Wall Elements Research Articles

A rapid machine learning-based damage detection algorithm for identifying the extent of damage in concrete shear-wall buildings

This paper presents a rapid machine learning-based damage detection framework for identifying the damage extent of concrete shear wall buildings. For this purpose, a parametric study was carried out to determine the most efficient machine learning algorithm in classifying the damage states of the building. According to this parametric study, the K-Nearest Neighbor (KNN) learner was selected as the reference prediction model because of the higher accuracy achieved by this algorithm. Bayesian Optimization (BO) algorithm was used to tune the hyperparameters affecting the accuracy of the model. The most efficient attributes were selected from the set of damage indicators through the BO algorithm to train the model. Three different benchmark buildings, including 7-,9-, and 13-story concrete shear wall buildings, were used to evaluate the robustness of the proposed framework. A suite of 111 pair motions, originally developed for the SAC project, were employed to create a generalized dataset. These motions were uniformly scaled from 0.05 g to 1.5 g to expand the intensity range of the events. All the acceleration signals were polluted to 10% noise using white Gaussian signals to simulate the field condition. Results reveal the efficiency of the proposed framework in identifying the extent of damage in concrete shear wall elements of the building. In addition, a parametric study was conducted to illustrate the reliability of two commonly used features, called Cumulative Absolute Velocity (CAV) and the energy ratio between the acceleration response and the input excitation, in determining the damage states of the shear walls under seismic motions.

Histopathological pulmonary findings of survivors and autopsy COVID-19 cases: A bi-center study.

The coronavirus disease 2019 (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), evolved into a global pandemic. As ACE2 on the surface of alveolar cells of the lung epithelium is one of the potential target receptors for SARS-CoV-2, the respiratory symptoms are the most common presentation of COVID-19. The aim of our study was to investigate the morphological findings in lung tissue after being infected by SARS-CoV-2 and compare histopathologic changes in patients with COVID-19 infection history who died to those who survived. We analyzed lung tissue samples from 9 patients who died from COVID-19 and from 35 patients with COVID-19 infection history who survived and had undergone lung surgery for different reasons. Most of histopathological changes in autopsy and survivors' cases overlapped; however, they occurred with different frequency. The predominant histologic finding both in the case of the deceased and the survivors was patchy distribution of foamy macrophages in the alveolar spaces. In comparison with autopsy cases viral cytopathic-like changes in hyperplastic pneumocytes were rarely observed in the survivors' lung tissue. Pulmonary edema, fibrin deposition within alveoli, bronchopneumonia, small vessel thrombosis and type II pneumocyte hyperplasia were also more often observed within autopsy cases. Life-threatening complications such as hyaline membrane formations and diffuse alveolar damage were present only within the deceased, whereas changes requiring enough time to progress to the fibrotic phase, such as organizing pneumonia, bronchiolization of the alveoli, and interstitial fibrosis were observed in the lung parenchyma only in survivors. Additionally, 14 cases of pulmonary pneumo-hematocele in patients with COVID-19 infection history who survived were observed. It is a newly observed entity in the form of a cystic lesion formed by large accumulation of blood and fibrin between the collapsed and rejected lung parenchyma and/or present with air-fluid levels. The thin wall of pneumo-hematocele is formed by the inter lobar interstitial fibroconnective tissue and has no epithelial lining or bronchial wall elements. As the COVID-19 pandemic continues, new complications following SARS-CoV-2 infection are identified. Newly observed entity in patients with COVID-19 infection history who survived is pulmonary pneumo-hematocele. The appearance of these lesion has become increasingly frequent.

Construction of indoor obstacle element map based on scene-aware priori obstacle rules

An obstacle element map is the basis of indoor navigation space subdivision. Effective and reasonable indoor space subdivision can improve the fineness of indoor navigation path planning. To divide an indoor navigation space more finely, an indoor obstacle element map construction method based on scene-aware a priori rules for obstacles is proposed. This method divides indoor space into navigable space (N-space), semi-navigable space (SN-space), and non-navigable space (NN-space) based on the flexible space subdivision framework (FSS) and classifies indoor obstacles into four categories, walls, doors, movable obstacles (MOs), and immovable obstacles (IMOs). First, by analyzing the layout and mobility of common indoor elements, the obstacle prior rules for seven types of indoor scenes (including hospitals, residences, classrooms, office buildings, transportation hubs, restaurants, and shopping malls) are formulated, and a method for obtaining obstacle prior rules based on scene recognition is proposed. Then, obstacles and their mobility are extracted from the semantic segmentation results of point clouds based on the acquired rules and mobility indicators. Finally, the extracted obstacles are processed to construct the obstacle element map, wall and door elements are fitted by the random sample consensus (RANSAC) algorithm, and IMOs and MOs are processed by Euclidean clustering. The experimental results show that the proposed method can effectively determine four types of indoor obstacles, and the overall accuracy in simple scenes is 85.22 %, while in complex scenes it is 97.96 %. Under the experimental environment (CPU: Intel Core i7-7700K; Memory: 16 GB and 2400 MHz; OS: Win10) in this paper, the construction of a simple scene obstacle element map can be completed in 5 s. In addition to the spatial information of the indoor elements, the obstacle element map also contains information about whether the elements can be moved, which provides the basis for the subdivision of the indoor space.

Study on in-plane compressive performance of cross-laminated bamboo and timber (CLBT) wall elements

Study on in-plane compressive performance of cross-laminated bamboo and timber (CLBT) wall elements

Thermal sensitivity and potential cooling-related energy saving of masonry walls through the lens of solar heat-rejecting paints at varying orientations

This study aims to analyse the thermal efficiency of wall elements with varying position-allocation-thickness of insulation, in the aspect of the optical properties of their external paint. A special focus has been placed on the role of solar reflectivity in wall coatings while taking into account the impact of the ambient environment at all cardinal points. In this light, the problem of urban environment warming must be addressed, while considering occupant reliance on air-conditioning. In the initial stage, the key research objective is to shed some light on the performance of analysed wall assemblies in terms of thermal sensitivity (decrement factor and time lag). On the other hand, at the targeting stage, our main intention is to demonstrate the eminence of solar heat-rejecting paints on the cooling power demand of wall arrangements. Furthermore, this work is extended to the assessment of the overall heating and cooling demands on an annual basis. A thermal-network model is developed within this framework to determine temperature variations and heat fluxes in the margins of the examined setups. The potential benefits of the suggested model are twofold. Accordingly, the findings of the numerical analyses reveal the configurations and operating conditions proving the optimal dynamic thermal parameters and energy demand. Numerical simulations indicate that an optimal cooling power capacity is noticeable for wall surfaces covered with solar heat-rejecting paints; cooling saving can exceed 90% for highly solar-reflective surfaces. However, when it comes to unveiling the global performability of ultra-white paints the overall improvement of conditions may vary radically; a reflective paint will probably not be sufficient to counterbalance both heating and cooling concerns. In terms of annual heat transmission loads, results exhibit an optimal solar absorptivity of 0.35 for north/east/west facing walls and 0.75 for south-oriented walls. Also, within the confines of our attention, by the increase of insulation level, the energy benefit can reach up to 40% per annum.

Industrial Waste Management: Economical Benefits of the Resource Utilization of Phosphogypsum

There are many publications in the literature on the reuse of waste gypsum in material production. In this study, in which the analysis of these existing publications is made through the determinations, the data examined are limited to the article and these are not included. However, to understand the general framework of the research in this field better, a few of these in the related literature are given below as examples. It is seen that industrial waste gypsum, which is a type of waste gypsum, has been examined more. Phosphogypsum, which is included in this waste group, reduces the water requirement for adjusting the cement consistency by adding phosphogypsum in cement production. As a result of the addition of phosphogypsum in wall element production, it was determined that the addition of phosphogypsum caused a decrease in mechanical strength, a decrease in unit weight and an increase in water requirement. It has been concluded that the addition of 15% phosphogypsum in soil stabilization of phosphogypsum, which is in the chemical waste class, causes an increase in water demand and pressure strength. In addition, 5.4% gypsum board waste with recycling potential is generated in the production of building elements made with waste gypsum boards formed at a construction site.

Concept of Sustainable Demolition Process for Brickwork Buildings with Expanded Polystyrene Foam Insulation Using Mealworms of Tenebrio molitor.

The traditional demolition process for brickwork buildings results in a significant volume of mixed debris. The debris consists of ceramic bricks (and other wall elements), mortar, thermal insulation (usually expanded polystyrene or rockwool), smaller steel elements, pieces of wood, and glass. Such mixed debris is difficult to recycle. Separating thermal insulation that is "glued" by cement mortar to brickwork is probably the most difficult and time-consuming task in processing mixed debris. This task can be performed in a very different and fully "automatized" manner using Tenebrio molitor mealworms. The mealworms remove expanded polystyrene from brickwork surfaces and transform it into frass. In the paper, a research program aiming to prove the concept of using the mealworms of Tenebrio molitor for processing mixed debris is presented. The tests were conducted using two models of a three-layered brickwork wall, which is very common in Europe. The proposed approached was successful. Both types of used expanded polystyrene foam (EPS) were fully removed from multilayer wall specimens. The possibilities and limitations of the proposed processing method were discussed and analyzed. The conducted research proved that it is feasible to clean brickwork debris from the EPS using Tenebrio molitor mealworms. Differences in the speed of cleaning process regarding the type of EPS were noted. More research is needed to scale the process, and to find the best method for using frass. By using Tenebrio molitor mealworms, one can make the demolition process much cleaner.

Thermal Effects of Vertical Greening in Summer: An Investigation on Evapotranspiration and Shading of Façade Greening in Vienna

Global urbanization is advancing, and with it, the densification of cities. Due to increased sealing of open spaces and the re-densification of existing urban settings, green spaces in the city are becoming scarcer. At the same time, greening within the urban fabric is known for its positive effects on the environment and decisively counteracts the urban heat effect. This study deals with the benefits of green façades for the environment as a cooling measure. Two façade greening systems, one trough and one cassette system, consisting of curtain wall elements with a basic metal structure, installed at a south-facing outdoor wall of a school building in Vienna, Austria, were taken under metrological examination. In order to evaluate the cooling effect caused by evapotranspiration, the amount of water evaporated was calculated using the difference of inflow and outflow. Furthermore, the surface temperatures of the greened and non-greened walls were measured to display the influence of the interaction of shading and evapotranspiration on the surrounding microclimate. The investigated vertical greening system with an area of 58 m2 has an average evaporation capacity of 101.38 L per day in the summer. The maximum surface temperature difference was measured to be 11.6 °C.

A Comprehensive Review on Cytoskeletal Organization and Its Interaction with Polysaccharides and Enzymes during Primary Cell Wall Development

A well-coordinated process is required to construct a complicated structure like the cell wall, which consists of several elements that must be joined appropriately from various sources inside the cell. In order to successfully moderate dynamic responses to developmental and environmental signals, further complexity is necessary. The plasma membrane is continually and actively transporting sugars, enzymes, and other cell wall elements throughout diffused development. Actin filaments and microtubules make up the cytoskeletal pathways used to transport cell wall elements in vesicles during cell division. In addition to these elements, other proteins, vesicles and lipids are transported from and to the cell plate while cytokinesis occurs. Adding additional cell wall material or building a new cell wall requires a rearrangement of the cytoskeleton, which we examine in this review first. We next look at the commonalities between these two processes. Our next topic is the transport of cell wall-building polysaccharides and enzymes via motor proteins and other interactions with the cytoskeleton. Final thoughts on cytokinesis-generated cell walls include a look at some of their unique properties.

An experimental study of the stiffness and strength of cross-laminated timber wall-to-floor connections under compression perpendicular to the grain

In platform-type multi-story cross-laminated timber (CLT) buildings, gravity loads from upper floors, and vertical reaction forces from horizontal actions, like wind loads, cause substantial compressive forces in the CLT-floor elements. The combination of these high forces with a comparable low compression stiffness and strength perpendicular to the grain of timber, makes the compression perpendicular to the grain (CPG) verification of CLT an important design criterion. In this experimental study, CPG of CLT was investigated by means of typical wall-to-floor connections in CLT platform-type structures. CLT-wall elements were used for load application to transmit forces through the CLT-floor element by CPG. Compared to load application by steel elements, as it commonly is done in experiments, lower stiffness but similar strength were found for CLT walls. The study of different connection types showed the highest stiffness and strength for connections assembled with screws, followed by pure wood-to-wood contact, while connections with acoustic layers between the floor and wall elements showed the lowest stiffness and strength. In addition, these connections were tested for center and edge load position on the CLT-floor element. The strength for center and edge position compared to full surface loaded specimens increased linearly with the activated material volume, as determined by earlier proposed stress dispersion models. The stress dispersion effect was visualized by surface strain measurements using digital image correlation technique. Also, the stiffness increased with the activated material volume. Stress dispersion in the CLT-floor allowed to explain the increase in stiffness and strength with decreasing CLT-wall thickness. Strength values at different strain levels, and stiffness and strength increase factors suitable for the engineering design of CLT structures are provided.

Fine Characterization Method of Concrete Internal Cracks Based on Borehole Optical Imaging

The internal cracks of concrete are very important in the safety evaluation of structures, but there is a lack of fine characterization methods at present. Borehole cameras are a piece of in situ borehole detection technology which can measure the structural elements of a borehole wall with high precision. In this paper, borehole camera technology is used to measure the concrete cracks of a tunnel floor, and the morphological characteristics (depth, width, and orientation) of the cracks are analyzed. The results show that the average extension depth of the crack extending from the orifice exceeds 1.195 m, and the width decreases with the increase in depth. The crack orientation is basically stable, with the maximum deviation of 19° at the orifice of different boreholes and 30° at different depths of the same borehole. The crack inside the concrete (not extending to the orifice) usually has a small extension depth and a relatively stable width, but the crack orientation changes greatly. The coarse aggregate and concrete interface have different effects on the extension direction of cracks. This paper also conducted a second measurement on two of the boreholes after an interval of 15 days, and found the difference in crack development in the two measurements. The work of this paper provides a new attempt for the detection and monitoring of concrete crack morphology.

Effect of insulation thickness on energy saving in cold regions of Türkiye

In the countries procuring a major amount of their energy from abroad, using of the energy effectively and ensuring the energy-saving become gradually more important. In this study, considering the climatic and meteorological conditions of Van province, optimum insulation thickness, payback period, and energy-saving values were analyzed for three insulation materials (rock wool, polyurethane, XPS) and five energy sources (imported coal, fuel oil, LPG, natural gas and electricity) on wall models built with pumice and aerated concrete. The optimum insulation thickness was calculated using the interest and inflation rates. The calculations were made by making use of the lifecycle cost analysis (LCCA). Insulation thickness that should be applied depending on the wall elements used in buildings can vary. Thus, examining the wall models, insulation materials and energy sources were examined, and the optimum insulation thicknesses, annual savings, and payback periods were found to be 3-15.6 mm, 30-63%, and 1.4-5.8 years, respectively, in the present study.

Numerical study of racking resistance of timber-made double-skin facade elements

The use of a double-skin façade (DSF) is a quite new approach in the building renovation process, complementing conventional renovation strategies. A double-skin façade is an envelope wall construction that consists of two transparent surfaces separated by a cavity and can essentially improve the thermal and acoustic resistance of the building envelope. The main double-skin wall components are usually composed of a hardened external single glazing pane and a double or triple thermal insulating internal glass pane, which are connected to the frame structure. Recently, many studies have analysed the thermal and acoustic performance of DSF elements, but almost none in terms of structural behaviour, especially in terms of determining the racking resistance of such wall elements. Moreover, with a view to reduce the global warming potential, an eco-friendly timber frame instead of a commonly used steel, aluminium or plastic frame is studied in this analysis. However, structurally combining timber and glass to develop an appropriate load-bearing structural element is a very complex process involving a combination of two materials with different material properties, where the type of bonding can be selected as a crucial parameter affecting the racking resistance range. Since the costs of experiments performed on such full-scale DSF elements are very high and such experiments are time-consuming, it is crucial to develop special mathematical models for analysing the influence of the most important parameters. Therefore, the main goal of this paper is to develop the finite element mathematical model of the studied DSF structural elements with a highly ecological solution by using a timber frame. In the second step, the developed model is further implemented in the numerical analysis of racking stiffness and followed by a comprehensive parametric numerical study on different parameters influencing the horizontal load-bearing capacity of such DSF timber elements. The obtained results indicate that the new approach of the developed load-bearing prefabricated timber DSF elements can essentially improve racking resistance and stiffness compared with the widely studied timber-glass single-skin wall elements and can thus be fully recommended especially in the structural renovation process of old buildings.

Study of the Influence of the Opening Size and the Type of Reinforcement on the Behavior of the Reinforced Concrete Infill Shear Walls

The subject of the article is a comparison of behavior of a precast reinforced concrete infill shear walls with an opening with different types of reinforcement. These are the walls that can ensure stiffness of the frame structure against horizontal load. Studied walls with an opening represent cases of how the wall can be reinforced prior to the implementation of an additional opening. The influence of the so called “sleeping reinforcement” is studied. This is a reinforcement that would take effect only after the additional opening has been made. The wall elements are first subjected to experimental verification. Subsequently, the results from the experiments are verified by non-linear models, which represent the individual elements during the experiment. Based on these models, a parametric study is performed, where the influence of an opening size in these infill shear walls is studied on their load - bearing capacity and stiffness.

Modeling of thermal storage enclosure with applying finite element method in presence of nanomaterial

In this article, trapezoidal enclosure has been involved with applying three-lobed inner cold wall and finite element method was utilized in order to simulating this unsteady problem. The all walls except the vertical ones are cold and domain was full of liquid water. Inclusion of nano-powders was assumed as technique of accelerating the solidification in this article. Moreover, the efficacy of shape of alumina nano-powders on expedition of process has been simulated. As nanoparticles added to water, required time declines around 5.97 %. Also, change of particle style to platelet shape results in reduction of period of freezing around 11.56 %. The particles with higher m can affect freezing more about 2.5 % than that of m = 3. The quickest process takes 688.39 s to be completed when m = 5.7, ϕ = 0.04.

Thermal Insulation Performance and Reliability of the “Structure-Insulation” Integrated Wall Panel (SIW) for Storage Grain Bungalows

The traditional brick bungalow is not conducive to long-term grain storage because of its poor thermal insulation. In this paper, a new type of wall element for grain bungalows with both load-carrying and thermal insulation functions, called a “Structure-Insulation” integrated wall panel (SIW), is proposed for improving the grain storage environment. To study the thermal insulation reliability of SIW under multivariable randomness and the availability of different grain storage zones, a finite element model was established based on the test. Then, the failure criterion was established with the heat transfer coefficient as the key point and 1,000,000 sampling calculations were carried out by the Monte Carlo method. The reliability was discussed and sensitivity of random parameters was quantified. The thermal performance test shows that the heat transfer coefficients of the two designed SIW wall panels compared with the traditional brick bungalow wall are reduced by 45.81% and 56.13%, respectively. The thickness of the insulation panel is sensitive mostly to the thermal insulation performance, with a correlation coefficient of 0.877. When the thickness of the insulation panel is 80, 94, and 107 mm, the wall panel can meet the limit requirements of the heat transfer coefficient of the granary enclosure structure of 0.59, 0.53, and 0.46 W/m2·K, with reliability indexes of 3.08, 1.82, and 1.75, respectively. The research results provide an important reference for the design, optimization, and application of SIW wall panels in thermal insulation.

Stiffening controllable concrete modified with redispersible polymer powder for twin-pipe printing

To achieve stiffening control in 3D concrete printing, a twin-pipe pumping (TPP) system has been developed, where two streams of cementitious materials are pumped separately via two pumps and blended over a helical static mixer right before extrusion. However, in addition to the interlayer region, the presence of striations consisting of unmixed limestone-based regions reduces the mechanical integrity of printed elements in earlier research on TPP strategy making use of a cement-based mixture and a limestone-based mixture. In this work, we examined the use of redispersible polymer powder (RDP) as a means to improve the mechanical performance of such 3D printed elements. Limestone powder in the limestone-based mixture was partially substituted by different dosages of redispersible polymer powder (5, 10, and 15 %). Rheological behavior of the cement-based mixture and the limestone-based mixture was evaluated. Further, we studied the effect of RDP addition on the hydration and the early age mechanical behavior of the combined mixtures. In the hardened state, specimens extracted from 3D printed wall elements were tested for flexural, compressive, and tensile strength. Its microstructure was examined using scanning electron microscopy. From the results of various studies conducted, although adding redispersible polymer powder would slightly reduce the very early age mechanical strength, it enhances the mechanical integrity in the hardened state due to film formation in the limestone-based mixture.

METODE IDENTIFIKASI KERUSAKAN ELEMEN FISIK BANGUNAN HERITAGE DENGAN BUILDING INFORMATION MODELING (BIM) STUDI KASUS ISTANA ALWATZIKHOEBILLAH SAMBAS

Heritage buildings as architectural heritage assets that describe the identity of a region and the architecture of the past are important to be conserved and maintained. One of the cultural heritage buildings in Indonesia is Alwatzikhoebillah Sambas Palace. This building was built with wood construction. The condition of wood with age will experience changes in characteristics due to its interaction with various factors, especially biological and non-biological factors. Changes in any form cannot be underestimated, so documentation of cultural heritage buildings is needed. One way of documenting cultural heritage buildings is Building Information Modeling (BIM). BIM documentation can record various building information that is inputted in it. This research aim was to mapping and assessing the damage to the physical elements of wood on one of the accompanying buildings on the north side of the Alwatzikhoebillah Palace using BIM. BIM information contains the color code, mapping code, and the extent of the damage that occurs in the 2D view. The variables of this study were limited to biological damage caused by fungi and moss, also non-biological factors due to mechanical, weather, and chemical factors. The results of this research is the wall elements are dominantly damaged caused by wood staining fungus or mechanical erosion and weather changes of 1,64% with the effect of gray stains left on the elements.

On global and local buckling response of structural angle sandwich panels

Having in mind the topic of industrialised construction and the benefits of modular construction, sandwich panels are investigated to be utilised as load-bearing wall elements. To assess its full potential, the present paper tackles the linear elastic buckling response of axially loaded angle sandwich panels, by means of numerical and analytical calculations, as the upper bound of its load bearing capacity. The failures modes are obtained and framed for concentrically loaded angle panels with fixed and pin-ended supports. A parametric study of the angle panel comprising a series of finite element models is undertaken where responses are compared with analytical calculations based on the theory of sandwich panels. Boundaries for local and global buckling are identified and framed.

Analysis of Load Deformation Behaviour of CSFRC Arc Corbel Using ANSYS

Abstract: Corbels are the structural members that transfer the horizontal and vertical load from beams to wall or column element. Corbels projecting from the faces of reinforced concrete columns are extensively used in precast concrete construction to support the primary beam and girders. Corbels are structural members characterized by a shear span-to-depth ratio (a/d), generally lower than unity. Arc corbel has better stress performance than other shaped corbel and also bear the crane loads. It is provided to support rails and support the end spans of the double cantilever balanced reinforced concrete bridges. Corrugated Steel Fiber Reinforced Concrete(CSFRC) is a concrete with short, discrete lengths of steel fibers which are randomly dispersed. This paper illustrates the effect of shear span-to-depth ratio on load deformation behavior of Corrugated Steel Fiber Reinforced Concrete arc corbel. The structure thatgenerates comparatively small deformation within the applied load can be considered as relatively safe. Corrugated Steel Fiber Reinforced Concrete with 1% steel fiber is used in the current study. The shear span-todepth ratios adopted for the study are 0.1, 0.15, 0.2. The analysis of the structure has been carried out using ANSYS Software.