Blast loads on buildings can originate from accidental explosions or from targeted attacks. Design against blast loads has become an increasingly important topic due to the current political climate. Unfortunately, many older buildings are constructed with unreinforced masonry (URM) walls which are particularly susceptible to out of plane failures caused by blast loads. One solution to increase the safety of these buildings is to retrofit them with advanced materials that can increase their out-of-plane stiffness and resistance. This thesis investigates the potential of using a high-performance shotcrete as a retrofit system for URM walls against blast effects. The shotcrete used in this study is made from Engineered Cementitious Composite (ECC), a special type of fiber-reinforced cementitious material, with high ductility and high energy-absorption capacity. The ECC shotcrete replaces aggregates with synthetic microfibers to increase tensile strength and ductility. A welded wire mesh was embedded in the shotcrete to provide ductile behavior. The testing program includes a total of six large-scale unreinforced masonry wall specimens. Two walls were constructed using concrete masonry unit (CMU) blocks to be retrofitted. The first specimen was built as an infill wall, experiencing no axial load, while the second specimen was built as a load bearing wall, with 10% axial load. Four more walls were built out of stone blocks. Two of the stone walls were controls: one infill and one load bearing (4% axial load). The other two stone walls were retrofit with the shotcrete system: one infill and one load bearing (4% axial load). The blast loads were simulated using the University of Ottawa’s Shock Tube. The walls were restrained at the top and bottom with a shear restraint to induce one way bending. Pressure, displacement and strain data were acquired with the use of pressure gauges, LVDT’s, strain gauges and cameras. The specimens were subjected to gradually increasing blast pressures until failure. The performance of the specimens was observed by analyzing the displacement, crack widths, fragmentation and failure mode. The results indicate the benefits of using ECC shotcrete as a retrofit system. The displacements of the retrofit walls were very small compared to the control walls, and fragments were limited. The specimens with axial load were found to have increased resistance. While the failure mode was brittle for the retrofit walls, this can be avoided with the use of a mesh with a larger area of steel. A SDOF analysis was performed to predict the blast response of the test walls. The analysis was done by generating resistance functions for the walls through analytical models. The analysis was found to agree reasonably well with the experimental data.

The dissertation provides a solution to the existing Boukunde buildings spatial shortfall. A proposal for additional space is used as catalyst for improving daylight conditions within the 'dark' southern extents of the building. The expansion becomes a gateway for future works by opening up a once impervious shell and services core to regenerate space plan potential and circulatory flow. The buildings origins and evolution are investigated to ascertain the lessons learnt, and to create a visual reference to the past via aspects of the new construction. The reference is extended via recycling of existing materials and components into the proposal in an altered, but recognisable format. / Dissertation (MArch(Prof))--University of Pretoria, 2009. / Architecture / unrestricted

Glass facade/curtain wall assemblies are commonly used in modern building construction as part of building envelop. This system has a number of advantages, including pleasant architectural appearance, building energy optimization, acceptable fire resistance and low maintenance. However, they pose tremendous risk towards maliciously intended acts of terror in the form of bomb blasts. The literature review conducted revealed lack of previous research on mullion strengthening/hardening. The present study has the objective of developing hardening techniques for curtain wall mullions to withstand high-intensity impulsive blast loads. Combined experimental and analytical research was conducted for the development of mullion retrofit techniques using the Shock Tube Facility of the University of Ottawa. The test program involved retrofitting existing, commercially used aluminum mullions with steel plates and subjecting them to different levels of blast loads. The mullions were retrofitted with three techniques with the help of steel L shaped angles, steel plates and with a combination of steel HSS sections and plates. The results indicated an increase of load carrying capacity of the mullions up to a factor of 2.2 with up to 30% reduction in mid-height displacements. It was shown that the steel hardening components developed full composite action with the existing aluminum section, indicating the effectiveness of the hardening technology. The analytical research followed the experimental research with the main objective of validating experimental results, as well as validating the assumption of full composite action between the core aluminum mullion and the hardening plates. The first step was to develop resistance functions followed by the validation of main analytical tool RC-Blast and the UFC charted solution. Following excellent agreement between these two analytical tools, RC-Blast was further validated against the experimental results. In addition, Pressure-impulse (P-I) diagrams were developed as design aids for different pressure-impulse combinations. The retrofit techniques developed were applied to a selected prototype building to assess their feasibility for use in practice. Two different blast threats were considered for this application. Conclusions were drawn regarding the effectiveness of the curtain wall hardening techniques for use in practice.

Lateral forces generated by wind, earthquakes, and other horizontal loads are trans-mitted from the floor diaphragms to the columns and walls that comprise the vertical lateral force resisting system in a building. Strengthening of the diaphragms in older reinforced concrete buildings may be necessary for several reasons, including to enhance seismic performance, address inadequate strength or stiffness, provide missing or incomplete load paths, improve inadequate shear transfer/connection capacity, and to accommodate changes in the use and occupancy of the structure. Engineers are currently using externally bonded fiber reinforced polymer (FRP) composites to retrofit deficient diaphragms. However, this application is beyond the scope of current FRP-related design documents, including ACI PRC-440.2R-17 "Guide for the Design and Construction of Externally bonded FRP Systems for Strengthening Concrete Structures". The lack of consensus around design recommendations for FRP strengthening of diaphragms is problematic and creates uncertainty about which approaches are proven and what are best practice. This thesis summarizes the results from an experimental research program designed to investigate the shear behavior of reinforced concrete diaphragms strengthened using external-ly bonded FRP. Six one-half scale reinforced concrete cantilever diaphragms were tested in shear to evaluate the influence of FRP material, density, spacing, orientation, and intermediate anchorage configuration on the performance of diaphragm strengthening. The specimens were designed to represent the diaphragm shear zone adjacent to a shear wall in a concrete building. The tests were performed using a reverse cyclic displacement protocol representative of earthquake actions. The tests included a baseline unretrofitted concrete specimen, followed by five retrofitted specimens with different configurations of externally bonded FRP. Each retrofitted specimen was designed to maintain a similar FRP axial stiffness while varying the FRP retrofit parameters. The results demonstrated that externally bonded FRP retrofitting improved both the shear strength and stiffness of the strengthened test specimens. All the retrofitted specimens experienced an FRP debonding failure initiated by intermediate shear cracks with the field of the diaphragm, occurring after yielding of the internal steel rebar. The results highlighted that the overall behavior of the specimens was influenced by the way the retrofit schemes were proportioned and detailed. For example, the application of FRP parallel to the direction of applied shear was found to be most effective at increasing the diaphragm strength. Conversely, the application of FRP perpendicular to the applied shear was found to increase the diaphragm ductility. In addition, the shear strength contribution of externally bonded FRP was significantly influenced by the retrofit surface coverage. Compared with narrow strips of high-density fabric, retrofits detailed with less dense fabric spread uniformly over the surface exhibited superior performance due to better control of the shear cracks. Furthermore, no meaningful difference in performance was observed between diaphragms strengthened with glass and carbon FRP composites, provided the retrofits were proportioned to achieve com-parable levels of stiffness. This finding suggests that either type of fabric may be suitable for diaphragm strengthening. Finally, the use of overstrength intermediate FRP anchors did not noticeably affect the FRP shear strength contribution. However, the presence of intermediate anchors led to localized failures that concentrated inelastic diaphragm response between anchor locations, resulting in a significant reduction in diaphragm deformation capacity. The test results were used to develop design recommendations for shear strengthening existing concrete diaphragms using externally bonded FRP. The recommendations included guidance on how to establish the effective FRP design strain and the nominal shear strength contribution of the FRP, both of which tended to be conservative and underestimated the actual behavior observed during the experiments. The recommendations also address the use of intermediate and end FRP anchors, limitations on the clear spacing between sheets, and other factors pertinent to retrofit design. / Master of Science / The floor diaphragm in a reinforced concrete building transmits lateral forces generated by wind, earthquakes, and other horizontal loads to the building's vertical lateral force resisting system. Diaphragms in older reinforced concrete buildings are often retrofitted to meet seismic demands. Retrofitting deficient diaphragms increases infrastructure sustainability by promoting reuse and reconfiguration of existing buildings while mitigating structural deficiencies. Using externally bonded fiber reinforced polymer (FRP) composites is a com-mon strengthening technique often used without supporting guidance or test data. An industry need for diaphragm retrofit provisions, coupled with a substantial lack of data clearly indicates a need for experimental testing of diaphragm elements strengthened with externally bonded FRP. This thesis summarizes the results from an experimental research program designed to investigate the shear behavior of reinforced concrete diaphragms strengthened using externally bonded FRP. Six reinforced concrete diaphragm specimens were tested to study how variations in FRP material, density, spacing, orientation, and anchorage configuration impacted the performance of the retrofit. One specimen served as a control while the five other specimens were retrofitted with various configurations of FRP. The control specimen experienced a diagonal tension shear failure while each FRP strengthened specimen exhibited an FRP debonding failure, which was initiated by intermediate shear cracks occurring within the field of the diaphragm. The experimental results were analyzed to understand how the FRP retro-fits affected the strength, stiffness, ductility, and energy dissipation of each specimen. It was concluded that externally bonded FRP improves the seismic performance of a building by increasing the in-plane shear strength of the diaphragm. Existing design provisions were evaluated and compared to the experimental findings. Design recommendations were formed based on the observed affect of the test variables.

No description available.

Sustainable Built Environments Senior Capstone Project / Climate change and resource availability are arguably the two biggest challenges humanity faces going forward. An unprecedented body of scientific work has been compiled over the past thirty years that indicates humans have and continue to be the largest driver of these environmental concerns, and therefore must also be responsible for any solutions. Buildings and their construction account for nearly 40% of the total energy consumption and greenhouse gas emissions in the United States. Water consumption by both buildings and thermoelectric power generation is also an issue, especially in the Southwest and Western United States. Green building has been gaining steam in the U.S. for the past two decades, but the primary focus has been in the commercial and industrial sectors. The residential markets have not seen the efficiency gains, primarily due to the perception that the cost isn’t worth the benefit. This project examines the need, feasibility, and potential benefits of sustainably retrofitting existing homes as an alternative to new construction. It provides a broad definition of sustainability and then focuses into a more narrow description of its application within the built environment. Using precedents, 3D modeling, and energy simulation software it compares the energy and water savings of a retrofit versus a base case as well as the performance of the average Southern Arizona home. Finally, this capstone project provides a professional cost estimate for the implementation of the proposed changes and a side-by-side look at the available “green” housing market, the utility cost savings for the homeowner, and the environmental benefits of individual as well as large-scale adoption of sustainable retrofitting practices.

Bridges are the most critical components of the transportation network. The functionality of bridges is important for hurricane aftermath recovery and emergency activities. However, past hurricane events revealed the potential susceptibility of these bridges under storm induced wave and surge loads. Coastal bridges traditionally were not designed to sustain hurricane induced wave and surge loads; and furthermore, no reliability assessment tool exists for bridges exposed to this hazard. However, such a tool is imperative for decision makers to evaluate the risk posed to the existing bridge inventory, and to decide on the retrofit measures and mitigation strategies. This dissertation offers a first attempt to quantify the structural vulnerability of bridges under coastal storms, offering a probabilistic framework, input tools, and application illustrations. To accomplish this goal, first an unbiased wave load model is developed based on the existing wave load models in the literature. The biased is removed from the load models through statistical analysis of the experimental test data. The developed wave load model is used to evaluate the response of coastal bridges employing single-physics domain Dynamic numerical models. Additionally, a high fidelity fluid-structure interaction model is developed to take into account the significant intricacies, such as turbulence, wave diffraction, and air entrapment, as well as material and geometric nonlinearities in structure. This numerical model provides insight on the influential parameters that affect the response of coastal bridges. Moreover, a Monte Carlo based Static Model methodology is developed to enable fast evaluation of the bridge deck unseating mode of failure. This methodology can be used for fast screening of vulnerable structures under hurricane induced wave and surge loads in a large bridge inventory. New statistical learning tools are used to develop fragility surfaces for coastal bridges vulnerable to storms. The performance of each of these tools is evaluated and compared. The statistical learning approaches are used to enable reliability assessment using the more rigorous finite element models such as the Dynamic and FSI Models which is important for improved confidence and retrofit assessment. Additionally, a new systematic method to evaluate the limit state capacity functions based on the post-event global performance of the bridge structure is developed. The application of the developed reliability models is illustrated by utilizing them for Houston/Galveston Bay area bridge inventory. The case study of Houston/Galveston Bay area reveals that more than 30% of bridges have a high probability of failure during an extreme hurricane scenario event. Two vulnerable bridge structures from the case study are selected to investigate the effect of different potential retrofit measures. Recommendations are made for the most appropriate retrofit measures that can prevent the deck unseating without significantly increasing the structural demands on other components.

Highway bridges function as the arteries of our society. Hence, it is essential that they remain operational following an earthquake. Unfortunately, a significant number of bridges worldwide, including in Canada, were constructed prior to the development of modern seismic design provisions. In many cases, such bridges are expected to perform poorly during earthquakes. According to a report published in 2000 by Ministry of Transportation of Ontario (MTO), in eastern Ontario alone, there are over 70 bridges that are structurally deficient. Current methods to retrofit these bridges to bring them into compliance with the existing codes would entail substantial structural modifications. Examples of such modifications include the replacement of existing rocker bearings with elastomeric bearings, structural strengthening of piers, and enlarging the bearing surfaces. These methods involve substantial cost, effort, and materials. An alternative means to retrofit structurally deficient bridges is investigated in this thesis. This method involves using a combination of elastomeric bearings and fluid dampers to retrofit highway bridges. In principle, these devices work in the same way as shock absorbers in automobiles. They absorb shock and dissipate the vibration energy to the environment as heat. In the case of bridges, earthquakes impart the shock to the structure. Before these devices can be implemented in practice, there are many issues that need to be understood with respect to their performance and modelling. Moreover, a comparative assessment between popular retrofit options employing isolation systems needs to be undertaken to verify and provide a benchmark to assess their performance. The Mississippi River Bridge near Ottawa is chosen as a test structure to conduct this study. This bridge already contains an advanced isolation system, and has an extensive documentation available for modelling and verification. Various retrofit options will be studied and compared with the existing isolation design for this bridge. In all cases, the effect of soil-structure interaction is included. A comprehensive set of performance indices are used to evaluate the performance of various retrofit options. All the models are constructed in the open source software, OpenSees. The research demonstrates that the proposed approach is a viable retrofit method for highway bridges. Moreover, compared to advanced isolation systems, retrofit using elastomeric bearings with viscous dampers was successful on transferring lower loads to the substructure, and resulted in lower superstructure displacements. Though this study involved one bridge, it has provided a computational test bed to perform further studies and has provided valuable insight into the modeling and performance of retrofit solutions.

First generation bioethanol generated from feedstocks is a sustainable alternative to fossil fuels, and the demand for fuel ethanol has promoted studies on the use of the grain as feedstock. This thesis describes various process designs and the economic feasibility for producing the main product ethanol and other by-products such as Biogas and DDGS (Distillers Dried Grains with Solubles) from the grain. The techno-economic analysis was performed by the data provided by Agroetanol industry, located in Norrköping, Sweden. The key target of this simulation work was to evaluate the influence of several process designs and the main production factors on the ethanol production process, in terms of energy efficiency, ethanol production cost and plant profitability. The main aim of this work was to simulate the current industrial process and to develop novel alternative retrofits by integrating new technologies and for investigating the effects on the plant profitability. In the base case, the cost sensitivity analysis was carried out on the grain buying price, ethanol and DDGS selling price. Along with the cost sensitivity analysis, the capacity sensitivity analysis was performed on the base case model to check the influence of different capacities on the plant profitability. While coming to the study of developing alternative retrofits, the three retrofits were developed on the base case process and they are as following: Retrofit 1) modifying the distillation and dehydration section of the base case retrofit (current process in Agroetanol), Retrofit 2) checking the impact of ethanol concentration on technical and economic aspects of the plant and Retrofit 3) installing the biogas digester.The modelling effort resulted in developing the base case model with an ethanol production rate of 41,985 ton/ year. The capital cost of the base case process was calculated to be at 68.85 million USD and the aspen economic analyzer calculated the product value of the ethanol and DDGS as 0.87 USD/litre and 0.37 USD/kg, respectively. Through cost sensitivity analysis results, it is identified that the ethanol selling price and the grain buying price have significant effects on the plant economy and it is confirmed that they are the main factors playing on the plant profitability in the base case model.The results of the alternative retrofits clearly demonstrate the importance of higher ethanol tolerant strains in ethanol production, which showed a less payback period compared to the base case. The payback periods of all the cases are showing the following patterns from the least to the highest: Retrofit 2 (17%) > Base case > Retrofit 3 > Retrofit 2 (4%) > Retrofit 1.Further retrofitting analysis results also suggested that using the stillage for biogas production will help in reducing the energy costs of the plant. The energy consumption of all the retrofits in ascending manner is as follows: Retrofit 3 > Retrofit 2 (17%) > Base case > Retrofit 1 > Retrofit 2 (4%). The energy usage result comparison of all the cases shows that, in third retrofit the overall energy consumption is decreased by 40% than the base case model.

The use of Fibre Reinforced Polymers (FRP) has grown in popularity in the construction industry. FRP has proven useful in the retrofit of various types of structural elements. It may be used for the strengthening of beams, the seismic upgrade of walls panels, as well as the jacketing of columns to provide confinement. There exist several methods of FRP application for the case of structural retrofits. These include the application of pre-prepared FRP mats, or application of FRP via the wet lay-up process. However, a new technique developed at the University of British Columbia allows for the application of FRP in the form of a spray. Externally bonded Sprayed FRP (SFRP) is known to increase strength and energy absorption capacity of a retrofitted member as well as, or better than, FRP sheets. However, tests have primarily been carried out on concrete members only. An area of interest, into which not much research has been conducted, is the application of SFRP to timber. Timber bridges are extensively used in many parts of the world. Often due to remoteness and practical constraints, it is impossible to apply FRP sheets to retrofit these bridges. SFRP would be a much easier method of FRP application. This study looked at the application of SFRP to Douglas Fir (D.Fir) Beam specimens subjected to 3-Point Flexural Loading only. The specimens were treated with either a water based (Borocol) or oil borne (Creosote) antifungal preservative prior to being sprayed with FRP. Different combinations of adhesives/bonding agents including Hydroxymethylated Resorcinol and Polymeric Isocyanates were used to try to develop a strong bond. When considering using only chemical adhesives to obtain a proper bond between the two constituents of the composite, use of HMR is recommended for timber which is untreated or has been treated with a water borne preservative such as Borocol, while a pMDI adhesive such as AtPrime 2 is recommended for timber treated with an oil borne preservative such as Creosote. For Non Creosoted beams, adhesives did not generate as significant of a strength gain. For Creosoted beams, adhesives may be sufficient to generate significant strength gain when SFRP is applied to a beam. Considering that most structures in use would probably have been treated with a preservative similar to Creosote, in practice, AtPrime 2 or some other some sort of pMDI would probably be the adhesive of choice. Based on the results of the study, it is possible to say that the application of SFRP to retrofit/rehabilitate timber structures shows considerable promise. If a decent bond is achieved between the composite constituents, it is possible to substantially increase the ultimate flexural strength of the member, as well as drastically increase its ductility and energy absorption capacity. It is recommended that further tests be carried out using different types of loading schemes, geometrical configurations of SFRP, other types of anchorage, and development of a proper analytical model before the method is adopted for widespread use.