Hollow Brick Walls Research Articles

Behavior of hollow clay brick masonry walls during fire. Part 2: 3D finite element modeling and spalling assessment

In the first part of this work [1], the fire behavior of masonry walls made with hollow fired-clay bricks was investigated experimentally. Several complex mechanisms occurred during firing are analyzed and identified. In particular, in cases of load-bearing walls, the local spalling of bricks is considered as an important factor governing the fire performance of masonry walls.In this second part, fired-clay masonry is investigated by theoretical approach with the finite element method in order to predict its behavior and its performance under fire exposure. For this purpose, a 3D numerical simulation is conducted with paying a particular attention to the spalling risks of alveolus bricks.

Sustainability assessment of an innovative lightweight building technology for partition walls – Comparison with conventional technologies

The growing necessity to save material and energy resources, together with an increasing concern over the environmental issues and uncertainties on the evolution of the economy, have impelled minimalist-approaches to Architecture and Engineering. This created a new necessity for reducing, to the minimum necessary expression, the used building materials and elements. When analysing the overall material inputs of a building, it is possible to conclude that the interior partition walls have the higher contribution to the material inputs, when compared to other non-load bearing construction elements. Other aspect to highlight is that a great portion of building designs are not flexible in use and therefore buildings are not suitably adjustable to the permanent updating of life-styles and variations on the composition of the households. Although there are some lightweight building technologies, in most cases the construction practice all over Europe makes use of heavyweight and static partition walls. This paper will focus the advantages of lightweight partition walls and may contribute for the development of new partition wall technologies. It presents a sustainability assessment of a new lightweight sandwich membrane building technology for indoor partitions developed within a research project. The used methodology comprises the environmental, functional and economic life-cycle analysis. In order to identify the advantages of the building technology under development, each different design approach for the conceptual technology will be compared with two reference technologies: i) the heavyweight conventional partition wall (hollow brick wall); and ii) the lightweight reference gypsum panels wall (plasterboard wall).

Development of a hybrid wave based–transfer matrix model for sound transmission analysis

In this paper, a hybrid wave based-transfer matrix model is presented that allows for the investigation of the sound transmission through finite multilayered structures placed between two reverberant rooms. The multilayered structure may consist of an arbitrary configuration of fluid, elastic, or poro-elastic layers. The field variables (structural displacements and sound pressures) are expanded in terms of structural and acoustic wave functions. The boundary and continuity conditions in the rooms determine the participation factors in the pressure expansions. The displacement of the multilayered structure is determined by the mechanical impedance matrix, which gives a relation between the pressures and transverse displacements at both sides of the structure. The elements of this matrix are calculated with the transfer matrix method. First, the hybrid model is numerically validated. Next a comparison is made with sound transmission loss measurements of a hollow brick wall and a sandwich panel. Finally, numerical simulations show the influence of structural damping, room dimensions and plate dimensions on the sound transmission loss of multilayered structures.

Microclimate Variations with Wall Configurations for Chinese Solar Greenhouses

Five greenhouses with different typical wall configurations were studied, including the hollow brick wall (HB), clay brick wall composed of mural column (MCCB), wall composed of fly ash air block brick (FAABB), clay brick wall composed of plum small hole column (PSHCCB), common clay brick wall with Styrofoam wall outside (SCB) to find out the effects of the north walls on the greenhouse microclimate. The interior temperature and RH environment, as well as the heating rate, cooling rate and the correlation with the outside temperature, were tested and compared, finding that the greenhouse with FAABB exhibits the optimal temperature and RH environment, and also the highest thermal stability. The findings may provide references for greenhouse construction and insulation measures.

The 2011 Earthquake in Simav, Turkey and Seismic Damage to Reinforced Concrete Buildings

Reinforced concrete buildings suffered significant damage in the region affected by the 29 May 2011 earthquake in Simav (Kutahya), Turkey. Typical building damage is classified and potential causes of damage are investigated. Reinforced concrete moment resisting frames with hollow brick infill walls are the most common structural system in and around the Simav city center while masonry construction is common in rural areas. Although the Simav earthquake, with a magnitude of 5.7 to 5.9, can be classified as a moderate earthquake, many buildings experienced damage varying from frequent diagonal cracking and brittle failure of infill walls to collapse or severe damage to frames due to short columns, soft stories or other reasons including insufficient or poor detailing of reinforcement. This study investigates and presents the seismicity of the region, characteristics of the measured ground motions, seismic load demands including response spectra, and damage mechanisms, potential causes and classification of observed damage in reinforced concrete buildings.

Modelling of strengthened hollow brick infills

Strengthening the existing hollow brick infill walls by bonding high-strength precast concrete panels or applying steel fibre reinforced mortar was found to be an occupant-friendly seismic retrofitting technique for the buildings in use with deficient reinforced concrete structural systems. Both techniques convert the existing non-structural hollow brick infill walls into load-carrying structural members. To verify the effectiveness of the techniques, 20 reinforced concrete frames with hollow brick infill walls were tested under reversed cyclic lateral loading simulating earthquake. In the present study, hollow brick infill walls strengthened by these techniques were modelled by means of two equivalent diagonal struts in the analytical studies. Analytical results matched well with the experimental results. A performance-based rehabilitation case study of an existing building showed that both techniques offer a sound and practical solution for rehabilitation studies.

Experimental and Numerical Identification of Lamb Waves in Hollow Brick Walls

Experimental and Numerical Identification of Lamb Waves in Hollow Brick Walls

Experimental Study on Seismic Stability of Shear Wall by Laying Insulated Shale Hollow Brick outside

Based on the low cyclic reversed lateral loading tests of shear wall thermal insulation brick wall on build by laying bricks, shale brick masonry wall thermal insulation of the failure pattern, deformation and stability and seismic performance ability and shear wall deformation, the seismic performance were analyzed. The results of the study show that the shale hollow brick wall insulation bricks with a good seismic performance stability. If vertical slits were set properly, the transformative property of the shear wall was improved greatly and the seismic behavior was excellent under the condition that the bearing capacity decreased slightly.

Retrofit of Non-Ductile RC Frames with Precast Concrete (PC) Wall Panels

An economic, structurally effective and practically applicable strengthening method had been developed for reinforced concrete (RC) framed buildings. This study presents the test results on strengthening of deficient RC frames by using high strength precast concrete (PC) panels. The idea of the method is to convert the existing hollow brick infill wall into a load carrying system by bonding PC panels on to the plastered hollow brick infills. For this purpose, six (two reference and four strengthened) one-third scale, one bay, two storey deficient RC frames were tested under reversed-cyclic lateral loads. Test frames were designed and constructed with common deficiencies observed in practice. Panels having two different shapes were used as strengthening agencies. Test results showed that both strength and stiffness of the test frames were significantly improved by the introduction of PC panels. Experimental results were compared with the analytical approaches suggested by the authors.

Characteristics of CFRP retrofitted hollow brick infill walls of reinforced concrete frames

The mechanical characteristics of infill walls retrofitted with carbon fiber reinforced polymer (CFRP) sheets are really important for the realistic prediction of seismic performance of the vulnerable reinforced concrete (RC) frames retrofitted through CFRP strengthened infill walls. In this study, 36 hollow brick wall specimens were tested either under uniaxial compression or diagonal tension before and after retrofitting externally with CFRP sheets. The test parameters are the dimensions of the walls, the orientation of holes of bricks, the type of mortar, the amount of CFRP sheets and the details of strengthening application. At the end of the tests, a significant contribution of CFRP sheets on the mechanical characteristics of hollow brick walls was observed in terms of several important structural design parameters such as Young and shears moduli, axial and shears strengths as well as the deformation capacity. Finally, the strength and deformability characteristics of the walls and frames retrofitted with CFRP sheets were predicted analytically. The predictions were in good agreement with the experimental data.

Seismic strengthening of reinforced concrete frames by precast concrete panels

An innovative occupant-friendly retrofitting technique has been developed for reinforced concrete (RC)-framed structures which constitute the major portion of the existing building stock. The idea is to convert the existing hollow brick infill wall into a load-carrying system acting as a cast-in-place concrete shear wall by reinforcing it with relatively thin high-strength precast concrete panels epoxy bonded to the plastered infill wall and epoxy connected to the frame members. In this study, results of 11 one-third scale, one-bay, one-storey RC frames, tested by the authors, having the deficiencies commonly observed in residential buildings in Turkey, tested under reverse-cyclic lateral loading until failure are given in detail. It was clearly observed that the seismic performance indicators such as strength, lateral stiffness and energy dissipation capacity of the strengthened frames were significantly improved by the proposed technique.

A homogenised vibratory model for predicting the acoustic properties of hollow brick walls

The prediction and the physical understanding of sound transmission through masonry walls made of hollow bricks remain an open question. To solve this problem a semi-analytical approach is proposed. The inhomogeneous structures of the brick wall are homogenised and a simplified analytical model is established to calculate the transmission loss of an equivalent finite and multilayered anisotropic plate. An efficient numerical homogenisation technique is derived to define the equivalent anisotropic brick. This process only needs the knowledge of the elastic tensor of the brick material that has been determined using ultrasonic measurements. The features of the simplified brick wall have been then investigated through Lamb waves dispersion curves. Finally, the model has been used to explain the transmission loss curve of a wall and a good agreement between predictions and test data is obtained.

Strengthening of deficient RC frames with high strength concrete panels: an experimental study

An economic, structurally effective and practically applicable strengthening technique was developed for reinforced concrete (RC) framed buildings. The idea of the technique is to convert the existing hollow brick infill wall into a load carrying system acting as a cast-in-place RC infill wall by bonding relatively thin high strength precast concrete PC panels to the plastered hollow brick infill. For this purpose, a total of eight one-third scale, one bay, one story frames were tested under reversed-cyclic lateral loads. Test frames were designed and constructed with common deficiencies observed in practice. Four different panel types were used for strengthening. Test results showed that both strength and stiffness of the frames were significantly improved by the introduction of PC panels. Experimental results were compared with the analytical approaches suggested by the authors.

Lightweight Dividing Walls: Adaptation to Temperate Climates

This paper intends to prove that it is possible to use lightweight membranes on interior partition walls and on external facades, even in housing buildings at temperate climate regions, if their properties are well explored. The few material used, even less than conventional lightweight solutions the most common is plasterboard with light steel frame structure allow a lower specific embodied energy and other more favourable environmental impact indicators. Compared to conventional heavyweight solutions, such as hollow brick walls, lightweight membranes allow easier deconstruction/reuse. In the outer skin, architectural membranes can be used as passive or active systems, for heating (promoting greenhouse effect) and cooling (shading or even evaporative cooling). Lightweight materials are more viable to be used on invariably hot or cold climates, than on temperate climates, as in this context they present problems related with its low thermal storage capacity. However, the research of new architectural membrane materials, with passive and active behavior for thermal regulation, allows extending its possibilities to interior dividing partitions in order to fulfill contemporary demands of comfort. Active and/or passive systems can be used to regulate thermal gains – for example by radiant panels and/or evaporative cooling, but also to achieve thermal inertia. In pavements, thermal storage lightweight elements, using natural Phase Change Materials, were already studied and reported on previous studies from the first author. Examples of how these systems can also be applied to lightweight membrane dividing walls are presented in this paper, and some experimental research is now under course on test cell facilities existing in University of Minho, Guimaraes.

Seismic Strengthening with Precast Panels - Theoretical Approach

An economical, structurally effective and practically applicable seismic retrofitting technique has been developed on the basis of the principle of strengthening the existing hollow brick infill walls by using high strength precast concrete panels. The technique would not require evacuation of the building and would be applicable without causing much disturbance to the occupant. For this purpose, eighteen one-bay two-story reinforced concrete frames with hollow brick infill walls were tested under reversed cyclic lateral loading simulating earthquake. The specimens were strengthened by using six different types of precast concrete panels. In the present study, hollow brick infill walls strengthened by using high strength precast concrete panels were modeled once by means of equivalent diagonal struts and once as monolithic walls having an equivalent thickness. The experimental results were compared with the analytical results of the two approaches mentioned.

Sound transmission loss analysis through a multilayer lightweight concrete hollow brick wall by FEM and experimental validation

This research work tries to find the most efficient numerical procedure to predict the transmission loss (TL) through a multilayer wall for frequencies ranging from 100 to 5000 Hz. The wall is made of lightweight concrete hollow bricks joined by mortar, with gypsum lining on both faces. This study is motivated by the need to develop new products with better acoustic properties of airborne sound insulation. In order to achieve this objective a set of tests using source and receiving chambers have been modelled according to the basic requirements of the UNE-EN ISO 140-1 standard rule. The constructive element is located between both chambers in order to evaluate its acoustic behaviour according to the UNE-EN ISO 717-1 standard rule. Applying the finite element method (FEM), a two-dimensional model with fluid-structure interaction has been built in the case of the horizontal and vertical planes, with the purpose of including the different eigenfrequencies of the rooms. The values of the average sound pressure in both test chambers have been calculated for different excitation sources: uni and omnidirectional waves. The convergence and accuracy of the proposed method are then assessed by comparing FEM results with experimental measurements carried out by a certified laboratory. Finally, the numerical procedure implemented in this work may be useful to evaluate the acoustic behaviour for other structural building elements and reduce the manufacturing time to develop new products in construction.

Static and dynamic thermal characterisation of a hollow brick wall: Tests and numerical analysis

This article explains the adjustment procedure of a calibrated hot-box unit and the execution of the corresponding tests to measure the dynamic thermal properties of walls needed to calculate the thermal load of buildings. The results of a test for a heterogeneous wall are also presented, in a dynamic temperature rating. These results are compared with those obtained from a simulation carried out on the performance of the same wall through the application of a finite volume software. Subsequently, the error introduced by assuming one-dimensional heat flow through a nonhomogeneous wall is discussed. This is equivalent to considering the heterogeneous layer of the wall as an equivalent homogeneous layer, which is done in several whole building simulation programs. It is concluded that the error committed may be appreciable, even when the heterogeneities are not excessive.

Nonlinear thermal optimization of external light concrete multi-holed brick walls by the finite element method

In this work, an analysis and numerical study have been carried out in order to determine the best candidate brick from the thermal point of view by the finite element method. With respect to the ecological design and the energy saving for housing and industrial structures, there is also a great interest in light building materials with good physical and thermal behaviours, which fulfils all thermal requirements of the new CTE Spanish rule for further energy savings. The conduction, convection and radiation phenomena are taking into account in this study for four different types of bricks varying the material conductivity obtained from the experimental tests. Based on the previous thermal analysis, the best candidate was chosen and then a full 1.05×0.35×1.0m. wall made of these bricks was simulated for fifteen different compositions and temperature distribution is also provided for some typical configurations. The major variables influencing the thermal conductivity of these walls are illustrated in this work for different concrete and mortar properties. The finite element method (FEM) is used for finding accurate solutions of the heat transfer equation for light concrete hollow brick walls. Mathematically, the nonlinearity is due to the radiation boundary condition inside the inner recesses of the bricks. Optimization of the walls is carried out from the finite element analysis of four hollow brick geometries by means of the average mass overall thermal efficiency and the equivalent thermal conductivity. In order to select the appropriate wall satisfying the CTE requirements, detailed instructions are given. Finally, conclusions of this work are exposed.

Technical Note: Airborne Sound Insulation of Hollow Brickwork

This paper reports on the uncertainty of in situ measurements of the airborne sound insulation of hollow-brick walls in different housing plans, with emphasis on the influence of expansion joints. The mean and standard deviation of multiple measurements are obtained, which show significant differences in insulation values despite the fact that the same construction was used in each case.

Analysis and design of FRP composites for seismic retrofit of infill walls in reinforced concrete frames

There is an urgent need to retrofit deficient mid-rise reinforced concrete (RC) frame buildings in Turkey. For this purpose, an efficient FRP retrofit scheme has been developed previously, in which hollow clay brick infill walls can be utilized as lateral load resisting elements after retrofitting. The main premise of this practical retrofit scheme was to limit inter-storey deformations by FRP strengthened infill walls that are integrated to the boundary frame members by means of FRP anchors. Based on the analytical model that was previously verified extensively by comparison with test results, a simplified model was proposed for use in displacement based design of FRPs for deficient RC frame buildings. FRP retrofit design and analysis of an actual deficient RC building located in Istanbul are presented herein both for the local design spectrum and Duzce ground motion. It was observed that the FRP retrofit reduced the damage induced to deficient columns by controlling story deformations. In this way, it was possible to satisfy the collapse prevention performance state in an efficient and economical manner.