Outer Wall Of Building Research Articles

Data image correlation analysis of the destruction process of 3D printable layered beams subjected to the 3-point bending process

Technological processes and materials related to Additive Manufacturing (AM) are gaining popularity in civil engineering 3Dconcrete printing is aimed mainly at the process of rising the inner and outer walls of buildings. In these elements, the main load is axial compression with a low fraction of bending. The 3D-printing process of cement-based materials provides the construction elements with appropriate compressive strength. Although creating elements, which can carry the tensile loading is necessary to make the 3D-printing process used in civil engineering. Therefore, this paper aims to show the response of the 3D-printed cement-based composites to the bending process to find the effect of complex layered structures on their effective properties. Instead of the standard use of an extensometer to obtain Crack Mouth Opening Displacement results, novel Digital Image Correlation measurement technology was used during research. This technology allows for continuous real-time measurements that are extremely difficult when testing brittle materials such as concrete and avoids the additional introduction of external forces caused by the classical measuring device. The proposed AM material contains the interlayer polymeric net and smeared polymeric reinforcement to enhance flexural strength. The use of the polymeric net and smeared reinforcement introduces residual strength into the composite allowing for its further work after brittle phase failure. However, the obtained results showed that analysed layered beams had decreased interlayer resistance. The process of layer cracking occurs subsequently layer by layer and the failure in different layers developed as an independent process including cracks arresting.

Closed-cell polyurethane spray foam obtained with novel TiO2–ZnO hybrid fillers – mechanical, insulating properties and microbial purity

Much attention is currently being paid to organic-inorganic composite materials and their unique physicochemical and functional properties. In the present work, for the first time, it is investigated how the incorporation of inorganic oxide fillers affects the mechanical and insulating properties and microbial purity of building materials, closed-cell polyurethane spray foam (for insulation and sealing of ceilings and walls: including attics – the inner side of the roof and even the outer walls of buildings). Two types of inorganic oxide fillers, TiO2 and TiO2–ZnO synthesized via a sol-gel method, were used. The physicochemical properties of the fillers were evaluated, including dispersion, morphology, textural and crystalline structure, and chemical composition. The main objective of the research was to evaluate how the addition of fabricated inorganic fillers (in amounts of 1, 2.5, 5 and 10 wt%) affects the functional properties of closed-cell polyurethane spray foam. The results indicate that the incorporation of inorganic oxide fillers into the polyurethane matrix improves the strengthand thermal properties of the foams (even over time). Moreover, materials constructed using closed-cell polyurethane spray foam and inorganic oxide fillers offer good application potential. In particular, the synthesized TiO2–ZnO hybrid system provides the possibility of modulating the PUR (polyurethane) foam structure in terms of the number and size of pores (reduction of the average pore diameter by approximately 20% – compared to the reference sample). Consequently, it can significantly increase the density (32.2–36.3 kg/m3), strength (about 10% compared to the reference sample), structural stability, microbial purity of the material and maintain a high level of insulation (reference sample 0.0222 W/(m.K) and sample with the addition of 5 wt% of TiO2–ZnO – 0.0215 W/(m.K)). The obtained spray foam can be used as innovative insulating construction coatings. The use of such materials will ultimately have an impact on the indoor environmental quality.

A Novel Strategy for Monitoring a PV Junction Box Based on LoRa in a 3 kW Residential PV System

Recently, 3 kW residential PV (Photovoltaic) junction boxes have mainly been installed on the roof or outer wall of building. Wired and wireless monitoring systems are being implemented by RS-485 and WIFI/IoT. However, conventional monitoring systems have a communication limitation according to the distance and environment. It cannot receive any information when a failure of the PV junction box occurs. Therefore, there is a need for a strategy to determine whether the fuse and diode in the PV junction box are faulty through voltage and current sensors. In this paper, we propose a novel strategy for monitoring PV junction boxes, based on LoRa (Long Range). The TTGO LoRa32 V2.0 module with LoRa and various input and output ports is utilized. The wireless TX module transmits various data collected from the PV junction box to the RX module in real time. In addition, the RX module displays the received data on an LCD (Liquid Crystal Display) screen so that the user can intuitively identify it, and the data is recorded on the internal storage device or database in the web server. The manufactured PV junction box monitoring system was tested under a 3 kW PV system. Additionally, communication reception has stable signal intensity overall, both indoors and outdoors. In particular, it shows excellent characteristics in maintaining RSSI (Received Signal Strength Indicator) > −99 dBm and PER (Packet Error Rate) < 2.7%, up to a radius of 200 m, even in NLOS (Non Line-Of-Sight) environments. Although some packet loss occurred, it was confirmed that invisible communication was possible up to 300 m.

НЕСУЩАЯ СПОСОБНОСТЬ И ДОЛГОВЕЧНОСТЬ НАРУЖНЫХ КИРПИЧНЫХ СТЕН ЗДАНИЙ

For buildings of historical development of cities, as well as architectural dominants of urban and rural settlements, the architectural attractiveness of buildings is often created by erecting external load-bearing brick walls, including multilayer ones, as well as curtain external walls with a finishing layer of facing bricks. When designing building envelopes, as well as in the process of researching and assessing the technical condition of building envelopes, it becomes necessary to calculate (assess) the bearing capacity of external walls, to assess their durability. The object of research is the bearing capacity and durability of the outer walls of buildings. A review of domestic and foreign scientific and technical literature has been carried out. He showed that the overwhelming majority of scientific publications concern the choice of constructive solutions for walls, the purpose and use of new building technologies and materials, their technical characteristics, as well as the assessment of the energy efficiency of the proposed constructive solutions for external walls. Examples of defects in the outer layer of multilayer bearing walls of brick buildings and recommendations for ensuring the durability of the front layer of a brick wall are given. The requirements of the current building codes for calculating the bearing capacity of multilayer brick walls are considered. An example of calculating an eccentrically compressed multilayer brick wall with equivalent calculated cross-section is given. In order to simplify the calculation of the bearing capacity, it is proposed to use computer programs to determine the geometric characteristics of the equivalent calculated cross-section. In particular, for a short-term application of loads to determine the stresses and analyze the stress state of the equivalent calculated cross-section of the wall, an example of using the program, the constructor of sections PK LIRA-SAPR, is given. It is shown that it is necessary to consider the distribution of stresses over the section under short-term and long-term loading in the design of multilayer brick walls.

Thermophysical properties of light Polemer silicat shyngisite concrete in natural conditions

The development of methods for protecting the structures of external walls from corrosion under the influence of the aggressive production environment is an urgent task. The author has developed lightweight polymer silicate shungizite concrete (LPSC) for external walls of buildings with acidic humid gas environments. Exterior wall structures made of this material do not need to be protected by paint and varnish coatings. The properties of LPSC were investigated. The research results showed that the proposed material in its physical and mechanical properties meets the requirements for the material of outer walls. The material has been found to be highly corrosion resistant. Previously, the author presented the results of research of thermal conductivity of LPSC for exterior walls in laboratory conditions. The results of study of temperature and humidity conditions of the wall fragment of the proposed material in natural conditions are given in this article. The studies carried out confirmed the possibility of using the material proposed by the author for the outer walls of buildings with acidic humid-gas production environments.

Automated technique for high-pressure water-based window cleaning and accompanying parametric study.

The maintenance of buildings has become an important issue with the construction of many high-rise buildings in recent years. However, the cleaning of the outer walls of buildings is performed in highly hazardous environments over long periods, and many accidents occur each year. Various robots are being studied and developed to reduce these incidents and to relieve workers from hazardous tasks. Herein, we propose a method of spraying high-pressure water using a pump and nozzle, which differs from conventional methods. The cleaning performance parameters, such as water pressure, spray angle, and spray distance, were optimized using the Taguchi method. Cleaning experiments were performed on window specimens that were contaminated artificially. The cleaning performance of the proposed method was evaluated using the image-evaluation method. The optimum condition was determined based on the results of a sensitive analysis performed on the image data. In addition, the reaction force due to high pressure and impact force on the specimens were investigated. These forces were not sufficient to affect the propeller thrust or cause damage to the building's surface. We expect to perform field tests in the near future based on the output of this research.

Design of Window-Cleaning Robotic Manipulator With Compliant Adaptation Capability

The number of high-rise buildings is increasing worldwide, and the demand for window maintenance and cleaning has increased accordingly. However, there is an increased desire to substitute robots with human workers because of the occurrence of many accidents. Although many window-cleaning robots have been developed, almost all the robots cannot passively pass obstacles on the outer walls of buildings. In this article, a window-cleaning robot is provided with compliant adaptation capabilities by adding series elastic actuators and tristar wheels to an older window-cleaning robot. This robot has a two-degree-of-freedom manipulator, and the robot can passively overcome obstacles without any need for control. An optimization is performed for the manipulator, and the experiments are performed with the manipulator to compare the respective abilities to overcome the obstacles using parameters before and after the optimization. In addition, a cleaning module is constructed by scaling down the previous model. The performance of the downscaled cleaning module is validated using a window-cleaning experiment.

Investigating the influence of different speeds and directions of winds on the performance of split air conditioning systems

Air-cooled condensers are generally preferred in the condensing units of split air conditioning systems because of simple construction, lower operating costs, and water scarcity in many regions. This work presents a numerical analysis of the influence of winds at different speeds and directions on the performance of a split air conditioning system whose condensing unit is installed on the outer walls of buildings using mounting brackets. Commercially available simulation tools are used in this work to obtain airflow and thermal characteristics of the condensing unit as well as the performance of the air conditioning system. The simulation tools are validated at the original design point for correct and reliable simulation results. It is found that the temperature of air entering the condensing unit raises due to recirculation of the hot exhaust air caused by winds. The airflow rates in the condensing unit are reduced. This leads to an inefficient operation of the air conditioning system.

Thermo-flow performance analysis of split air conditioner under high-speed winds around buildings

ABSTRACT Air-cooled condensers are predominantly used in condensing units of split air conditioning systems. These units are mostly installed on terraces or on outer walls of buildings. In case of tall buildings, the performance of air-cooled condenser is greatly affected by high-speed winds. Present work deals with a numerical study predicting the influence of high-speed winds on the performance of split air conditioning systems whose condensing units are installed on outer walls of buildings using mounting brackets. Simulation tools viz. ANSYS Fluent and VapCyc are employed in this work in order to obtain air flow and thermal characteristics of the condensing unit. Simulation results show that the thermo-flow performance of the split air conditioning system deteriorates significantly with high-speed winds due to an increase in the temperature of air entering the condensing unit and inferior air flow rates in the condensing unit. It is observed that the cooling capacity and coefficient of performance of the air conditioning system are reduced by 11% and 35%, respectively, when wind speed is 12.3 m/s in comparison with the baseline case.

Application of monolithic foam concrete in building envelopes of a cottage, used in conditions of intermittent heating

The paper focuses upon the peculiarities of application of monolithic foam concrete as a heat-insulating layer in building envelopes of houses used in conditions of intermittent heating. The researchers analyze thermal characteristics, review literature describing the application of foam concrete in construction and demonstrate this material applicability at outer walls insulating, taking buildings and constructions with variable thermal behaviour as an example. The paper outlines main criteria that building envelopes of such structures should meet. To assess the effectiveness of monolithic foam concrete in building envelopes application, the authors carried out thermo-technical calculation of the outer walls, insulated with monolithic foam concrete. The graphs of dependence of multilayer building envelope heating time upon thickness of a heat-insulating layer and upon heat transmission resistance of the construction was obtained on the basis of these calculations. The dependence of specific energy consumption upon the heating time is also given in the paper. The study reveals the optimal range of thickness and density of monolithic foam concrete for insulating outer walls of buildings, used in in conditions of intermittent heating. This calculation also proves that the application of foam concrete as an insulant on the inside of the outer wall makes it possible to reduce the load on the building foundation.

EFFECTS OF SOCIAL FACTORS ON A DESIRED LEVEL OF THERMAL PROTECTION OF OUTER WALLS OF RESIDENTIAL BUILDINGS

The requirements to a desired level of thermal protection of outer walls of buildings have been analysed. The relation between such requirements and social factors of a country was shown. Comparison data regarding heat releasing surface area of outer walls and windows and heat losses per person have been received for variable residential density of apartments. The authors have shown international practices and the needs for transition to construction of buildings with a higher level of thermal protection of outer walls. Since cold generation is 3-5 times as expensive as heat generation for many buildings, the transition was made from ventilation of the naturally driven type to controlled and mechanical one providing heat recovery of exhaust air. It was suggested that problem of energy-saving in the sector of construction and housing and communal services could be solved providing a desired life of outer walls and costs of current and major repairs required for projected lifetime of a building.

Vertical Corner Feature Based Precise Vehicle Localization Using 3D LIDAR in Urban Area.

Tall buildings are concentrated in urban areas. The outer walls of buildings are vertically erected to the ground and almost flat. Therefore, the vertical corners that meet the vertical planes are present everywhere in urban areas. These corners act as convenient landmarks, which can be extracted by using the light detection and ranging (LIDAR) sensor. A vertical corner feature based precise vehicle localization method is proposed in this paper and implemented using 3D LIDAR (Velodyne HDL-32E). The vehicle motion is predicted by accumulating the pose increment output from the iterative closest point (ICP) algorithm based on the geometric relations between the scan data of the 3D LIDAR. The vertical corner is extracted using the proposed corner extraction method. The vehicle position is then corrected by matching the prebuilt corner map with the extracted corner. The experiment was carried out in the Gangnam area of Seoul, South Korea. In the experimental results, the maximum horizontal position error is about 0.46 m and the 2D Root Mean Square (RMS) horizontal error is about 0.138 m.

Thermal Design on Cement-Based Vitrified Microsphere Insulation Mortar Based on 65% Building Energy Efficiency Standard

With the 65% building energy efficiency standards being implemented, the existing external wall insulation technology will face severe challenges. The research and application of the high performance inorganic insulation materials are solicited, because the traditional organic insulation materials representative with polystyrene have some defects, such as poor fire resistance, poor durability, short service and no synchronous with the life of structure, and environmental pollution. After the big fires of the CCTV building in 2009 and the building under construction at Shanghai pudong south road NO.1 in 2010, October 8 in the morning being occurred, the new generation inorganic insulation materials represented by vitrified microsphere, are getting increasing attention. After the thermal simulation of external walls, roof, floor and windows being calculated, it is concluded that its energy-saving rate is far more than energy efficiency 50% standard, and which is close to energy efficiency 65% standard, even if taking only vitrified microsphere as the insulation mortar for outer walls of building.

A STUDY ON THE INVESTIGATION FOR CHOOSING THE CRACK REPAIR METHOD BASED ON ACTUAL MOVEMENTS OF CRACKS OCCURRED IN THE BUILDING WALLS

This research aims at rationalization of the selecting technique of a crack repair method of construction with the movement occurred in RC structure. The definition of“existence of crack width behavior”of the flow chart in the public organization's specifications for crack repair method selection is so ambiguous. In this research, behavior of the crack produced in the outer wall of an actual building was measured, and new knowledge was able to be acquired about the opening-and-closing pattern and crack width behavior of cracks which were produced in the outer wall of building. Although it was generated in the building of only one building, and the cracks and consideration in this paper are based on this measurement results, it was thought that the results of this paper has the flexibility about the crack investigation for selection of a repair method of construction.

TECHNICAL AND MANAGERIAL CHALLENGES OF FACADE RETENTION.

When the outer walls of buildings are retained while the main building is demolished and replaced by a new structural frame, a retained facade results. The challenges created by this method of construction are unique and this paper focuses on the technical and managerial issues relating to this approach. It identifies options for developing existing buildings ; reasons for employing retained facades; and important technical considerations which need to be addressed by designers and contractors, including temporary support, connection between facades and new structures, strengthening a facade's existing foundations and design of new foundations for these facades. Some of the major management implications of retained facades are also described. These include contractual issues, surveys, inspections and monitoring of facades, access and safety, programming and statutory control. The paper is based on case studies of contemporary construction projects, surveys of construction engineers and managers, and relevant literature.

BİNANIN ENERJİ SƏMƏRƏLİYİNƏ TƏSİR EDƏN XARİCİ KONSTRUKSIYALARIN NORMALAŞDIRILMIŞ İSTİLIK- TEXNİKİ PARAMETRLƏRİ

Abstract. Energy losses occurring in the building envelope structures mainly depend on the thermal and technical indicators of the used construction materials, the operating conditions of the building, optimal structural-architectural-design solutions and climatic indicators of the construction region. At the moment, the outer walls of buildings in Baku with a thickness of 0.2-0.4 m from limestone or hollow bricks does not meet the energy efficiency requirement according to the valid construction norms. In the article, from the point of view of solving the problems of thermal protection of buildings, an analysis of the requirements imposed on external structures for the optimal design of construction structures was carried out. The thickness of the outer wall made of limestone should not be less than 1.34 m, hollow brick 0.97 m, and porous concrete (Gobustone) 0.28 m. It is not realistic to build an external wall of the specified thickness from limestone and hollow bricks. In order to meet the energy efficiency requirements of modern buildings, a thermal insulation layer must be used in this type of external wall constructions. Keywords: actual