Clay Brick Walls Research Articles

Damage assessment method of clay brick masonry load-bearing walls under intense explosions with long duration

The vulnerability of clay brick masonry load-bearing (CBML) walls under low-intensity explosions has been extensively investigated. In recent years, large-scale explosions have raised wide concerns about the destructive effect of intense explosions. Intense explosions induced by large TNT equivalent explosives usually cause severe damage to building structures within several kilometers. Although the damage of building structures under intense explosions and normal low-intensity explosions might be different, the differences have yet received any attention in previous studies. Therefore, this study numerically investigates the dynamic performance of CBML walls under intense explosions with long duration (IELD). Firstly, the numerical model is validated by reproducing experimental records. Then the verified model is utilized to investigate the dynamic response and dynamic modes of CBML walls under IELD. Based on the identified failure mechanism, the effects of several parameters such as axial compression ratio, compressive strengths of masonry materials and wall geometry on the damage degrees of CBML walls are analyzed in detail. The damage index based on the residual axial loading capacity of CBML wall is proposed for damage evaluation. The damage assessment method is established for CBML walls under IELD, which can help to evaluate the damage level of clay brick masonry structures under far-field intense explosive scenarios.

Mechanical performance of coal ash based interlocking bricks wall panel: A sustainable and viable solution

The use of interlocking brick incorporating waste coal ash (CA) in masonry construction is an innovative, sustainable and viable solution to address the consequences associated with burnt clay bricks. In this research, the main focus was to study the double interlocking brick incorporating CA for its potential use in masonry construction. The studied dosages of CA were 30 %, 35 %, 40 %, 45 %, 50 % and 55 %. Cement was varied between 5 % and 30 % in order to make the total binder (cement and CA) contents equal to 60 %. Moreover, wall panels using developed interlocking bricks were casted and tested for out-of-plane loading. It was observed that the incorporation of higher dosage of CA decreased the compressive strength owing to porous nature of used CA. However, interlocking bricks having 30 % of CA exhibited compressive strength higher than 8 MPa, satisfying the local building code requirement. Higher water absorption was observed for interlocking bricks having higher dosage of CA compared to identical bricks with lower CA. Interlocking bricks exhibited higher shear strength due to mechanical anchorage provided by the keys and notches in comparison with the conventional bricks. Maximum double key shear strength of 2.34 MPa was observed for developed interlock bricks incorporating 30 % of CA. Interlocking brick wall panel exhibited flexural strength of 1.05 MPa compared to 0.81 MPa for wall panel constructed using conventional burnt clay brick. Higher flexural strength of interlock CA based brick wall panel was due to the higher mechanical anchorage provided by the projected keys and grooves in between various courses of the wall panel. The cracking patterns of interlocking brick wall panel exhibited diagonal failure rather than the horizontal slide shear failure observed for conventional burnt clay brick wall panel. The experimental cracking load values were comparable with the theoretically predicted cracking loads for the tested wall panels. This study highlights the use of water cured interlocking brick incorporating waste CA for eco-friendly and economical construction leading to avoid the devasting effects of manufacturing process of conventional burnt clay bricks and deposition issues of CA. Moreover, this study motivates the construction stakeholders to employ double interlocking bricks of similar conventional size bricks to be used in a similar manner for masonry construction.

An integrated life cycle assessment and energy simulation framework for residential building walling systems

Designing building wall systems is a multi-criteria problem characterised by a complex interplay of variables that drive long-term energy and environmental performance. Achieving holistic sustainability outcomes will require the application of life cycle thinking to the design and evaluation of building walling systems. However, the aspiration for minimising operational and embodied energy and mitigating the environmental impacts requires conflicting strategies. Therefore, this study proposes a comprehensive, integrated life cycle and energy simulation (ILES) methodology for analysing different walling systems of residential buildings in India and Australia. This method involves performing a process-based life cycle assessment to compute the environmental impacts of various walling materials, followed by energy modelling to evaluate the performance of these materials in the operational phase of buildings in combination with embodied energy analysis, which accounts for energy consumption during the material manufacturing phases. The results reveal that insulated cavity-clay masonry or concrete walls with extruded polystyrene are favourable Australian walling options, while metal cladding-based walling systems have significant environmental and energy burdens. For India, autoclave aerated block, fly ash bricks, and concrete block-based walling systems are recommended, while reinforced concrete and clay brick walls exhibit significant environmental and energy burdens. This study also advocates the consideration of supply chains in mitigating Scope 3 emissions from building walling systems in residential buildings.

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.

Design method for masonry structures retrofitted with steel reinforced plaster

In this paper an analytical approach for the design and assessment of masonry structures retrofitted with steel reinforced plaster (SRP) is proposed. The aim of the proposed method is to consider the main parameters affecting the performance of the strengthened wall (such as masonry properties, plaster properties, spacing and number of connectors) and provide a general formulation for practitioners to use in the design of SRP retrofitting interventions in place of the common empirically-based numerical coefficients proposed by the Italian Standard. The approach is developed starting from the experimental results of diagonal compression tests performed on clay brick walls retrofitted with SRP presented by the authors in previous studies. The maximum load is analytically predicted considering that the plaster and masonry layers work in parallel. A validation is conducted using additional experimental data available in literature. The obtained formulation is able to approximate the experimental values, being on the safe side against them in most of the cases. It is important to note that the method has been developed and validated using a limited number of experimental results. For this reason, adjustments may be needed for different types of masonry, plaster or anchor configurations.

Shear damage repair of masonry walls using different materials

In this research, the effects of different repairing materials and techniques used on damaged Masonry walls under an in-plane lateral loading were investigated. Seven clay brick walls with dimensions of (1200 × 935 × 115) mm were tested. The walls were tested until a visible crack was observed, later repaired, and tested again up to failure. The repairing materials consisted of grid configured strip materials (metal, plastic, flat webbing ‘textile’ and wild cane ‘organic’ strips), near surface mounted (NSM) steel re-bars and steel wires in mortar joints. Based on the experimental results, the repairing materials/techniques restored the shear strength by about 48–103% of the original strength. The ductility factor of the repaired walls ranged from 4.5 to 48.3 (flat webbing ‘textile’ highest). The energy dissipation ratio of the repaired walls ranged from 4.3 to 12.7 (flat webbing ‘textile’ highest). Prediction equations for shear strength are presented giving reasonable results compared to the experimental results.

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.

Thermal Performance Study of Building Materials in an Urban Form

A tropical Chennai city, is already enduring heat stresses in its urban areas and is extremely vulnerable to temperature rise. Furthermore, Chennai continues to expand, thus the need to conduct research and make informed decisions on sensible strategies and regulations on how to construct and with what to construct attains much significance in recent times. One of the major contributors to the urban heat is the materials used on the surfaces of the urban form. The current paper assesses and demonstrates the performance of two wall materials – Clay Brick and AAC, usually utilized in urban developments within the context of an optimal urban morphological region. This is accomplished by making a compact mid-rise urban form of residential typology and utilizing ENVI-met 4.0 and re-creating the outdoor microclimatic conditions with AAC and Clay Brick walls. The urban form created with the Clay brick walls are found to be cooler by 0.010°C. Compared to daytime, at night time, the outside air temperature with clay brick walls and AAC dividers are cooler respectively. This investigation additionally discovered that a huge distinction to outside air temperature for studied urban form structure can be made by expanding the Sky View Factor (SVF), contrasted with an adjustment of material. The understandings from this study can be expanded and be applied productively to impact changes in Urban development guidelines.

Strengthening of clay brick masonry wall with spraying polyurea for repeated blast resistance

As one of the main components of a building, the collapse of masonry walls under blast load and the ejection of debris were essential factors that caused injured and damage to internal personnel and facilities. In terrorist bombing attacks, masonry walls will likely undergo multiple blast loads. It is a significant problem to develop new protection technology to enhance the resistance of masonry walls to multiple blast loads. In this study, the anti-blast protection technology of spraying polyurea is proposed, and a numerical model was developed to accurately predict the dynamic response and damage behavior of unreinforced masonry wall (UMW) and polyurea reinforced walls (PRWs) under repeated blast loads. A detailed micro modeling approach was used to establish a numerical model, and the accuracy was verified by the field test results. The failure mechanism and protection mechanism of the polyurea under repeated blast loads were clarified with microscopic detection technology. Finally, through parametric analysis, the damage behavior of PRW under close-in extreme repeated blast loads was studied. According to the calculation results of the numerical model, the damage level diagrams under different scaled distances were established. The results showed that when the scaled distance was no less than 0.25 m/kg1/3, the existence of the polyurea coatings could provide reliable protection for the wall without catastrophic damage. The contribution is to provide a reliable numerical prediction tool and a reference guide for engineering design that can predict the dynamic response of PRW under repeated blast load, and to provide a scientific basis for the practical application of polyurea in building anti-blast.

Experimental quasi-static out-of-plane test of a U-shaped brick masonry wall

Past earthquakes demonstrated the vulnerability of brick masonry façade walls even against moderate earthquakes. The present work aims at providing an insight into the out-of-plane response of clay brick masonry walls, especially focusing on a traditional Portuguese building typology, namely the ‘placa’, towards a correct interpretation and assessment of their seismic behaviour. A thorough experimental campaign in laboratory environment was conducted, including material characterisation through destructive and non-destructive techniques and the quasi-static test with airbag on a U-shaped clay brick masonry specimen. Main experimental results are discussed with specific attention to the analysis of the masonry wall cyclic response, the damage pattern, the seismic performance, and the evolution of the modal parameters at distinct stages of the test. The material characterisation demonstrates the low mechanical properties of the masonry associated with such buildings. The specimen presents a stiff and almost linear behaviour until the peak, followed by an initial softening until about 60% of the peak. The damage pattern evidences a failure governed by an out-of-plane rotation combined with shear sliding.

Exploring the Cooling Potential of Ventilated Mask Walls in Neo-Vernacular Architecture: A Case Study of André Ravéreau’s Dwellings in M’zab Valley, Algeria

This study investigates the thermal performance of the ventilated mask wall used in the low-income neo-vernacular dwellings designed by André Ravéreau to cope with the warm desert climate conditions of M’zab Valley, Ghardaia, in southern Algeria. This device is a ventilated façade provided with an opaque external massive cladding. It is designed to be particularly efficient in hot climates, functioning simultaneously as a brise-soleil and a ventilated façade, compared with conventional façade systems. Based on a typical experiment conducted during the summertime (12–14 August), a residential unit in Sidi Abbaz selected as a case study was modeled and calibrated using EnergyPlus (v8.4) software, and then a dynamic simulation was performed in order to assess the efficiency of the ventilated mask wall as a cooling strategy. By means of the validated thermal model, various alternatives for the façade materials were investigated, and the thermal behavior of the current ventilated mask wall was compared with a 45 cm thick limestone façade wall, and a 30 cm thick hollow clay brick wall under the same conditions. Countless benefits were achieved by the application of the mask wall system, including a stable and less fluctuant inner surface temperature, and a reduction in the incoming summer heat flux. The improvements performed, in particular the time lag of 12 h and the related decrement factor of 0.28 indicate the effectiveness of this wall system, which enabled radiant temperature drops of more than 10 °C, and an air temperature decrease of about 6 °C, during the summer sunniest hours. The results demonstrate that this solution is suitable for buildings design applications to meet the objective of low-energy demand in warm desert climates.

Seismic Retrofitting of Mid-Rise Unreinforced Masonry Residential Buildings after the 2010 Kraljevo, Serbia Earthquake: A Case Study

There is a significant building stock of post-WWII low- and mid-rise unreinforced masonry (URM) buildings in Serbia and the region (former Yugoslavia). Numerous buildings of this typology collapsed due to the devastating 1963 Skopje, Yugoslavia earthquake, causing fatalities, injuries, and property losses, as well as experienced damage in a few recent earthquakes in the region, including the 2010 Kraljevo, Serbia earthquake (MW 5.5) and the 2020 Petrinja, Croatia earthquake (M 6.4). These buildings are three- to five-stories high, have clay brick masonry walls, and rigid floor slabs, usually with an RC ring beam at each floor level. This paper presents a case study of a URM building which was damaged due to the 2010 Kraljevo earthquake and subsequently retrofitted. A comparison of seismic analysis results, including the capacity/demand ratio and displacement/drift values, for the original and retrofitted building according to the seismic design and retrofit codes which were followed in Serbia as well as some of the neighboring countries for several decades and Eurocode 8 has been presented. The results of this study show that the selected retrofit solution that satisfied the Yugoslav seismic code requirements is not adequate according to the Eurocode 8, primarily due to significantly higher seismic demand.

Experimental study on the seismic performance of clay brick masonry wall strengthened with stainless steel strips

Strengthening the existing masonry structures with stainless steel strips is a new strengthening approach, which combines the advantages of compatible-to-masonry, chemically stable, durable, effective retrofitting, and low impact on the existing masonry structure. The horizontal and vertical stainless strips was anchored into the masonry wall with the angle steel and steel pipe to improve its in-plane tensile strength and ductility. To study the seismic performance of brick masonry walls strengthened with stainless steel strips, one masonry wall and five stainless steel strip strengthened masonry wall specimens with different packing modes and grid spacings were tested under low frequency cyclic loading. The experimental results show that the proposed strengthening approach can efficiently improve the seismic performance of the existing masonry structures, such as the load bearing capacity, ductility, stiffness, and energy dissipation capacity. The failure modes and damage evolution law of all the specimens were compared and analyzed. The load bearing capacity and hysteretic curves of the specimen were calculated using the proposed calculation formula and restoring force model, respectively. The calculated results are consistent with the test results, which provides an appropriate theoretical support and design basis for the masonry reinforcement design with stainless steel strips.

Transient dynamic response of brick masonry walls under low velocity repeated impact load

An experimental and numerical investigation have been carried out on the clay brick masonry walls against repeated impact load in order to estimate the transient dynamic response. The experiments were carried out on 110 mm thick masonry walls against 60 kg mass impactor with hemisphere nose shape with the velocity of 1.98 m/s. In the first phase, the experiment on the wall of 1.2 × 1.2 m (height (h) x breadth (b)) was conducted considering the bed (W1) and head (W2) joint of walls parallel to the boundary in order to verify the conservative design of the joint interface. It was observed that the W2 found resistance up to 3 hits whereas W1 offered resistance up to 11 hits and it was concluded that the W2 found to be sensitive. In the second phase, the aspect ratio of sensitive wall W2 was varied by reducing the breadth from 1.2 to 0.25 m, corresponding aspect ratio (h/b), 1.33 – 4.8 (W3-W6) whereas, the height of the wall remains constant, i.e. 1.2 m. It was observed that the aspect ratio was found to have marginal effect on the peak force however it changes the failure pattern significantly. In the third phase, the influence of mortar strength has been studied and it was observed that the mortar strength does not impart any stiffness into the wall. As a fourth phase, the response of W2, W3 and W4 walls was studied under repeated loading and the resistance offered up to 2, 3 and 2 hits by W2, W3 and W4 walls, respectively. Further, numerical simulations on W1, W2, W3 and W4 walls were carried out using ABAQUS and the Drucker Prager model and traction separation law were used to simulate the brick and interface joints, respectively. The results thus predicted were compared with the experimental results and found in good agreement however, a maximum deviation of 14% on the prediction of peak force. Further, the sensitive parameters were identified which are sensitive to the qualitative numerical results. It was concluded that the parameters such as cohesion, fracture energy, friction and penalty stiffness found to affect the numerical results significantly. Further, wall W2 with externally bonded engineered cementitious composite (ECC) layers has been studied in order to estimate the resistance of wall with backing plate. It was concluded that the ECC backing plate was found to enhance the response of masonry wall in terms of contact force, damage and failure pattern, significantly.

A study on the detection of bulging disease in ancient city walls based on fitted initial outer planes from 3D point cloud data

Bulging is a common disease suffered by ancient city walls, especially clay brick walls. Bulging affects or even threatens the stability of outer structures of ancient city walls. Therefore, accurate identification of bulges is one of the urgent issues to be addressed in ancient city wall conservation. In this study, a novel method is proposed for detecting and identifying bulge information using point cloud data collected from the outer surface of an ancient city wall. The non-bulging points are identified in the sliced point cloud of a city wall, and then the initial plane of the city wall is fitted more accurately with the aid of spatial constraints. Finally, the bulging damage is identified and extracted by comparing the initial plane with the original point cloud. This method was applied to the project of ancient city wall conservation and was compared with other existing methods in effectiveness and accuracy. The results show that the proposed method can detect efficiently budging disease in ancient city walls for architectural heritage conservation.

Monitoring of stress distribution in damaged small-scale masonry walls by using two innovative sensors

Structural Health Monitoring (SHM) represents a strategic solution for the preservation of cultural heritage buildings. Existing masonry structures often suffer reductions in mechanical performances due to physiological aging of material constituents, external actions, and effect of catastrophic natural events. In many cases, the prompt prediction of damage in masonry elements is difficult and it can cause sudden collapses, compromising the safety of people.The proposed experimental study examines the effectiveness of two low-cost and innovative stress sensors, i.e. piezoelectric and capacitive stress sensors, for SHM of masonry structures. To this scope, the sensors were embedded in the mortar joints of two small-scale clay brick and calcarenite masonry wall specimens consisting of three panels. Experimental tests were carried out by applying a constant vertical compressive load at the top of each specimen and simulating the damage with a progressive reduction of the cross-section of one of the panels. During the tests, the vertical stress distributions (and their variations), were monitored by the sensors. Experimental outcomes from sensor reading were then compared to that numerically provided by a refined finite element simulation of the test. Results will show that vertical stress variations in masonry structures can be effectively accounted by the adopted sensors and potentially interpreted for the early prediction of structural damage.

Fibre reinforced mortars for the out-of-plane strengthening of masonry walls

Unreinforced masonry buildings (URM) often suffer of local out-of-plane failure mechanisms of the walls during a seismic excitation. This study investigates the effectiveness of a relatively novel class of inorganic composite materials, namely Fibre Reinforced Mortars (FRM), for the out-of-plane strengthening of masonry walls. Three experimental tests by using a novel setup to perform out-of-plane tests on masonry panels, part of an enlarged ongoing testing campaign, are presented herein. The specimens are solid clay brick masonry walls subjected to compressive axial load and out-of-plane horizontal actions according to a “four-point bending test” scheme. Two specimens are reinforced before testing with FRM, one in single-side and another one in double-side configurations, while the third specimen is tested in the bare configuration. Experimental results are reported and discussed. The preliminary results attest that FRMs are effective in increasing the out-of-plane capacity of masonry walls and in postponing the activation of the out-of-plane failure mechanism.

Computational modelling in a high rise building with different building envelope materials for sustainable living

This research focuses on identifying a sustainable material for building envelope for energy efficacy in naturally ventilated high rise residential buildings through CFD. Convective heat transfer is observed in three levels of the 14 storied highrise naturally ventilated building using three different building envelope materials ? burnt clay bricks, solid concrete block, and hollow concrete block. To artificially create the environment with CFD the different temperatures and velocities are used. The boundary conditions - initial outdoor temperatures 30 ?C and 23 ?C, respectively, were kept constant and the initial outdoor velocities 1 m/s to 10 m/s, were varied and simulated at 12 noon condition. Simulation results reveal, higher indoor temperatures in the roof exposed floor. At 30?C it is observed that there is a 0.2-0.3?C temperature difference between the burnt clay brick wall and the hollow concrete block wall through the varied velocities. In all cases of air velocities, the air temperature in the indoor spaces of the solid concrete block wall was found to be highest. This proves that solid concrete block wall has the highest conductivity and least resistivity over the other two materials. In the hollow concrete block, the process of conduction is slow and apparently the temperature in the indoor spaces is reduced. Thus, the results clearly indicate that the temperature in the indoor spaces of the hollow block building envelope was comparatively low when compared to the other two building materials.

Triaxial elastoplastic damage constitutive model of unreinforced clay brick masonry wall

Triaxial elastoplastic damage constitutive model of unreinforced clay brick masonry wall

Influence of MIWs on the seismic responses of moment resisting RCFs: A practical method

This study investigates the influence of masonry infill walls (MIWs) on the response modification factor of moment-resisting reinforced concrete frames (RCFs). To this end, several moment-resisting RCFs with a wide range of stories and bays are considered, and their base-shear versus roof-displacement curves are derived using incremental dynamic analysis. The frames are examined first with sixteen earthquake excitations, including the impact of masonry infill walls, and then without this effect. Four classes of clay brick masonry properties are utilized to cover a diverse range of masonry walls. Two cases are examined for infilled frames: in the first, all bays are infilled, and in the second, some bays in each story are infilled. The response modification factors of these frames are subsequently compared. The results indicate that MIWs significantly increase the secant stiffness and the strength of moment-resisting RCFs. The response modification factors of the infilled moment-resisting RCFs are found to be higher than those of bare frames. In addition, for most RCFs, the values of the response modification factor achieved for infilled moment-resisting RCFs are greater than the Iranian seismic code's prescribed value, whereas, for some bare frames, the code's recommended value is not met. Furthermore, several relations are developed to predict the response modification factors of infilled moment-resisting RCFs based on the bare frames' fundamental period and response modification factor. Four new frames subjected to seismic ground motions distinct from the primary earthquake excitations used to derive these relations and an experimental case are used to confirm their validity. Moreover, several graphs for the response modification factor of infilled frames with various clay brick masonry walls were developed. Using these graphs, building designers can determine the prism strength of MIWs required to meet the seismic code's prescribed value based on the fundamental period and response modification factors of bare moment-resisting RCFs.