Reinforced Masonry Structures Research Articles

Experimental investigation of effect of section configuration on seismic performance of an innovative integrated concrete masonry wall system

Abstract In this study, an innovative integrated concrete masonry wall (ICMW) system is proposed to improve the seismic behavior of infill masonry in reinforced masonry structures. The ICMW system consists of a load-bearing component comprising two reinforced concrete masonry walls and a partition component comprising one ungrouted masonry wall and autoclaved aerated concrete blocks. Four ICMW specimens were designed for cyclic loading test and the effects of the section type of the load-bearing component and infill on the seismic performance of the specimens were investigated. An obvious pinching effect was observed on the load-displacement curves of all specimens. Different flexural and shear failure modes occurred in the specimens due to the section type of the load-bearing components, whereas the infill heightened the crack propagation. The results indicated that the stiffness degradation, displacement ductility, energy dissipation, and equivalent viscous damping ratio of the specimens were obviously influenced by the section type owing to different failure modes. Moreover, it was observed that the infill had a beneficial influence on the ductility coefficient of the specimens because of its timely separation. Based on these results, it is concluded that the ICMW is an effective construction system in which the partition component participates in the specimen loading process at the initial stage and separates from the specimen to protect it and prevent out-of-plane damage at the final stage.

Comprehensive approach to the restoration of historical and cultural monuments (example of the mansion of A. A. Polovtsov)

The article deals with the problems of restoration design and study of cultural heritage objects that have a long history of existence and operation since the first half of the 19th century. The main aspects faced by researchers of monuments in our time are listed. The list of problems that designers face when studying such objects in St. Petersburg is given. A small dive into the technology of historical development for 250-300 years in St. Petersburg is made. The features of historic masonry and reinforced masonry structures are discussed. In particular, the problems of the state of brickwork walls of cultural heritage monuments of the early 19th century are listed. As a result, it can be stated that the technical and technological difficulties of restoration and the most problematic objects in the design were left to the current generation. We can also say that the current community of restoration designers, to a greater extent, does not take into account many factors that affect the integrity and load-bearing capacity of masonry historical walls. Using the example of a cultural heritage object - the building of the mansion of A. A. Polovtsov, the stages of design of restoration work and analysis of the result obtained and forced corrections after detailed restoration implementation in the structure during its restoration and conservation are given.

Increasing the Monolithic Nature of Masonry Made of Cellular Concrete Blocks by Using Polyurethane Foam Glue as a Masonry Mortar

This study is a continuation of previously published work [1]. The results of experimental determination of the strength of normal adhesion (under axial tension) in masonry made of autoclave–hardened cellular concrete blocks of compressive strength classes B1,5-B3,5 on cement mortars and polyurethane foam adhesives are presented. The tests were carried out in the laboratory of the Department “Reinforced Concrete and Stone Structures” of the Moscow State University of Civil Engineering (National Research University). The experiment was carried out on samples-cubes with a size of 150x150x150 mm, which were cut out of cellular concrete blocks, fastened (glued) together using masonry (binding) compositions. In the course of the study, it was found that when using various polyurethane foam glue compositions in masonry made of cellular concrete blocks of compressive strength classes B1,5–B3,5, the resistance to axial stretching over an unbound section (normal adhesion) of the masonry increases by approximately 9–25%. It was also found that the nature of the destruction of samples made on polyurethane foam adhesives (destruction occurs along the body of concrete), indicates the monolithic nature of the masonry. The analysis of the results obtained makes it possible to conclude that the resistance to axial tension along the unbound section of the masonry depends on the strength of the material from which the block is made, and not on the compressive strength of the masonry (binder) mortar used, as indicated in table 11 of SP 15.13330.2012 “Stone and reinforced masonry structures”. This factor must be taken into account when calculating masonry from autoclave-hardened cellular concrete blocks on polyurethane foam compositions.

A fast modeling approach for numerical analysis of unreinforced and FRCM reinforced masonry walls under out-of-plane loading

A new discretized homogenization approach is proposed in this study in order to predict the behavior of unreinforced and FRCM reinforced masonry structures. The proposed approach allows overcoming the common disadvantages of the existing homogenization approaches: (a) being difficult to implement and (b) not allowing to couple the in-plane and out-of-plane actions. Reference experimental results and detailed numerical modeling are used for validation of the proposed modeling strategy. In the proposed model, the elastic cells are linked by homogenized interfaces. The mechanical properties coming from the homogenization procedures are lumped at the interfaces by means of the generic Concrete Damage Plasticity model, allowing easy implementation and avoiding computational issues peculiar to other approaches available in the literature. The new approach shows accurate results in predicting the global behavior and the damage pattern for both unreinforced and FRCM strengthened masonry walls. The results are promising also with a view to be applied for more complex reinforced applications as double curvature masonry structures.

Composite Materials with Natural Fiber NFRC on Inorganic Matrix for Seismic Reinforcement of Masonry Structures

Composite materials with carbon, aramidic, glass and lately basalt fibers with a polymeric or cementitious matrix FRP or FRC, are frequently used for the seismic reinforcement of masonry buildings. The fibers of such composites are synthetic, and they have high mechanical characteristics. However, their cost is very expensive and do not belong to the eco compatible products. Moreover, for the making of these fibers an elevated amount of energy is needed for reaching the temperature relative to the production process.An alternative to the use of such fibers may be recurring to natural eco compatible fibers for which the cost is much lower, and they do not need a special processing. Using such fibers in an inorganic cementitious matrix, an improvement of the mortar or of the plaster quality is obtained, giving to them also an adequate ductility.In order to make the composite material, short fibers immersed in the cementitious mortar are used; the composite material can be represented using the acronym NFRC (Natural Fiber Reinforced Composite).Among the different types of fibers that can be used, there is the short fibers derivate from the bamboo plant that are available under the form of yarns or threads.The scope of this paper consists in the definition of the optimal volumetric ratio for the NFRC composite, and the length of the fiber compatible with the workability and the resulting mechanical characteristic.

FRP Pultruded Material as Reinforcement for Masonry: Expected Interaction in the Medium and Long Time

Masonry buildings are still very common in the area with high seismic zone, such as the Mediterranean countries and other areas of the world recently hit by earthquakes of considerable intensity. The structural reinforcement of the masonry load-bearing elements is often necessary to increase their seismic resistance, also underway to modern regulatory codes. The use of FRP materials (fiber-reinforced polymers), produced by the pultrusion process, is for these purposes of a possible solutions. FRP pultruded structural elements could enhance the seismic capacity of the reinforced masonry structure and represent an advantage. The application of these materials in the field of structural reinforcement, takes place by gluing with appropriate adhesives or by bolting on the element to be reinforced. The aim of our research is the evaluation of the life cycle (LCA) of FRP glued a halted to the masonry. In detail, the research shows the final experimental results, related to the residual mechanical performance of pultruded samples subject to induced aging.

Structural Failure Analysis of Earthquake Affected Buildings in Gorkha (Nepal) Earthquake 2015 in Kathmandu Valley

The major earthquake in April 25, 2015 of Mw 7.8 and aftershock of intensity Mw 7.3 on May 12, 2015 has caused not only a substantial death toll and huge economic losses, but also heavy damage to many buildings. This paper outlines the common observed damage patterns of different types of buildings in Kathmandu valley induced by the earthquake and their constructional deficiencies..We visited Department Of Urban Development and Building Construction (DUDBC) of Nepal Government, and Nepal Society for Earthquake Technology (NSET) and got various information regarding structural damages caused by Gorkha earthquake. After acquiring knowledge on this topic through internet and from NSET and DUDBC, the structural failure analysis of buildings affected during the earthquake in Kathmandu Valley was done by photo observation. Both unreinforced masonry buildings and reinforced masonry structures suffered low to heavy destruction. The construction and structural deficiencies were identified to be the major cause of failure, however local soil amplification, foundation problems, liquefaction associated damages and local settlement related damages were also significantly observed during this earthquake and reported in the paper. The Gorkha earthquake sequences delivered unprecedented opportunity to augment the understanding on seismic performance of the buildings. This paper is also motivated to point out the faintness in the past to current constructional practice of buildings, provide preventive measure and convey awareness to stake holders for future safer building construction practice.

Investigation on Mechanical Properties of Masonry Infill Wall Strengthened with ECC

Engineered Cementitious Composite (ECC) is an advanced composite material with strain-hardening and multiple-cracking behaviors. In this study, two types of ECC materials were troweled on masonry infill walls strengthened with expansion bolt and interfacial agent. The seismic performance of the unreinforced and the ECC reinforced masonry structures was evaluated by the reversed cyclic loading test. The results showed that the application of the ECC on the masonry infill walls can improve the ultimate bearing capacity (in plane), ductility, stiffness and accumulative energy dissipation of the structure. Compared with the masonry structure with one side reinforced by the ECC, the structure with both sides reinforced by the ECC could better improve the ultimate bearing capacity, stiffness and cumulative energy dissipation with little difference on the ductility improvement. Moreover, the expansion bolt and the interfacial agent used to improve the connection between the ECC and the masonry structure have the ability to greatly increase the mechanical properties of the structure under cyclic loading.

Investigation of seismic performance of in-plane aligned masonry panels strengthened with Carbon Fiber Reinforced Polymer

Masonry structures are economical, easy to construct and has important advantages such as the use of natural materials. In Turkey, these structures have been heavily built especially with traditional construction methods and nowadays they are popular as well. Therefore, the reinforcement of masonry structures and seismic safety are of paramount importance. Masonry walls are not naturally stable and cannot be considered as homogeneous structures so it is difficult to predict their behavior under load by using numerical methods. Supportive framework of the mathematical model and the data of the experimental studies are required. In this study, 36 wall blocks were prepared in 900 × 900 × 200 mm using hollow masonry brick, blend brick and aerated concrete and these blocks are reinforced with Carbon Fiber Reinforced Polymer in both directions by using three different methods. For the analysis of retrofit brick walls produced and reinforced with different materials, ASTM E591 test method was used. At the end of the experiment period; shear strength performances of the reinforcement methods of the elements, their deformation and energy dissipation capacities were evaluated. According to results, maximum shear strength performance was observed at the masonry panel strengthened by two face. Maximum load value was 172.63 Kn. Also maximum dissipation capacity was observed at the masonry wall reinforced with CFRP covered diagonally. Maximum energy dissipation capacity was 317.1 J.

On the effectiveness of CFRP reinforcement of masonry panels loaded by out-of-plane actions

The use of composite materials, in particular Carbon Fiber Reinforced Polymers (CFRP), as reinforcement of masonry structures is more and more widespread in the structural rehabilitation and retrofitting of existing buildings. Several research findings reported in the literature demonstrated that externally bonded CFRP sheets can effectively increase the mechanical performance of masonry walls subjected to both in-plane and out-of-plane actions. Concerning the latter, most research activities refer to monotonic actions. Seeing the lack in the literature, the experimental program described in this paper is aimed to the analysis of the effects of load cycles in the out-of-plane behavior of reinforced masonry walls.

The Feasibility Study on Application of Fiberglass Grids in Masonry Structure

Based on the analysis of the research status of reinforced masonry in China and abroad, the shortcomings of reinforced masonry structure in China are put forward. By analyzed the advantages of fiber grid materials in masonry structure and the research status of fiber grid in China and abroad, the new system of fiberglass reinforced masonry instead of reinforced masonry is proposed, which makes up the shortage of reinforced masonry and conducive to the development of wall material innovation and building energy conservation. Some suggestions are put forward for the research of the new system of fiberglass reinforced masonry structure, which has a good practical significance and broad application prospects.

Seismic vulnerability assessment of residential buildings using logistic regression and geographic information system (GIS) in Pleret Sub District (Yogyakarta, Indonesia)

BackgroundThe Southeast of Yogyakarta City has had the heaviest damages to buildings in the 2006 of Yogyakarta Earthquake disaster. A moderate to strong earthquake of 6.3 Mw shook the 20 km southeast part of the Yogyakarta City early in the morning at 5:54 local time. On top of extensive damage in Yogyakarta and Central Java, more than 5700 people perished; 37,927 people were injured in the collapse of more than 240,396 residential buildings. Furthermore, the earthquake also affected the infrastructure and local economic activities. The total damages and losses because of the earthquake was 29.1 trillion rupiahs or equal to approximately 3.1 million US dollar. Two main factors that caused the severe damages were a dense population and the lack of seismic design of residential buildings. After reconstruction and rehabilitation, the area where the study was conducted grew into a densely populated area. This urbanistic change is feared to be potentially the lead to a great disaster if an earthquake occurs again. Thus, a comprehensive study about building vulnerability is absolutely needed in study area. Therefore, the main objective of this study has been the provision of a probabilistic model of seismic building vulnerability based on the damage data of the last big earthquake. By considering the relationship between building characteristics, site conditions, and the damage level based on probabilistic analysis, this study can offer a better understanding of earthquake damage estimation for residential building in Java.ResultsThe main findings of this study were as follows: The most vulnerable building type is the reinforced masonry structure with clay tile roof, it is located between 8.1-10 km of the epicentre and it is built on young Merapi volcanic deposits. On the contrary, the safest building type is the houses which has characteristics of reinforced masonry structure, asbestos or zinc roof type, and being located in Semilir Formation. The results showed that the building damage probability provided a high accuracy of prediction about 75.81%.ConclusionsThe results explain the prediction of building vulnerability based on the building damaged of the Yogyakarta earthquake 2006. This study is suitable for preliminary study at the region scale. Thus, the site investigation still needs to be conducted for the future research to determine the safety and vulnerability of residential building.

Weighting Assessment of Vulnerability Index Parameters for Reinforced Masonry Structures

The ancient Algerian urban nuclei are composed of different kind of structural systems, such as unreinforced masonry building (URM) buildings, reinforced concrete (RC) buildings, steel buildings and last but not the least the reinforced masonry structures. This type of structure is one of the most vulnerable to seismic action, as they were not built to seismic codes and regulations. In this paper, a contribution for the safety assessment of reinforced masonry buildings under seismic loading is presented. With this purpose, a vulnerability index method has been applied to this type of buildings for the Algerian case according to the national seismic regulations (RPA), by identifying the most important parameters that have an influence on the seismic behaviour of such structures. Weighting factors are then assigned to each parameter in order to evaluate the vulnerability index, which allows classifying each assessed structure according to a suggested classification. The weighting factors were first estimated by a dynamic analysis using ten seismic records. Lastly this method was implemented in a Delphi program and performed using several examples to show its efficiency.

Assessment of seismic damage to buildings in resilient Byblos City

Byblos, one of the oldest continuously inhabited cities in the world and a UNESCO World Heritage Site, is indeed a resilient city that has thrived for more than 7000 years while mitigating shocks and stresses. Byblos, at the threshold of the 21st century, is still adapting, growing and changing. In this paper, aiming to bridge between international heritage resilience and disaster risk management: first, the resilience of international heritage is discussed in general and resilience qualities of Byblos in particular; second earthquakes, one of the main threats faced by Byblos is identified; and third the earthquake damage to Byblos buildings is assessed by mean of different likely earthquake scenarios. For that purpose, data for Byblos building inventory have been gathered through a ground survey. The earthquake hazard for the region has been defined, hazard maps have been digitized, and structural vulnerability functions were assigned. After preparation of the needed files using the Geographic Information System, the Ergo platform was used to model the earthquake-induced building damage. It was obtained that the unreinforced masonry structure type is the most vulnerable to earthquakes, the reinforced masonry structures type is the second most vulnerable, followed by reinforced concrete frame structures, and finally by reinforced concrete frames with shear walls structures. It was recommended to upgrade, whenever possible, the unreinforced masonry buildings to reinforced masonry buildings while preserving their historical aspect, and to strengthen the frame concrete buildings by adding shear walls whenever possible. All new buildings to be constructed in the future are recommended to strictly follow the codes. This study helps to gain a better understanding of the extent of potential damage; it allows establishing an earthquake preparedness strategy and recovery plan to enhance the resilience of the city.

Displacement-Based Seismic Design for Reinforced Masonry Shear-Wall Structures, Part 2: Validation with Shake-Table Tests

This paper provides a comprehensive validation of a displacement-based seismic design procedure proposed in a companion paper for reinforced masonry shear-wall structures. For this purpose, a full-scale, two-story reinforced masonry specimen was tested on a shake table to examine the global and local behaviors of a low-rise reinforced masonry building designed by the proposed displacement-based procedure, and to validate the analytical tool used in the design process. This specimen successfully resisted repeated ground motions with intensities up to the maximum considered earthquake (MCE). Its performance on the shake-table demonstrates that a reinforced masonry structure designed, detailed, and constructed according to the proposed displacement-based design procedure can resist MCE earthquakes without collapse even though it may suffer severe damage. In critical regions of this specimen, elements detailed in accordance with displacement-based requirements showed more inelastic deformation capacity than the deformation limits imposed by the displacement-based design provisions proposed here. The proposed procedure produces structures that behave according to design expectations, even though severely damaged.

Calibration of end-debonding strength model for FRP-reinforced masonry

The adherence between Fiber Reinforced Polymers (FRP) reinforcements and masonry is investigated in this paper. Debonding is, in fact, one of the dominant failure modes in the reinforcement of masonry structures by means of FRP materials. Relationships are proposed in design recommendations in order to evaluate the debonding load on the basis of the fracture energy concept. Corrective coefficients are also suggested in order to take into account the effect of bond length and width on the bond strength. In this work experimental double lap push–pull shear tests results are first presented and combined with experimental outcomes from the literature in order to create an enlarged database. An analytical model for the load transfer mechanism between the reinforcement and the substrate is then proposed. Besides, a refined fracture energy based model for the bond strength is suggested taking into account the effect of bond length and width. The experimental outcomes are first used to validate the analytical model for the load transfer mechanism. The enlarged database is then analyzed to achieve a refined statistical calibration of the experimental coefficients of the bond strength model and to highlight the variation of the maximum transmitted force with respect to mechanical properties of the substrate.

Experimental Study of Bond Behavior of CFRP-to-Brick Joints

AbstractCarbon fiber–reinforced polymer (CFRP) composite materials have been widely used to strengthen masonry constructions. The bond between CFRP and substrate strongly conditions the performance of reinforced masonry structures. Characterization of shear bond mechanical behavior of masonry-CFRP interface thus becomes a crucial factor. The paper presents the results of an extensive experimental investigation aimed at evaluating the bond between clay brick and CFRP sheet. Specimens with varying width and length of the bonded CFRP sheet were subjected to shear test by three different testing setups. Results allowed comparison of the effectiveness of the three types of setup and pointed out the influence of the dimensions of the bonded sheet on ultimate load and ultimate slip, load-displacement diagram, and failure modes. Measurement of local strain along the CFRP sheet also allowed an investigation on the transfer mode of the stresses from the reinforcement to the brick and the determination of the local ...

Digital Image Correlation Analysis of CFRP to Brick Bonded Joints Fastened by Fiber Anchor

In the framework of the reinforcement of masonry structures by FRP sheets (Fiber Reinforced Polymer), the use of “Fiber Anchor” is an innovative performing solution to increase the peak load and the dissipation capability of the strengthened system. To analyze the performance of this new technology an experimental campaign composed by 36 tests has been conducted. Six series of CFRP to brick bonded joint fastened by different configurations of fiber anchor have been tested. To deeply describe the measure fields, the Digital Image Correlation (DIC) has been used. The strain fields obtained in the series not fastened by anchors have permitted to define the bond stress field and the advancement of the stress transfer zone. The DIC appears as a performing methodology to use in a lot of civil engineering experimental problems.

Reinforced masonry in Europe – Working strategy for the preparation of the State of the Art Report / Bewehrtes Mauerwerk in Europa – Arbeitsstrategie für die Erstellung des State‐of‐the‐Art‐Reports

AbstractThe behaviour of reinforced masonry structures, especially when reinforcement is provided to enhance the mechanical properties, i.e. different strength types or resistance of masonry, is still not completely investigated or thoroughly understood. A significant lack of knowledge can be observed in many areas, especially in Europe. As a result of this situation, the Commission W023 – Wall Structures of the International Council for Research and Innovation in Building and Construction (CIB) set up a Working Group (WG5) – Reinforced and Prestressed Masonry a few years ago, of which the authors are convenors. The first task of the WG5 is to produce a State of the Art document covering reinforced masonry applications in order to identify topics for future research and development. This document will serve as a contribution for the revision of European Structural Masonry Code EN 1996‐1‐1:2005 (Eurocode 6) [1], which is planned to be done between 2015 and 2018. It was agreed at the last W023 Commission Meeting held in Eindhoven in October 2013 that the preparation of the State of the Art document should cover the specific experience and problems connected with reinforced and prestressed masonry structures under static and dynamic/seismic loading, also outside Europe. The process of preparing such a report is now underway and the following article describes the planned scope of the document.

Some Primary and Secondary School Building of Masonry Structure Seismic Reinforcement of Key Technical Discussion

In view of the common primary and secondary school teaching buildings (including library) that are masonry structure, and discussed the key technology of the reinforced masonry structure seismic, including mesh reinforcement cement mortar reinforced wall, cantilever beam end set column, design method and construction points of adding staircase column. This technology could provide reference for other similar seismic strengthening engineering.