overall wall resistance. In addition, the experimental results of the tested walls were used to validate a numerical finite element model developed to compare the resistance function of RM walls with and without BEs. Afterwards, the model was further refined to capture the walls’ performance under blast loads. The pressure impulse diagrams were generated to assess the capability of the current response limits in quantifying the different damage states for walls with different design parameters.
Furthermore, new response limits were proposed to account for the out-of-plane ductility capacities of different wall components. Finally, a comparison between conventional rectangular walls and their counterparts with BEs using the proposed limits was conducted in the form of pressure-impulse diagram to highlight the major differences between both wall configurations. / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/24419 |
| Date | January 2019 |
| Creators | El-Hashimy, Tarek |
| Contributors | El-Dakhakhni, Wael, Tait, Michael, Civil Engineering |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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