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 Increasing the Blast Resistance of Concrete Masonry Walls Using Fabric Reinforced Cementitious Matrix FRCM Composites written by Ramon Perez Garcia and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Unreinforced masonry (URM) walls are often used as load-bearing or infill walls in buildings in many countries. Such walls are also commonly found in existing and heritage buildings in Canada. URM walls are strong structural elements when subjected to axial loading, but are very vulnerable under out-of-plane loads. This type of loading may come from different sources , including seismic or blast events. When subjected to blast, wall elements experience large pressures on one of their faces due to the high pressure produced in the air when an explosion takes place. This wave of compressed air travels in a very short time and hits the wall causing immense stresses, which result in large shear and bending demands that may lead to wall failure, and the projection of debris at high velocities that can injure building occupants. This failure process is highly brittle due to the very low out-of-plane strength that characterize such walls. In the past years, many investigations have been carried out to enhance the structural behaviour of unreinforced masonry walls under out-of-plane loading. Different strengthening methods have been studied, which include the use of polyurea coatings, the application of advanced fiber-reinforced polymer (FRP) composites or the use of concrete overlays in combination with high performance reinforcement. Fabric-reinforced cementitious matrix (FRCM) is a new composite material that overcomes some of the drawbacks of FRP. This composite material consists of applying coatings which consist of one or more layers of cement-based mortar reinforced with a corresponding open mesh of dry fibers (fabric). This material has been studied as a strengthening technique to improve in-plane and out-of-plane capacity of existing URM walls as well as other structural elements, mostly under seismic actions. 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, three large-scale URM masonry walls were constructed and strengthened with 1,2 and 3 layers of FRCM using unidirectional carbon fabrics. In all cases the specimens were built as load-bearing concrete masonry (CMU) walls. To increase shear resistance, two of the walls were also grouted with a flowable self-compacting concrete (SCC) mortar. Blast tests were conducted using the University of Ottawa Shock Tube and the results are compared with control walls tested in previous research at the University of Ottawa. The experimental results show that the FRCM retrofit significantly improved the blast performance of the URM load-bearing walls, allowing for increased blast capacity and improved control of displacements. The performance of the retrofit was found to be dependent on the number of retrofit layers. As part of the analytical research, Single Degree of Freedom (SDOF) analysis was carried out to predict the blast behaviour of the strengthened walls. This was done by computing wall flexural strength using plane sectional analysis and developing idealized resistance curves for use in the SDOF analysis. In general, the analysis procedure is found to produce reasonably accurate results for both the resistance functions and wall mid-height displacements under blast loading.

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 Masonry Walls Strengthened with Fabric Reinforced Cementitious Matrix Composite Subjected to In Plane and Out of Plane Load written by Saman Babaeidarabad and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A natural evolution of ferrocement has been the replacement of the reinforcing steel with new composite materials. Not only has this addressed the issue of possible durability problems associated with steel corrosion, but has opened the possibility of using thin-section cementitious products as repair materials. Fabric-reinforced cementitious matrix (FRCM) is a class of composite systems that has recently emerged as an alternative to traditional retrofitting methods like fiber-reinforced polymers (FRP), steel plate bonding, section enlargement, and external post-tensioning for repairing and strengthening reinforced concrete (RC) and masonry structures. FRCM consists of a reinforcing phase (fabrics) embedded into a matrix (cementitious mortar) adhered to concrete or masonry structural members and acts as supplemental, externally-bonded reinforcement. The goal of this dissertation is to experimentally and analytically investigate the effectiveness of FRCM to retrofit existing masonry structures; to evaluate the flexural and shear capacity of FRCM walls; to develop structural design procedures; and, to compare FRCM and FRP externally strengthened masonry walls. The dissertation is articulated in three studies. The first study (Study 1) investigates masonry walls externally strengthened with FRCM subjected to diagonal compression; the second (Study 2) focuses on FRCM strengthened walls subjected to out-of-plane loading; and the third (Study 3) presents a comparison between experimental results in this research program and other research programs using FRP systems when the normalized shear or flexural capacity is related to a calibrated reinforcement ratio.

Download or read book Proceedings of the Canadian Society of Civil Engineering Annual Conference 2021 written by Scott Walbridge and published by Springer Nature. This book was released on 2022-05-23 with total page 689 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book comprises the proceedings of the Annual Conference of the Canadian Society of Civil Engineering 2021. The contents of this volume focus on specialty conferences in construction, environmental, hydrotechnical, materials, structures, transportation engineering, etc. This volume will prove a valuable resource for those in academia and industry.

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 Blast Resistance of Un reinforced Masonry Walls Retrofitted with Fiber Reinforced Polymers written by Khaled Aly El-Domiaty and published by . This book was released on 2002 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental characterization and modelling of textile reinforced masonry structures with the Equivalent frame method written by Rizzo, Stefania and published by KIT Scientific Publishing. This book was released on 2022-09-09 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: An innovative strengthening technique for the seismic retrofitting of masonry buildings is the fabric-reinforced cementitious matrix (FRCM). The system presented in this work is EQ-GRID, which consists of a multi-axial hybrid grid made of alkali-resistant glass and polypropylene fibres and a natural hydraulic lime mortar (NHL) as matrix. The results of the performed experimental campaign and the numerical modelling with the Equivalent frame method are presented and discussed in this work.

Download or read book Retrofitting of Unreinforced Masonry Walls Using Fiber Reinforced Polymer Laminates written by Khalid M. Mosalam and published by . This book was released on 2000 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: Compares the structural response of unretrofitted unreinforced masonry (URM) walls with URM walls retrofitted on one side with glass fiber reinforced polymer (FRP) laminates. Six walls were tested using the diagonal tension standard test procedures. In this investigation, 2 objectives are considered. 1) a comparison is made between the improvements in performance provided by retrofitting a single-wythe wall vs. that provided by retrofitting a triple-wythe wall. 2) the performance enhancement provided by the FRP is compared with 2 mortar-to-brick strength ratios.

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 Fabric Reinforced Cementitious Matrix FRCM Composites for Infrastructure Strengthening and Rehabilitation written by Diana Arboleda and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of alternative techniques for structural rehabilitation is of critical importance to the safety and preservation of the world's civil infrastructure. Fabric-reinforced cementitious matrix (FRCM) composite systems have emerged as a sustainable repair methodology suitable for infrastructure strengthening and rehabilitation, including historical restoration. To this end, an experimental program was undertaken to investigate the tensile characterization method used to determine the material properties needed for design and to evaluate its performance in aggressive environments. Two new FRCM composite systems were selected for this research, one with polyparaphenylene benzobisoxazole (PBO) fabric reinforcement intended for the strengthening of reinforced concrete (RC) structures and one with carbon fabric reinforcement for the strengthening of masonry structures. This work aims to advance the state of FRCM testing methodology and it is presented through three studies, with an introductory chapter which gives a brief overview of composites focusing on the classification of brittle matrix composites in order to provide a contextual field within which FRCM is differentiated. The first study investigates the tensile test method used to characterize FRCM material properties, specifically the gripping mechanism and the load transfer length. The second study explores the performance of FRCM exposed to aggressive environments. And the third study evaluates and compares strain measurement methodologies based on their ability to measure axial strain of FRCM under uniaxial tensile loading, and their setup requirements. The overreaching objective is to analyze, evaluate, and propose the critical test methodology for FRCM composite characterization to obtain necessary design parameters.

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 Mechanics of Masonry Structures Strengthened with Composite Materials IV written by Giovanni Castellazzi and published by Trans Tech Publications Ltd. This book was released on 2022-04-07 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: Selected peer-reviewed full text papers from the 7th International Conference on Mechanics of Masonry Structures Strengthened With Composite Materials (MuRiCo 7)

Download or read book Blast Resistance of Membrane Retrofit Unreinforced Masonry Walls with Flexible Connections written by Eric M. Gagnet and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Acceptance Criteria for Masonry and Concrete Strengthening Using Fabric reinforced Cementitious Matrix FRCM and Steel Reinforfed Grout SRG Composite Systems AC434 written by ICC Evaluation Service and published by . This book was released on 2016 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Concrete Masonry Wall Retrofit Systems for Blast Protection written by Carol Faye Johnson and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The increased threat against government and public facilities in the United States and abroad has highlighted the need to provide an economic and efficient method to retrofit existing conventional structures. Hollow, unreinforced, concrete masonry unit (CMU) infill walls, commonly used in reinforced concrete or steel framed structures, are particularly vulnerable to blast loads. Facilities that incorporate CMU walls must either be hardened or retrofitted for explosive events. Conventional retrofit techniques that focus on increasing the overall strength of the structure by adding steel or concrete are difficult to implement, time consuming, expensive, and in some cases, increase the debris hazard. The current research presents an alternative retrofit system for CMU walls that involves the application of an elastomeric material applied to the interior surface of the wall to prevent secondary debris in the form of CMU fragments from entering the structure when it is exposed to blast loads. The experimental program used to evaluate the alternative retrofit systems was divided into three phases. In Phase one, resistance functions for seven different retrofit systems were developed in 24 subscale static experiments. In Phase two, the structural response of the retrofit systems subjected to blast loads was evaluated in 25 subscale experiments. The final phase of the experimental program consisted of 18 full-scale high-explosive (HE) experiments used to validate the structural response observed in the subscale dynamic experiments. Data generated from the experimental program were used to develop a single-degree-of-freedom (SDOF) model to predict the mid-span deflection of the retrofitted CMU walls subjected to blast loads. The subscale resistance functions from Phase one were scaled and used in the SDOF model. The full-scale experimental results and the predicted results from the model were compared and the retrofit systems were ranked according to the qualitative and quantitative results obtained from the experimental and analytical research. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151905

Download or read book Mechanics of Masonry Structures Strengthened with Composite Materials III written by Angelo Di Tommaso and published by Trans Tech Publications Ltd. This book was released on 2019-08-16 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book collected from papers presented on the 6th International Conference on Mechanics of Masonry Structures Strengthened With Composite Materials (MuRiCo6, June 26-28, 2019, Bologna, Italy). The aim of this collection is to present and review the latest achievements in modelling, testing and controlling masonry structures strengthened with composite materials. The innovative strengthening apparatus here considered consists of composites with continuous fibres (carbon, steel, basalt, aramid, glass, PBO? etc.) reinforcing polymer or inorganic matrices. The special problems regarding the strengthening of monumental historic constructions, considering appropriate techniques in the domain of architecture structural conservation, are focused in many scientific articles authored by eminent scientists.