Download or read book Numerical Simulation of Strengthened Unreinforced Masonry URM Walls by New Retrofitting Technologies for Blast Loading written by Yu Su and published by . This book was released on 2008 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This project was carried out to find efficient retrofitting technique under blast loading by developing numerical material models. It was based on experimental research of strengthening URM walls by using retrofitting technologies under out-of-plane loading at the University of Adelaide. The numerical models can be applied to study large-scaled structures under static loading, and the research work is then extended to the field of blast loading. To study the increasing capability in strength and ductility of retrofitted URM walls, pull-tests were simulated using interface element model to investigate the bond-slip relationship of FRP plates bonded to masonry blocks. The interface element model was then used to simulate performance of retrofitted URM walls under static loads. The accuracy of the numerical results was verified by comparing with the experimental results from previous tests at the University of Adelaide by Griffith et al. (2007) on unreinforced masonry walls and by Yang (2007) on FRP retrofitted masonry walls. To study the de-bonding behaviours of retrofits bonded to masonry, and find appropriate solution to protect certain masonry walls against blast loading, various retrofitting technologies were examined. The simulation covers explosive impacts of a wide range of impulses. Based on this work, pressure-impulse diagrams for different types of retrofitted URM walls were developed as a design guideline for estimating the blast effect on retrofitted masonry walls." -- From abstract.

Download or read book Blast Retrofit of Unreinforced Masonry Walls Using Fabric Reinforced Cementitious Matrix FRCM Composites written by Hyunchul Jung and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Unreinforced masonry (URM) walls are commonly found in existing and heritage buildings in Canada, either as infill or load-bearing walls. Such walls are vulnerable to sudden and brittle failure under blast loads due to their insufficient out-of-plane strength. The failure of such walls under blast pressures can also result in fragmentation and wall debris which can injure building occupants. Over the years, researchers have conducted experimental tests to evaluate the structural behaviour of unreinforced masonry walls under out-of-plane loading. Various strengthening methods have been proposed, including the use of concrete overlays, polyurea coatings and advanced fiber-reinforced polymer (FRP) composites. Fabric-reinforced cementitious matrix (FRCM) is an emerging material which can also be used to strengthen and remove the deficiencies in unreinforced masonry walls. This composite material consists of a sequence of one or multiple layers of cement-based mortar reinforced with an open mesh of dry fibers (fabric). This thesis presents an experimental and analytical study which investigates the effectiveness of using FRCM composites to improve the out-of-plane resistance of URM walls when subjected to blast loading. As part of the experimental program, two large-scale URM masonry walls were constructed and strengthened with the 3-plies of unidirectional carbon FRCM retrofit. The specimens included one infill concrete masonry (CMU) wall, and one load-bearing stone wall. The University of Ottawa Shock Tube was used to test the walls under gradually increasing blast pressures until failure, and the results were compared to those of control (un-retrofitted) walls tested in previous research. Overall, the FRCM strengthening method was found to be a promising retrofit technique to increase the blast resistance of unreinforced masonry walls. In particular, the retrofit was effective in increasing the out-of-plane strength, stiffness and ultimate blast capacity of the walls, while delaying brittle failure and reducing fragmentation. As part of the analytical research, Single Degree of Freedom (SDOF) analysis was performed to predict the blast behaviour of the stone load-bearing retrofit wall. This was done by computing wall flexural strength using Plane Section Analysis, and developing an idealized resistance curve for use in the SDOF analysis. Overall, the dynamic analysis results were found to be in reasonable agreement with the experimental maximum displacements.

Download or read book Blast Simulator Wall Tests written by Michael G. Oesterle and published by . This book was released on 2009 with total page 655 pages. Available in PDF, EPUB and Kindle. Book excerpt: Loads generated in explosions that result from terrorist attacks and industrial accidents create devastating hazards for buildings and their occupants. The objective of this dissertation is to develop design guidelines and methodologies for protective/hardening strategies used to mitigate blast hazards in reinforced concrete and concrete masonry walls. Commonly, guidelines and methodologies are developed from experimental data. Field testing with live explosive is a reliable experimental method for demonstrating the performance of blast resistant concepts, but it is expensive, time consuming, and often produces low quality data. Static testing is another experimental method that allows researchers to clearly observe behavior and failure modes of structural components; however this too is limited because it cannot account for the rate effects associated with blast loads. The UCSD Blast Simulator was developed to offers an alternative method for testing structures to loads generated in an explosion without the difficulties and limitations associated with field and static testing. For this dissertation, tests were conducted with the blast simulator to study reinforced concrete walls protected with frangible panels, concrete masonry walls strengthened with carbon fiber reinforced polymer composite, and unreinforced masonry walls retrofitted with polyurea catcher systems. The objective of the dissertation was achieved through a succession of tasks that included; the development of a test protocol, validation and implementation of numerical models to predict loads delivered to specimens during blast simulator tests, development of method to correlate blast simulator loads to air blast loads, generation of high quality data on specimens with mitigation strategies for validation of numerical models to predict response of hardened/protected reinforced concrete and concrete masonry walls, and investigation of design variables with parametric studies. The investigation of concrete masonry walls demonstrated that the addition of carbon fiber reinforced polymers can increase the resistance to blast loads, but may result in a brittle failure mode. The study of reinforced concrete walls showed that frangible panels can improve the response by adding mass to the system. Finally, the research performed on unreinforced masonry walls with polyurea catcher emphasized the need for proper connection detailing.

Download or read book Blast Protection of Civil Infrastructures and Vehicles Using Composites written by Nasim Uddin and published by Elsevier. This book was released on 2010-03-12 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the upsurge in terrorism in recent years and the possibility of accidental blast threats, there is growing interest in manufacturing blast 'hardened' structures and retrofitting blast mitigation materials to existing structures. Composites provide the ideal material for blast protection as they can be engineered to give different levels of protection by varying the reinforcements and matrices.Part one discusses general technical issues with chapters on topics such as blast threats and types of blast damage, processing polymer matrix composites for blast protection, standards and specifications for composite blast protection materials, high energy absorbing composite materials for blast resistant design, modelling the blast response of hybrid laminated composite plates and the response of composite panels to blast wave pressure loadings. Part two reviews applications including ceramic matrix composites for ballistic protection of vehicles and personnel, using composites to protect military vehicles from mine blasts, blast protection of buildings using FRP matrix composites, using composites in blast resistant walls for offshore, naval and defence related structures, using composites to improve the blast resistance of columns in buildings, retrofitting using fibre reinforced polymer composites for blast protection of buildings and retrofitting to improve the blast response of concrete masonry walls.With its distinguished editor and team of expert contributors, Blast protection of civil infrastructures and vehicles using composites is a standard reference for all those concerned with protecting structures from the effects of blasts in both the civil and military sectors. - Reviews the role of composites in blast protection with an examination of technical issues, applications of composites and ceramic matrix composites - Presents numerical examples of simplified blast load computation and an overview of the basics of high explosives includes important properties and physical forms - Varying applications of composites for protection are explored including military and non-military vehicles and increased resistance in building columns and masonry walls

Download or read book Blast Retrofit of Unreinforced Masonry Walls Using ECC Shotcrete written by Jordan Gandia and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Boundary Connection Behavior and Connection Design for Retrofitted Unreinforced Masonry Walls Subjected to Blast Loads Preprint written by and published by . This book was released on 2010 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past decade, extensive experimental and analytical research has been conducted on the behavior and resistance of unreinforced masonry (URM) walls retrofitted with methods for increasing ductility. This includes numerous experiments conducted by the Airbase Technologies Division of the Air Force Research Laboratory (AFRL). These retrofit materials varied from soft elastomeric coatings to very stiff composites and metal sheets. Some retrofit materials were strongly bonded to the masonry wall, which resulted in an integrated system response, while others were not bonded to the masonry and the membrane simply acted as a barrier that prevented secondary fragmentation from entering the occupied space. Previous research programs by AFRL and others have focused on the development of the retrofit materials, with the predominant exploratory measure focusing on the maximum inward transverse displacement. However, little emphasis was placed on the real behavior of the boundaries of these systems and the proper and efficient design of connections. This paper discusses an appropriate analytical methodology for the design of retrofit connections to resist impulse loads due to blast. In addition, typical support conditions for URM walls, and the shear, flexure and friction interaction of blast-impulse-loaded retrofitted URM walls at their support boundaries are discussed. The ideas and conclusions presented herein are based on component-level static testing, full scale explosion arena testing, and high fidelity finite element modeling.

Download or read book Retrofitting of Unreinforced Masonry Walls Using Fiber Reinforced Polymer Laminates written by Reid Robert Senescu and published by . This book was released on 2004 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Strengthening of Reinforced Masonry Walls Subjected to Out of plane Pseudo static Cyclic Load Using Advanced Composite written by Zuhair Al-Jaberi and published by . This book was released on 2018 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: "A number of researchers have conducted experimental tests on unreinforced masonry walls (URM) strengthened with advanced composite materials. Consequently, the strengthening design guidelines are limited in their scope to URM. This research aimed to investigate the behavior of reinforced masonry walls strengthened with advanced composite and subjected to out-of-plane pseudo-static cyclic load. Experimental and analytical studies were conducted to evaluate the performance of different techniques such as near surface mounted (NSM) and externally bonded (EB) fiber reinforced polymer (FRP) with epoxy resin, in addition to NSM with cementitious adhesive and fiber reinforced cementitious material (FRCM). The experimental part included three phases. In the first phase, a series of 42 reinforced masonry walls were tested to study the effectiveness of advanced composites in enhancing out-of-plane flexural capacity. The effect of long-term environmental exposure on strengthening systems was investigated in the second phase of study by testing 10 reinforced masonry walls. The third phase focused on bond behavior between the advanced composite and the concrete masonry unit at different temperatures; 56 specimens were used for this purpose. The results indicated that the non-arching strengthened reinforced masonry wall's behavior was significantly dependent on the type of fiber and fiber reinforcement ratio. The specimens strengthened with glass under combined environmental cycles exhibited an insignificant change in terms of ultimate strength as compared to laboratory conditioned specimens. The theoretical part included the investigation of bond reduction factors, seismic performance, and the nonlinear analysis of strengthened reinforced masonry wall using moment-curvature analysis. As a result of this study, the proposed model for predicting debonding strain and the moment-curvature relation presented an excellent prediction compared to the experimental results"--Abstract, page iv.

Download or read book Performance of Polyurea Retrofitted Unreinforced Concrete Masonry Walls Under Blast Loading written by Laura Ciornei and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Unreinforced masonry walls subjected to blast loading are vulnerable to collapse and fragmentation. The objective of this thesis is to conduct experimental and analytical research for developing a blast retrofit methodology that utilizes polyurea. A total of four unreinforced masonry walls were constructed and tested under various shock tube induced blast pressures at the University of Ottawa Shock Tube Testing Facility. Two of the retrofitted walls had surface-sprayed polyurea. The results indicate that the use of polyurea effectively controlled fragmentation while significantly increased the load capacity and stiffness of masonry walls. Polyurea proved to be an excellent retrofit material for dissipating blast induced energy by providing ductility to the system and changing the failure mode from brittle to ductile. Single degree of freedom (SDOF) dynamic analyses were conducted as part of the analytical investigation. The results show that the analytical model provides reasonably accurate predictions of the specimen response.

Download or read book Resilient Infrastructure written by Sreevalsa Kolathayar and published by Springer Nature. This book was released on 2021-10-28 with total page 509 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the select proceedings of the Virtual Conference on Disaster Risk Reduction (VCDRR 2021). This book discusses various relevant topics such as Disaster resilience and Infrastructure, Risk reduction and structural measures, Evidence based approach for DRR Case studies, Numerical modelling and Constructions methods, Prevention Methods and Safety Engineering, Cross cutting issue in DRR and Infrastructure etc. The book is also a comprehensive volume on multi-hazards and their management for a sustainable built environment. This book will be useful for academicians, research scholars and industry professionals working in the area of civil engineering and disaster management.

Download or read book Critical Infrastructure Protection written by L. Kruszka and published by IOS Press. This book was released on 2019-05-10 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent decades have seen an increase in the number of terrorist attacks, necessitating the development of more efficient global security policies. One of the most important elements of this enhanced security is the protection of critical infrastructure. This book presents edited contributions from the NATO Advanced Training Course (ATC) on Critical Infrastructure Protection - Best Practices and Innovative Methods of Protection, held in Agadir, Morocco, from 6 to 12 May 2018. The main objective of the course was to bring together specialists working in the area of protecting critical infrastructure in NATO Member and Partner countries to share their knowledge and expertise. One lecture block was dedicated to important legal aspects, as these differ from country to country. The other main topic areas included the structural design and protection of critical infrastructure, new materials and material analysis, and material and construction testing at elevated impact velocities via experiment and numerical simulation. New designs for critical infrastructure elements were also demonstrated. The course provided an ideal forum for speakers and participants from government, academia, and military bodies to exchange information and best practice, while at the same time creating links to foster further collaboration and the exchange of ideas about the protection of critical infrastructure, and the book will be of interest to all those whose work involves protecting critical infrastructure from the threat of terrorist attack.

Download or read book Fastenings for Seismic Retrofitting written by Comité euro-international du béton and published by Thomas Telford. This book was released on 1997 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: The economic consequences and loss of life make earthquake disasters catastrophic anywhere in the world. Seismic retrofitting, or repair, of buildings is an essential component for mitigating the effects of earthquakes. This state-of-the-art report reviews and introduces the latest design concepts and methods for seismic retrofitting throughout the world, with emphasis on the use of fastening systems.

Download or read book Structural Rehabilitation of Old Buildings written by Aníbal Costa and published by Springer Science & Business Media. This book was released on 2013-09-11 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: This present book describes the different construction systems and structural materials and elements within the main buildings typologies, and it analyses the particularities of each of them, including, at the end, general aspects concerning laboratory and in-situ testing, numerical modeling, vulnerability assessment and construction maintenance.

Download or read book Advances in Protective Structures Research written by Hong Hao and published by CRC Press. This book was released on 2012-08-17 with total page 409 pages. Available in PDF, EPUB and Kindle. Book excerpt: The International Association of Protective Structures (IAPS) was launched on 1 October 2010 in Manchester, UK during the first International Conference of Protective Structures. The primary purpose of IAPS is to bring researchers and engineers working in the area of protective structures together, and to promote research and development work for b

Download or read book Numerical Modeling of Masonry and Historical Structures written by Bahman Ghiassi and published by Woodhead Publishing. This book was released on 2019-06-15 with total page 819 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical Modeling of Masonry and Historical Structures: From Theory to Application provides detailed information on the theoretical background and practical guidelines for numerical modeling of unreinforced and reinforced (strengthened) masonry and historical structures. The book consists of four main sections, covering seismic vulnerability analysis of masonry and historical structures, numerical modeling of unreinforced masonry, numerical modeling of FRP-strengthened masonry, and numerical modeling of TRM-strengthened masonry. Each section reflects the theoretical background and current state-of-the art, providing practical guidelines for simulations and the use of input parameters. - Covers important issues relating to advanced methodologies for the seismic vulnerability assessment of masonry and historical structures - Focuses on modeling techniques used for the nonlinear analysis of unreinforced masonry and strengthened masonry structures - Follows a theory to practice approach

Download or read book Mechanics of Masonry Structures written by Maurizio Angelillo and published by Springer Science & Business Media. This book was released on 2014-03-20 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: The experience of people working with different perspectives in different fields of masonry modeling, from mathematics to applied engineering and practice, is brought together in this book. It presents both the theoretical background and an overview of the state-of-the-art in static and dynamic masonry modeling.

Download or read book The Dynamics of Explosion and Its Use written by Josef Henrych and published by Elsevier Science & Technology. This book was released on 1979 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt: