Brick Masonry Walls Research Articles

Drying of an aerogel-based coating system in Swedish climates: Field tests and simulations

Aerogel-based coating mortars (ACM-systems) introduce new solutions for energy-retrofit of uninsulated building envelopes, preserving their characteristics while minimizing the material thickness. However, when introducing new solutions, the long-term durability needs to be investigated. The hygrothermal (heat and moisture) performance is one aspect that needs to be secured. The aim of this study is to investigate the hygrothermal performance, with specific focus on moisture drying, of an ACM-system for external applications in Swedish climates. A field test was conducted where an ACM-system with 40 mm of ACM was applied on the exterior of a brick masonry wall partition. The temperature and relative humidity in the wall were monitored for 15 months. Furthermore, numerical hygrothermal simulations were used to predict the early stage drying and long-term performance of the ACM-system in four Swedish climates. The field measurements showed that the built-in moisture dried out after approximately 6 months, after which the ACM-system followed the variations in the surrounding climate for the remaining period. The simulations predicted that the early stage drying time ranged from 134 to 336 days, depending on climate and time of application. Furthermore, the elevated relative humidity in the ACM due to rainwater absorption resulted in an average thermal conductivity of up to 9 % above the rated value. Consequently, mitigating water absorption at the exterior is crucial for enhancing the long-term thermal performance in high rain load scenarios.

Failure mode dependent shear strength of unreinforced concrete brick masonry wall panels

This study conducted diagonal compression tests to propose the failure mode dependent shear strength for unreinforced concrete brick wall panels. The test variable was the bed-joint mortar mixing ratio. Six brick wall panels were manufactured for each variable, and finally thirty specimens were tested. The test results showed five failure modes in the unreinforced masonry wall panels: diagonal tension, combined, bed-joint sliding, toe crushing, and non-diagonal failure. Furthermore, the shear strength of unreinforced brick wall panels was highly dependent on the failure mode. Based on the test results, the shear strength is suggested according to each failure mode. Additionally, the shear modulus of concrete brick wall panels was suggested as half of the value presented in the current codes for masonry structures.

Lime-based plasters reinforced with hemp meshes for retrofitting masonry structures

The recent earthquakes in the Mediterranean area provoked serious damages and collapses to the built-up, including masonry buildings that represent the highest percentage of existing structures. The protection of the historical heritage to prevent economic and human losses is always accompanied by the compelling need of preserving the environment due to the increasing attention to the sustainability issue. In this framework, retrofit solutions already widespread and effective in the Seismic Engineering field can also be improved from an environmental point of view. In past years, one of the techniques most applied to masonry structures is the Fiber Reinforced Cementitious Matrix (FRCM), that is usually made of artificial fibres, such as steel, carbon, and glass, immersed into a matrix used to fix the reinforcing system to the structural support. The sustainability of this reinforcement kind can be improved by replacing artificial fibres with natural ones, such as hemp, that claims good mechanical properties and is carbon negative. The research aims at experimenting a retrofitting system, called Hemp-FRCM, that is made of a hemp mesh drowned in a lime matrix. The hemp fibres are preliminary subjected to tensile tests. Then, the Hemp-FRCM system is applied to a brick masonry wall tested under compressive loads. Finally, the adhesion capacity of the system to a Neapolitan yellow tuff support is evaluated by performing delamination tests. The experimental campaign shows promising results on the use of hemp meshes instead of artificial systems for the structural retrofit of existing masonry buildings.

A comparative LCA of external wall assemblies in context of Iranian market: considering embodied and operational energy through BIM application.

Building envelopes have a critical role in the sustainability of the construction sector. The goals of the current research are assessing the environmental impacts of typical exterior wall assemblies and presenting the best Iranian market option through taking account of both embodied and operational energy. Autodesk Green Building Studio (GBS) is used to determine the operating loads of each wall. Simapro, a life cycle assessment software, is applied for managing data on environmental impacts. The derived results demonstrate that human health is the most severe damage category for all the analyzed walls. Also, the end-of-life stage's environmental impact is insignificant compared to the production and use stages. Reducing carbon emissions has the highest priority, such that replacing 1 m2 of masonry brick wall (the worst option) with prefabricated extruded polystyrene (XPS) drywall (the best option) can result in saving 1257.85 kgCO2eq. The operational phase of the studied walls has a wide range of environmental impacts. Prefabricated Knauf drywall as well as prefabricated XPS drywall consumes less energy for the operating phase mainly due to providing sufficient quantity of isolations that leads to the better total environmental performance. In conclusion, it should be noted that the thermal performance of building materials should be given more attention.

Shear performance of brick masonry walls reinforced with twisted steel bars

The present paper presents a study on the in-plane shear performance of solid clay brick masonry walls reinforced with near-surface mounted twisted steel bars. Masonry assemblages were fabricated representing those used in masonry-concrete buildings such as those found in Lisbon, built during the decades of 1930–1950. Solid clay bricks laid in Flemish bond using cement-lime blended mortar were used in the construction of fifteen wallette specimens. Three reinforcement layouts were applied on both faces of the wallettes, namely: grid (vertical + horizontal bars), vertical-only, and horizontal-only. Three unreinforced and nine reinforced specimens were subjected to diagonal compression tests. Three other unreinforced specimens were subjected to axial compression tests. The effectiveness of the proposed strengthening solution was discussed. The findings indicate that the proposed strengthening solution substantially increased the shear strength and greatly improved the ductility of the masonry wallette assemblages, pointing to its interest in practice. Although the number of tests performed is significant (considering its complexity), it should be noted that the representativeness of the results could be improved by performing more tests. The incorporation of results from other studies (in progress within the RESIST2020 research project), namely, regarding the walls out-of-plane behavior, will allow for a more complete characterization of the benefits of the reinforcement solution.

An Experimental Study of Strength Increase in Masonry Wall Reinforced by One-sided Khorasan Mortar with Steel Mesh

The strengthening of masonry structures is of paramount importance due to their inherent lack of tensile elements, rendering them susceptible to tensile stresses induced by horizontal loads and the resultant substantial damage. Consequently, this study aims to develop a reinforcement system for the strengthening of historical masonry structures by using mortars devoid of cement and modern pozzolan. Experiments were conducted on masonry walls unreinforced and reinforced by a one-sided Khorasan mortar with steel mesh. Initially, six masonry brick walls constructed using Khorasan lime mortar were prepared. Subsequently, after a waiting period of six months, Khorasan plaster mortar, reinforced with steel mesh, was applied to three masonry walls on one side. Following an 18-month waiting period, all samples were subjected to testing in an experimental setup designed and manufactured for this purpose. The wall reinforcement resulted in a significant increase, with the average peak load by 215.73%, and the average displacement by 48.82%. The experimental shear force on unreinforced walls was found to be 41.23% lower than Eurocode-6 and 1.41% lower than TBDY-2018. In the case of one-sided reinforced walls, the experimental shear force was 9.94% lower than Eurocode-6 and 6.16% lower than TBDY-2018. This form of strengthening not only obviates the use of potentially damaging cement in historical buildings but also extends the lifespan of the reinforced structures. Doi: 10.28991/CEJ-2023-09-12-019 Full Text: PDF

A Numerical Study on the Fire Induced Collapse of a Real Life Warehouse Structure Based on Post-Fire NDT Results

Fires being a Low-Probability High-Consequence problem, can have a big impact on the structures due to their occurrence; irrespective of the construction materials. Even, the damage might lead to structural collapse. Such failures have warned to check the impact of fire on structural elements, which is frequently overlooked in popular design guidelines. Warehouses are used for the storage of different types of commodities; however, the vulnerability of these structures during fire event depends on the storage materials and other factors. Such a warehouse with steel roof trusses supported over Reinforced Cement Concrete (RCC) frame, located at Kolkata, suffered one of such severe fire-induced damage; and the roof truss system along with some portions of the brick masonry walls got totally collapsed. The information about the structure including its design data is presented along with the site observations after the fire incident, and the results of various Non-Destructive Tests (NDTs) performed over RCC frame elements. A severe fire of 8-hour duration led to a huge increase in temperature, which is considered to be the main reason of the progressive collapse of the entire warehouse structure. To better understand the failure of members due to temperature load, the present study aims to analyse a numerical model of the damaged structure in the Finite Element (FE) Framework. The roof truss, RCC frames and brick masonry walls are modelled; and temperature load is applied along with self-weight load to check the effect of incremental temperature on various structural responses of the warehouse. The temperature-dependent material properties are considered in the analyses; as applicable. Results have shown that there is a significant effect of temperature load, which gets worse with increasing temperature. The connection between roof truss and columns also contributes to the extent of damage in the truss supported over RCC frames; as evident from the numerical analysis. The present study seems to present a clear view about the fire-induced structural collapse of a real-life warehouse structure

Masonry Shear Triplets Coated with Fiber Reinforced Mortars

Unreinforced brick masonry walls (URM) have been widely used in construction for centuries and represent a large part of building heritage. However, these walls are prone to cracking and failure under certain loading conditions. Addressing this issue requires a comprehensive understanding of URM structures and the implementation of effective retrofitting techniques to enhance their structural integrity. wherefore, researchers have proposed the use of thin Fiber reinforced mortar coating as a reinforcement technique. This experimental study aims to investigate the effectiveness of this approach in improving the behavior of perforated brick masonry walls. To carry out this investigation, a shear triplets test under uniaxial loading has been conducted to evaluate the performance of the reinforcement technique. A series of shear triplets were built with perforated masonry of dimensions (220 x110 × 55) using bastard mortar (1: 1: 5). These specimens were coated with a thin layer of polypropylene fiber reinforced mortar. The test results of the reinforced and unreinforced specimens were compared to analyze the effectiveness of this technique of reinforcement. The test results showed that the application of fiber reinforced coating significantly increased the deformation ability and improved the stiffness and the bond strength of the masonry walls.

Single- and double-wythe brick masonry walls subjected to four-point bending tests under different support conditions: Simply supported, rigid, non-rigid

Out-of-plane actions cause confined unreinforced masonry walls (URM) to develop what is known as an arching action. The role of arching is central in the resisting mechanisms of a wall; it contributes significantly to its loadbearing capacity as long as the wall’s deflections are minor, but gradually loses effect with increasing deflections, until collapse occurs. To date, limited experimental data is available on how arching develops in relation to the out-of-plane behaviour of the wall. This study brings new experimental evidence to this aspect. Quasi-static monotonic four-point bending tests were conducted on eleven brick wall strips, with reinforced concrete (RC) slabs affixed below and over the walls to simulate contact conditions of a typical construction system. The walls were tested vis-à-vis three different support conditions: simply supported, rigid, and non-rigid. The influence of these support conditions on the out-of-plane behaviour of the walls was studied on specimens with varying thickness – single and double wythe – and subjected to different levels of axial compression (or overload). While the former support condition was designed not to yield any arching inside the wall (unconfined masonry), the intermediate and latter solutions generated an arching action that was proportional respectively to the elongation of the wall (partially confined masonry), and its deflection (confined masonry). The walls were tested inside a bi-axial test setup that allowed not only the out-of-plane force but also the arching action to be measured, corroborating its central role in the development of the out-of-plane capacity of the walls. To support the observations, deformation characteristics and crack distributions were determined using two optical measurement systems placed in front and to the side of the walls, making use of the Digital Image Correlation (DIC) technique. The results of the tests are discussed in terms of failure mechanism as well as force and displacement capacity of the walls in relation to the investigated parameters. The test data is collected and made available to help with future research on the out-of-plane capacity of URM walls.

Effects of textile-reinforced concrete on the cyclic shear behavior of damaged confined brick masonry walls

Masonry walls are very fragile and prone to damage from the effects of earthquakes. However, after an earthquake, some of confined walls can continue to carry loads after repair and reinforcement. Strengthening is an effective measure for improving the seismic performance of damaged walls. In this study, the seismic performance of textile-reinforced concrete-strengthened damaged masonry confined walls was experimentally investigated. Apparently cracked and pre-damaged confined brick masonry walls were repaired and retrofitted with TRC (textile-reinforced concrete). The effect of anchoring on improving seismic performance was investigated, and a restoring force model of damaged confined brick masonry walls reinforced with TRC was established. The damaged masonry confined walls reinforced by TRC had better integrity and ductile behavior during the failure model, compared with unreinforced walls. Load-displacement curves of walls reinforced with TRC exhibited good postpeak behavior, and they had higher shear capacity, ductility factor, and energy dissipation. TRC surface reinforcement could provide a good restraint to damaged walls and improve the brittle failure characteristics of the walls. The number of cracks in each wall was significantly reduced, and the rate of decrease of stiffness was slowed down. For different strengthening methods, the initial stiffness, shear capacity, ductility factor, energy dissipation increased by 0.08-0.52, 0.04–0.22, 0.019–0.55, and 0.33–0.91 times, respectively, compared with unreinforced walls. Additionally, the application of anchorage measures significantly improved the shear bearing capacity and energy dissipation of the reinforced walls. Based on the experimental results, model curves of the restoring force of TRC-strengthened damaged masonry walls were given and analyzed according to the experimental results.

Evaluation of the compressive strength of autoclaved aerated concrete in existing masonry

AbstractSclerometric method, commonly used in reinforced concrete structures, have also found application in masonry structures, mainly in the diagnosis of brick masonry walls or testing mortar in joints. This article presents a proposal for determining the compressive strength of autoclaved aerated concrete masonry elements with the use of the Schmidt OS‐120 PT pendulum hammer. The test was carried out on masonry elements with a nominal density class of 400 and 600. Additional tests were also carried out on samples with different levels of humidity, in order to consider the influence of humidity on the change in rebound number and changes in compressive strength.

Numerical investigation on strengthening of brick masonry wall using mortar joint technique

Many parts of the world have used and continued to use brick masonry throughout history. Because of severe earthquakes occurring all over globe time and again, the walls face lots of damage. Hence, it is necessary to study the behavior of masonry walls and provide correct solution to strengthen it. The study is focused on providing a comprehensive review of earlier works, validation of an experimental study in a published paper using numerical analysis, ANSYS Workbench 2021 R2, wherein brick models are strengthened by providing mortar collar joint, for enhancing the load resisting capacity of the structural element. Load- deflection behavior and failure pattern illustrated explains how strength of wall improves using this technique. Also, this paper discusses how change in mechanical properties bring significant amount of change in load resisting characteristics. Cracks and deflection get minimized and load resisting capacity of masonry walls increases upto 24% (minimum).

Experimental and numerical insights on the in-plane behaviour of unreinforced and TRM/SRG retrofitted brick masonry walls by diagonal compression and shear-compression testing

The experimental determination of the parameters that characterise the in-plane shear behaviour of masonry structures is still a challenging task. Different authors have identified the key role of tensile strength in the definition of the in-plane shear behaviour of masonry, but unfortunately its direct experimental characterisation is not always feasible, and masonry’s tensile strength needs to be obtained from complex testing methodologies. As a result, tensile strength needs to be assessed from testing setups such as diagonal compression testing and shear compression testing when the failure mode of masonry is featured by tensile diagonal cracking. However, different formulations are available in the scientific literature regarding the interpretation of the experimental results derived from such tests. This work provides new insights on the interpretation of in-plane shear experimental behaviour of double-leaf historical clay brick masonry walls with low strength mortar joints, both unreinforced and retrofitted with textile reinforced mortar and steel reinforced grout. The research evaluates results derived from both testing methodologies, and investigates the potential correlation between them to fully characterise the in-plane shear behaviour of masonry walls. Finally, a numerical model is used to simulate each testing configuration and study the stress state at the centre of the walls to determine the tensile strength and its correlation with the shear strength and the maximum load attained.

Experimental study of the flexural strength of masonry brick walls strengthened with thermal insulation

The article presents the results of a testing campaign that was carried out to validate the effect of ETICS and seismic plus energy retrofitting techniques on the flexural strength of full-scale masonry brick walls. The study highlights the importance of retrofitting techniques that can improve the energy efficiency and seismic safety of existing buildings, a growing global concern. Based on this motivation, a testing campaign was carried out to validate the effect of ETICS and seismic plus energy retrofitting to improve the flexural strength of full-scale masonry brick walls. For this, nine full-scale specimens were built where three were built without retrofitting, three with ETICS and the remaining three retrofitted with a combined retrofitting technique. Each test involved applying OOP quasi-static uniform load simultaneously at the top and bottom of each wall to reach the collapse. Also, the accuracy of prediction models for non-retrofitted and retrofitted walls will be assessed. The results indicate that retrofitting techniques can significantly improve the flexural strength of masonry brick walls, with combined retrofitting techniques showing promising results for seismic strengthening. The strength and deformation capacity improved high than 200%.

In-plane shear behavior of brick masonry walls strengthened with basalt textile-reinforced concrete

The in-plane shear behavior of the brick masonry walls strengthened with basalt textile-reinforced concrete (BTRC) was mainly investigated. Diagonal shear tests with different strengthening methods and textile layers were performed. Research results show that the BTRC transforms brittle failure of the brick walls into ductile failure, the BTRC and brick wall work well together. Double-sided strengthening is more effective in reinforcing the shear capacity of the masonry walls. The strengthening effect improves with textile layers, especially for double-sided strengthening. Furthermore, the shear strength values calculated by current standard are lower than tests.

Effect of Aspect Ratio and Boundary Condition with Respect to the Bed Joint Orientation of Clay and Modified Concrete Brick Masonry Walls Against Impact Loading

Effect of Aspect Ratio and Boundary Condition with Respect to the Bed Joint Orientation of Clay and Modified Concrete Brick Masonry Walls Against Impact Loading

Shear performance of textile-reinforced concrete (TRC)-strengthened brick masonry walls

Masonry structures are a crucial component of existing building structures. Masonry walls are the main load-carrying component of masonry structures, and their failure is mainly attributed to insufficient shear capacity under extreme loading states such as during earthquakes. Strengthening is an effective measure for improving the shear performance of masonry walls. In this study, the shear performance of textile-reinforced concrete (TRC)-strengthened brick masonry walls was experimentally investigated. The TRC-strengthened brick masonry walls had better integrity and ductile behavior during the failure mode, compared with unreinforced walls. Digital image correlation (DIC) was used to characterize the failure process of the TRC-strengthened walls, and the stress transfer path was characterized. Shear stress-strain curves of the TRC-strengthened walls exhibited good post-peak behavior, and they had higher shear strength, ductility factor, and energy dissipation, compared with unreinforced walls. For different strengthening methods, compared with unreinforced walls, the shear strength, ductility factor, energy dissipation increased by 1.4–3.6, 2.6–11.5, and 10.0–54.0 times, respectively. Based on the experimental results, the shear capacity of the TRC-strengthened brick masonry walls was further calculated and analyzed according to the contemporary methods.

Quasi-static, cyclic loading tests of RAC brick masonry walls strengthened by basalt textile reinforced concrete

This study experimentally evaluated the performance of unreinforced masonry (URM) walls, with and without basalt textile reinforced concrete (BTRC) strengthening, under quasi-static in-plane lateral loading tests. Five half-scaled specimens were constructed using recycled aggregate concrete (RAC) bricks, including unreinforced and BTRC reinforced walls. The first URM wall served as a control specimen, while the remaining four specimens featured varying strengthening configurations, achieved by changing the number of textile layers (two and four) in the BTRC overlay and the strengthening patterns (single and double side). The failure modes, axial deformation behavior, lateral resistance, deformability, stiffness degradation, energy dissipation, and equivalent viscous damping of the tested walls were examined. BTRC strengthening altered the failure mode of URM walls from diagonal cracking accompanied by rocking to rocking and slight shear sliding, thereby maintaining the integrity of the wall at large lateral displacements. Increasing the textile layer enhanced lateral resistance and deformability. Applying a BTRC overlay to a single side of the URM wall yielded satisfactory improvements, with even greater efficiency observed when an equal amount of textiles was evenly applied on both sides. Finally, by taking the contributions of vertical and horizontal fiber yarns into account, a new model involving different failure modes was proposed to estimate the ultimate lateral resistance of BTRC-strengthened masonry walls, showing good agreement with experimental results.

Structural and fire performance of masonry walls with ceramic bricks

Ceramic brick masonry construction systems have long been used in civil construction. Understanding their performance at high temperatures is important, as several fires have occurred in recent years in these types of buildings. Therefore, in this study, the structural performances of 16 ceramic brick masonry walls under typical service and fire loads were experimentally analyzed. Parameters, such as the type of ceramic bricks (non-structural common and structural with horizontal and vertical perforations, respectively), the type of test (at room temperature and fire resistance test), load level, and laying mortar were tested. Walls with structural ceramic bricks exhibited low resistance capacities under ambient conditions, which were below normative values and close to practical service load levels. In the event of a fire, the walls constructed with common brick exhibited low fire resistance (FR), not reaching the 30-min class. Structural ceramic brick walls exhibited better fire performance, reaching the 150-min class, but higher loads considerably reduced this time.

To Investigate Different Parameters of Economic Sliding Based Seismic Isolation System

ABSTRACT Masonry structures are frequently constructed in developing countries because of their affordability and ease of construction, even though they are vulnerable and perform poorly during earthquakes. Experimental and numerical studies were carried out to determine the optimum thickness of the isolation layer for a recently developed, low-cost seismic isolation system known as the Reinforced-Cut-Wall (RCW). The parameters of the isolation layer were optimized during the experimental and numerical investigations using hollow concrete blocks. Quasi-static cyclic tests were performed on a 1:3 reduced-scale brick masonry wall incorporating the RCW isolation scheme, validating the better performance of the proposed isolation technique.