Masonry Walls Research Articles

A Digital Image Correlation Technique for Laboratory Structural Tests and Applications: A Systematic Literature Review

Digital image correlation (DIC) is an optical technique used to measure surface displacements and strains in materials and structures. This technique has demonstrated significant utility in structural examination and monitoring. This manuscript offers a comprehensive review of the contemporary research and applications that have leveraged the DIC technique in laboratory-based structural tests. The reviewed works encompass a broad spectrum of structural components, such as concrete beams, columns, pillars, masonry walls, infills, composite materials, structural joints, steel beams, slabs, and other structural elements. These investigations have underscored the efficacy of DIC as a metrological instrument for the precise quantification of surface deformation and strain in these structural components. Moreover, the constraints of the DIC technique have been highlighted, especially in scenarios involving extensive or complex test configurations. Notwithstanding these constraints, the effectiveness of the DIC methodology has been validated as a strain measurement instrument, offering numerous benefits such as non-invasive operation, full-field measurement capability, high precision, real-time surveillance, and compatibility with integration into other measurement instruments and methodologies.

Mutual Effect Between Moisture Transfer and Mechanical Response in Infill Masonry Walls of Reinforced Concrete Building Envelope

The external envelope of buildings with reinforced concrete structures (RCS buildings) is subjected to environmental actions, particularly related to wind-driven rain (WDR), external humidity variations, and rising dampness, which can cause significant variations in moisture content to their unreinforced masonry (URM) infill walls, mainly associated to water penetration across that envelope. The consequent moisture transfer across the envelope can change the mechanical response of the URM infill walls and lead to their cracking, which could aggravate the referred water penetration, with a subsequent increase in the risk of building envelope degradation. In reverse, the effects of mechanical loads on moisture transfer across that envelope can be also relevant, in terms of change in the moisture content of these URM infill walls. The aim here is to analyze this type of mutual effect between moisture transfer and mechanical response in URM infill walls of RCS buildings. Essential elements about the characteristics of moisture transfer across URM infill walls and of the interface resistance with moisture flows are summarily described, and the essential evaluation of the mechanical behavior of URM infill walls when subjected to moisture variations is carried out. Moisture transport characteristics are discussed, focusing on analyses of the behavior of masonry elements when subjected to moisture variations. An initial assessment of the mechanical behavior of URM infill walls when subjected to different moisture variations is made through a compression test of a brick masonry specimen with variable moisture content. Following that analysis, an evaluation is made of the moisture transfer in URM infills, as well as the influence of the interface between layers in that moisture transfer and, subsequently, an assessment is made of hygromechanical couplings. Finally, elements for prevention about the causes of degradation of URM infill related to humidity and mechanical actions in the RCS building envelope are discussed.

A Damage Index for Assessing Seismic-Resistant Designs of Masonry Wall Buildings Reinforced with X-Bracing Concrete Frames

In this paper, a suitable damage index is demonstrated to assess the seismic-resistant design of masonry wall buildings reinforced with double x-bracing concrete frames. As a criterion indicative of the damage level that might occur after an earthquake, the damage index can be calculated by using analytic results, by using the Park–Ang formula on masonry wall buildings reinforced with concrete structures, and by adjusting the index values in accordance with the results of the analysed models. The data used in this study are collected from the results of four-storey concrete structures with masonry walls under cyclical lateral forces. To simulate the masonry walls’ structural behaviours for damage assessment, x-bracings placed as crosses on each bracing are used to support the compressive strength. Then, the analysis results are used to assess the damage that occurs to the masonry wall building structure by considering deformation and energy decay; additionally, a suitable damage index is calculated for each damage level. The damage index can be considered in the seismic-resistant design of masonry walls reinforced with x-bracing concrete frames.

Comparative numerical study to simulate masonry with bed joint reinforced repointing

Bed joint reinforced repointing is a retrofitting technique for unreinforced masonry structures that is commonly applied in the Netherlands to repair settlement-induced damage. Using this technique, the bed joints of masonry walls are reinforced with steel rebars that are embedded in a high strength repair mortar. Due to the increase of induced seismic events in the northern part of the Netherlands, an experimental study was carried out at Delft University of Technology to investigate the performance of this retrofitting technique for combined settlement and seismic loading. This paper aims to simulate the experimental results, with a focus on the comparison of different finite element modelling approaches for studying both un-strengthened and strengthened full-scale tested walls. To that end, three different models are investigated – comprising both macro (continuum) and simplified and detailed micro (brick-to-brick) modelling approaches. The bricks and mortar joints are modelled as one homogenous continuum in the macro model, whereas in the two brick-to-brick models these structural components are modelled separately, with the detailed model including interface elements to simulate the brick–mortar bonds. Nonlinear pushover analyses are subsequently carried out using all three modelling approaches, for both monotonic and cyclic loading cases. Based on these analyses, the detailed brick-to-brick model was found unsuitable to simulate the strengthened wall because cracks in the model mainly occur in the form of opening of the brick–mortar bond interfaces, while smeared cracking in the plane stress elements of the mortar joints is very limited. Similarly, the continuum damage model was found to be inaccurate when pre-existing damage in the experiment needed to be taken into account. The continuum damage model also showed lower axial stresses in the rebars, compared with the simplified brick-to-brick model, as the former does not allow for the direct assignment of material properties for the high strength repair mortar in the strengthened joints.

IMPACT RESISTANCE ASSESSMENT OF INTERLOCKING COMPRESSED EARTH BRICKS (ICEB) INCORPORATING CRUMB RUBBER

Interlocking compressed earth bricks (ICEB) are a cleaner and sustainable alternative to conventional fired bricks and it has comparable strength to other masonry systems, making it feasible for both cladding and load-bearing purposes. However, it tends to be brittle and has poor performance under impact loading. Impact resistance of masonry walls are important as one of the main purposes of cladding is to protect its occupants from external projectiles. This study was commissioned to investigate the feasibility incorporating both crumb rubber (CR) and treated CR into ICEBs in place of sand to improve its impact resistance. The drop weight impact tests carried out concluded that ICEBs containing CR have better impact resistance and this was further improved with heat-treated CR. Heat-treated CR ICEBs also had less catastrophic failure compared to untreated CRs which had pieces of materials spalling off. Mechanical tests also show that this improvement in impact resistance comes at the expense of a minor loss in compressive and flexural strength at replacement levels higher than 7.5 %. Heat-treated CRs also showed higher losses of mechanical strength compared to untreated CRs.

In-plane seismic behaviour of urm and confined masonry built from vertically perforated blocks and polyurethane glue

Masonry construction using vertically perforated clay blocks with large holes and polyurethane glue is a modern technology designed primarily for low thermal losses. This study aims to evaluate the in-plane seismic behaviour of masonry constructed using unreinforced masonry (URM) and confined masonry construction technology. The experimental methods consist of triplet tests on joints and cyclic shear compression tests on eight full-scale walls, six of which are URM and two of which are confined masonry. Tests on URM walls are performed at three different levels of compressive stress to analyse the effect of compressive stress on the seismic response. The effects of compressive stress on shear resistance and drift capacity are quantified and compared with results from a database. The performance of the tested walls is comparable to what is expected from modern URM walls. Two confined masonry walls were of the same dimensions as the URM walls and are evaluated at the highest compressive stress level used in tests of URM walls. The results indicate that confined masonry should be the preferred technology for seismic regions because of its higher strength, displacement capacity, ductility, and energy dissipation.

Performance of partially grouted reinforced masonry walls with bed-joint reinforcement: parametric and optimization investigation

Performance of partially grouted reinforced masonry walls with bed-joint reinforcement: parametric and optimization investigation

Performance of Unreinforced Masonry Walls in Compression: A Review of Design Provisions, Experimental Research, and Future Needs

Unreinforced masonry (URM) is a construction of brick or concrete block unit that is joined together using mortar, without steel reinforcement. Because of the heterogeneous nature and difference in mechanical properties of the masonry elements, analyzing and capturing the structural behaviour of URM walls under various loading conditions is therefore complex. In recent decades, research efforts have been focused on addressing and understanding the compressive behaviour of URM walls from the experimental viewpoint. However, from the existing experimental literature, there is a significant degree of variation in the mechanical and geometric properties of URM walls, especially the comprehensive comparison of apparently equivalent test parameters, which has yet to be examined. It is therefore necessary to highlight and critically examine major results derived from the experimental literature to better understand the performance of URM walls under compressive loads. This review paper presents the assessment performance with regard to axial compressive tests on URM walls, along with comprehensive comparisons among the experimental literature findings on the basis of masonry construction methods and various influencing parameters. Emphasis in the literature has been placed chiefly on the masonry elements, design provisions, axial load, slenderness ratio, openings, and stress–strain response. Based on observations from the study, experimental development trends have been highlighted to identify and outline potential directions for future studies.

Impact of Uninsulated Slab-on-Grade and Masonry Walls on Residential Building Overheating

Studies of the effects of removing underfloor insulation and increasing the thermal capacity of building walls are currently found almost exclusively in existing vernacular architecture and rammed-earth buildings, mostly in countries with warm climates. This paper proposes the combined use of these two measures to reduce the risk of overheating in a detached single-family house in a temperate climate during the summer. Experimental studies conducted during the largest heat wave on record in the summer of 2019 showed that peak daytime temperatures decreased by 5.2 °C to 7.1 °C, and peak nighttime temperatures decreased by 4.7 °C to 6.8 °C. Simulation studies taking into account occupant heat showed that the proposed passive methods could, under the IPCC 8.5 scenario, eliminate the need for mechanical cooling in a detached single-family house in the temperate climate of Central and Eastern Europe by 2100. The actual heating energy consumption for the building with an uninsulated floor and increased wall heat capacity was 5.5 kWh/m2 higher than for the reference building, indicating that it can be a near-zero energy building. The proposed concept is in line with the new approach to the energy design of buildings, which should not be limited to reducing thermal energy demand, but should also respond to the needs arising from global warming.

Low-carbon design optimization of reinforced concrete building structures using genetic algorithm

ABSTRACT Embodied carbon emissions are getting increased attention to realize low-carbon buildings. Low-carbon designs have been explored by conducting both member-level and structure-level analyses for concrete structures. However, methods for combining two-tiered research need to be further developed to reduce the cost of design optimization. This study aims to propose a hybrid iterative approach for the low-carbon optimization of concrete framed structures. Accordingly, the integrated structural analysis was applied to design the initial scheme, subproject-based emission assessment was applied to identify the carbon-intensive structural components, and a genetic algorithm was applied to optimize the desired components subjected to relevant design constraints. A case study was made on a residential building to verify the feasibility of the proposed approach. The optimization results indicated that a potential 18.3% and 4.2% reduction in the embodied emissions from the beams and the building main body were achieved, respectively. A further discussion also proposed that an optimized scheme for interior walls using lightweight panels resulted in a 12% reduction in carbon emissions compared to the initial scheme using masonry walls. The proposed method and results can facilitate understanding the low-carbon design optimization of reinforced concrete structures and, therefore, contribute to carbon reduction of the construction industry.

Cyclic behavior of masonry walls retrofitted with post-installed twisted bars or bonded rebars

The damage observed after the recent earthquakes showed that the most common failures for masonry buildings involve out-of-plane mechanisms associated to the ineffective connection between walls. For this reason, retrofitting techniques aiming to achieve a box-like behavior are of great interest. This paper presents the results of an experimental study conducted to investigate two different retrofitting solutions used to improve the structural connection between orthogonal walls: a mechanical connection by means of twisted bars and a fastening solution with rebars and injection mortar. Two full-scale T-shaped masonry specimens were realized in solid clay brick, with a “weak” connection between the front and the back wall. The specimens were tested in unreinforced and strengthened configurations, considering different retrofitting layouts. An out-of-plane load was applied on the front wall, together with a vertical prestress to simulate the gravity load coming from the floors and walls above. Each specimen was tested in three consecutive runs: a monotonic one on the unreinforced masonry, a first cyclic run with the wall intersection reinforced with twisted bars, and a second cyclic run on the wall retrofitted with rebars and injection mortar, after the removal of the twisted bars. The twisted bar solution resulted in a significant increase of the dissipative capacity of the wall despite the number of adopted bars, while, in the case of rebars and adhesive, a higher resistance was achieved together with a perfect box-like behavior.

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

Stability of the ‘Tensyudai’ of a Japanese castle under a long-term load

‘Tensyudai’ is the term used for the truncated masonry base that supports the main tower (Tensyukaku) of a Japanese castle. In response to concerns regarding the structural integrity and conservation of Tensyudai masonry walls, this study seeks to investigate the mechanism of their collapse and load capacity. A reduced-scale model of Tensyudai, based on Osaka Castle, was constructed and subjected to a vertical load test to evaluate its three-dimensional mechanical properties. This paper postulates a collapse mechanism, and the equilibrium of forces for the Sumiishi and Hiraishi sections of the Tensyudai is analysed, considering the arch effect. Experimental results are compared, using a series of equations to calculate the collapse burden (q c). Additionally, the safety factor is determined, based on the active earth pressures at various masses. The findings indicate that the safety factor of a standard Tensyukaku weight is approximately 25, which rises with increased Tensyukaku weight. Moreover, this study contributes to future research and preservation efforts for historical structures, by shedding light on the structural stability and safety of Tensyudai masonry walls. It can also provide basic data for considering the protection of other masonry wall structures from earthquakes.

Development of Backbone Curve for Reinforced Concrete Frames with Confined Masonry Walls

Development of Backbone Curve for Reinforced Concrete Frames with Confined Masonry Walls

Enhancement of in-plane shear performance in masonry walls strengthened with high-performance fiber-reinforced cementitious composites

This study aims to design a high-performance fiber-reinforced cementitious composite (HPFRCC) material for reinforcing masonry walls and assess its impact on in-plane shear performance. Different specimens were compared, including an unreinforced one, a conventional mortar-reinforced one, and HPFRCC-reinforced specimens of varying thicknesses ranging from 10 mm to 20 mm. Aspects such as failure modes, shear stress–strain curves, pseudo-ductility, and energy dissipation were evaluated. Test results indicated that the unreinforced and mortar-reinforced masonry walls demonstrated brittle failure with wide cracks on both sides, whereas HPFRCC-reinforced walls exhibited ductile failure with controlled crack propagation owing to the excellent mechanical properties of HPFRCC, such as an average tensile strength of 7.32 MPa and a tensile strain capacity of 4.60 %. The HPFRCC significantly enhanced the shear strength and modulus of the masonry walls. The wall reinforced with 20 mm-thick HPFRCC showed a remarkable 26-fold increase in the energy dissipation capacity compared to the unreinforced one, and the 10-mm-thick and 15 mm-thick strengthening demonstrated 4.0- and 5.7-times improvement, respectively. The ideal HPFRCC overlay thickness was found to be between 15 mm and 20 mm. Beyond this thickness, gravitational flow and stiffness asymmetry negatively impacted shear performance.

Out-of-plane performance of structurally and energy retrofitted masonry walls: geopolymer versus cement-based textile-reinforced mortar combined with thermal insulation.

This paper examines the out-of-plane performance of masonry walls (representative of infills in reinforced concrete frames) which have been upgraded with an outer skin of integrated structural and an energy retrofitting system. The benefits of such an integrated system are mainly cost-related. Nevertheless, before moving to full-scale applications, additional benefits to the structural performance need to be investigated. In this study, the examined configurations of this composite system comprised either thermal insulation boards bonded directly to the wall followed by layers of textile-reinforced mortar (TRM), or thermal insulation boards bonded in-between two TRM layers. Other than the retrofitting layers configuration, the following parameters were also investigated: a) the binder type (cement-based versus geopolymer-based mortars), and b) the textile type (open mesh glass fibre textile versus basalt fibre textile). The results of this experimental study are discussed in terms of failure modes, post-cracking stiffness and ultimate capacities. Overall, this study highlights the mechanical benefits of the TRM plus thermal insulation system while providing insights on the bond performance between the different materials selected. An important finding is that the integrated system is even more effective than a standard TRM application. Finally, the geopolymer mortar seems to be equivalent in terms of performance to the commercially available cement-based mortars.

Behavior of grout injected solid stone masonry walls under in-plane loading

It is a shared duty of all humanity to ensure the preservation of historical structures for future generations. The discontinuities, cracks, and gaps in the masonry walls, especially in historical structures, prevent the building from working monolithically. For this reason, historical buildings need repair and strengthening efforts in time. Grouting is an effective technique for consolidating and strengthening masonry structures. This study aims to establish a general evaluation of the injection method used to repair damaged stone walls. For this purpose, solid stone masonry walls were constructed and tested under in-plane loading to simulate the actual conditions. The solid stone masonry walls are made of saw-cut travertine stones and plastered with English bond, a pattern formed by laying alternate courses of stretchers and headers. The mechanical behavior of the solid stone masonry walls, both in non-damaged condition and with grout injected into the cracks caused by the preloading, was monitored and demonstrated in terms of the load-displacement relationship. As a result of the wall tests, it was observed that there was an increase of up to 28% in the maximum lateral load that the walls can withstand without any crack formation after grout injection.

Out of-plane failure analysis of masonry walls subjected to hydrostatic and hydrodynamic loads induced by flash floods

Damage surveys from past flash flood events show that the combined hydrodynamic impulsive loading and the subsequent hydrostatic loading due to rising water levels caused the failure of masonry walls/buildings. However, limited studies have been conducted to understand the responses of masonry walls to these loading states. To bridge this knowledge gap, an explicit 3D shell element based finite element modelling method that incorporates a homogenised anisotropic masonry material model was developed and applied to analyse the out-of-plane collapse behaviour of masonry walls under flash flooding conditions. The developed modelling method was validated with an available experimental study of masonry wall subjected to hydrostatic loading conditions. It was then extended to comprehend the behaviour of masonry walls under hydrodynamic impulsive water pressures. Results reveal that the effect of hydrodynamic impulsive loading generated by the first hit of the flash flood water is significant in reducing the stiffness of the masonry. This reduction in stiffness can result in an early collapse of the wall, even with a gradual rise of hydrostatic water level. This study has also evaluated the behaviour and damage patterns of masonry walls with two different slenderness ratios (single brick/24.5 and double brick/11.7) under flash flooding and prescribed the maximum percentage of surface area of inundation that the walls can resist. The importance of considering hydrodynamic impulsive loading in designing masonry buildings vulnerable to flash flooding and the capability of the modelling technique developed in this research for evaluating their vulnerability under these flooding scenarios are highlighted.

Review on Masonry Hollow Block Walls: Materials and Construction

Concrete hollow blocks are commonly used in building construction, particularly for multi-story buildings, factories, and residential structures. Hollow blocks are more practical because of their lightweight, and the most significant feature is the ease with which they can be ventilated. This paper provides an overview of modern masonry hollow block wall construction, starting with an overview of its applications and benefits. Mortars are typically made from cement and sand; with lime or a plasticizer added to improve workability. To improve economy and productivity, compressive strength, density, masonry hollow block properties, and masonry wall behaviour with the factors to consider for load-bearing and non-load-bearing wall construction were summarised and described, and key reference lists are included.

Lateral behaviour of unreinforced masonry walls with different sizes and locations of opening and effect of strengthening measures: a computational approach

Lateral behaviour of unreinforced masonry walls with different sizes and locations of opening and effect of strengthening measures: a computational approach