Table of contents

4^th - 5^th November 2021, Braşov, Romania

Selected, peer reviewed papers from the International Conference Civil Engineering and Building Services CIBv2021

Edited by:

Ioan TUNS

Transilvania University of Brasov, Romania

Radu MUNTEAN

Transilvania University of Brasov, Romania

Dorin RADU

Transilvania University of Brasov, Romania

Teofil-Florin GĂLĂţANU

Transilvania University of Brasov, Romania

Christiana Emilia CAZACU

Transilvania University of Brasov, Romania

FOREWORD

The International Scientific Conference CIBv represents one of the most important and traditionally scientific events of Civil Engineering and Building Services in Romania, enjoying increasingly higher visibility at the international level.

The aim of the CIBv conference is to provide a platform for researchers, engineers, academicians as well as professionals from all over the world to present their research results and development activities. It also provides opportunities for the participants to exchange new ideas and application experiences, to establish business or research relations and to find other partners and even friends for future collaboration.

List of International Conference CIBv2021 Civil Engineering and Building Services Faculty of Civil Engineering, Transilvania University of Brasov, Romania in collaboration with Shenyang Jianzhu University, China, Honorary Committee, International academic scientific committee, Organizing committee these are available in this pdf.

All papers published in this volume have been reviewed through processes administered by the Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

• Type of peer review: Single Anonymous

• Conference submission management system: The submission management was an on website uploading type one. Each abstract was uploaded on the conference website and the papers were sent directly via conference e-mail.

• Number of submissions received: 65

• Number of submissions sent for review: 51

• Number of submissions accepted: 47

• Acceptance Rate (Submissions Accepted / Submissions Received × 100): 72.3

• Average number of reviews per paper: 2

• Total number of reviewers involved: 48

• Contact person for queries:

Name: Dorin Radu

Email: dorin.radu@unitbv.ro

Affiliation: Transilvania University of Brasov

The objectives of the research were to analyse how the treatment with sodium hydroxide solution of hemp stems influences the mechanical and thermal behaviours of concrete when hemp stems are used in the composition of concrete. Tests were performed on hemp concrete samples to evaluate the density and measure the heat transfer coefficient, compressive strength and modulus of elasticity. The activities carried out aimed to identify the influence of the sodium hydroxide solution concentration on the variations of the measured parameters and expressing some conclusions regarding the need to treat the hemp stems before their use in concrete. The need for research is given by the nowadays demand for obtaining eco-sustainable construction materials, in which the possibility of using a material that is considered plant waste becomes an economic resource in a circular economy.

Reducing the energy consumption needed for creating suitable indoor conditions has become a significant issue on a global scale. The building's envelope and service systems have the most important influence over the amount of energy consumed. This aspect is related to reducing the heat flux across the building envelope in summer conditions and preventing the condensation and infiltration risk in the winter period. The research regarding ventilated façades has advanced taking into account these advantages, which emphasized the need to study and create constructive solutions adapted to the conditions. In this context, this paper represents a brief introduction to ventilated façades solutions, taking into account the definition, their characteristics, the principal constructive elements, the main types of ventilated facades, and last, but not least, their advantages and disadvantages. The authors believe that the study is critical in fully comprehending the characteristics of these systems and their primary components, as well as designing and implementing them in accordance with current environmental needs. It is anticipated that comprehending this concept, as well as its evolution and trends, can contribute in the resolving of a number of ecological and societal issues.

This article analyzes the structures of some antioxidants, UV stabilizers, and inhibitors utilized to improve the polymeric materials' functionalities using Cheminformatics tools implemented in the R software. Based on their properties, the dendrograms are drawn, and the molecules are classified in clusters, utilizing hierarchical clustering and the k-means algorithm.

Nowadays, climate change is one of the most important threads for civilization. Having the origin mainly in the anthropic activity and intensive use of the environmental resources, climate change affects the ecosystems and the population lives. Changes in precipitation volume and cycles severely affect agriculture and food security. Therefore, building meteorological forecasting is important for planning agricultural works and water management. In this respect, this article attempts to create an image of the future precipitation evolution in the northern part of Dobrogea, a region more and more affected by extreme meteorological events - long drought periods, followed by high precipitation amounts.

The location of the new radar station facility is located at the top of the Besna Kobila mountain in Serbia at an altitude of approximately 1904 m. The construction of the building is reinforced concrete. The building consists of ground floor and first floor with technical and other areas. From the 2nd to the 6th floor there is a communication central reinforced concrete core. At the level of the 6th floor, a platform was formed for storing equipment and supporting the antenna dome with a diameter of R = 15. The total height of the building with a dome is H = 37.0 m. Horizontal floor structures are in the form of reinforced concrete slabs supported on reinforced concrete walls 20 (30) cm thick, columns of different dimensions, and a system of reinforced concrete beams of different cross section. The vertical construction consists of load-bearing reinforced concrete columns, external and internal concrete walls. In the central part of the building, there is a staircase in the form of reinforced concrete slabs with a thickness of d = 16 cm, as well as reinforced concrete elevator core with a square base of approximately 560.0 cm. The calculation of the structure is performed for loads from its own weight, constant loads from the materialization of the object, loads from the equipment and for payloads: from snow and wind and seismic loads of intensity IX. The basic load of the dome is the wind according to the average speed of 70.0 m / sec (according to the measured data). The foundation of the building is on a reinforced concrete slab and reinforcements-capitals under the columns.

In the process of engineering survey of the operated reinforced concrete structures of buildings and erections, various methods are being used. According to their approach, they are divided into two groups: destructive and non-destructive testing methods. The main disadvantage of destructive testing methods is the violation of the "testing integrity", i.e. only the part of a structure is used in tests. When selecting core samples, for example, concrete cores from the "body" of a structure, a new, essentially independent, structural element is formed. In other words, the behavior of a sample that is the part of a reinforced concrete structure may differ from the behavior of the same part in the structure as a whole during experimental testing. The noted shortcomings can affect the accuracy of the research results, which means that the answers to the questions posed before the technical inspection of a facility cannot be adequate. Methods of reinforced concrete structures' inspection that partially or completely solve the problems of destructive testing are non-destructive methods. The paper concerns the system analysis of up-to-date methods of non-destructive testing of main performance properties of reinforced concrete structures.

Knowing people's needs for a healthy life is a fundamental theme for those who design and execute constructions. The environment of a building must combine the most important factors for comfort and health. For a new construction, the hygiene and health of the occupants must become a priority strategy, and needs to be considered early on in the project because it is key to securing a safe construction. How do constructions make us sick and what are the main causes and phenomena, and what consequences do they have on our health are the principal subject from this study. The designer must use materials that are thermally efficient, healthy and comfortable that provides better constructions for the occupants.

The lack of a good foundation ground layer in some areas that could be used for construction proposes is a common problem all over the world. Today, more and more researches are focused on finding new solutions to improve the soil parameters in order to obtain a stabilized foundation layer. Finding an optimal admixture between the local soils, needed for construction purposes, hydraulic binders and the precise amount of water, may be the future of a revolutionary discovery in this field. The experimental study based on the admixture of a sandy silty clay with hydraulic binders from the Viacalco© [1] range, produced by Carmeuse Romania, in a percentage of 2%, 4% and 6% led to a significant improvement of the geotechnical parameters of the soil. The aim of this experimental study is to determine the optimal binder mixture in order to improve local soils and to obtain low investment costs.

The paper studies the behavior of a medium height masonry walls building, placed in Satu Mare (Romania). It contains large balcony consoles and a large hall at the top story, covered by a timber roof. The roof trusses sit at both ends on the external walls. The study's purpose is to determine the importance of large slab consoles and walls buttresses at the top story, for the structure. The paper compares the structure's behavior in 3 cases. The first contains both large consoles and wall spurs, the second only incorporates pier buttresses and the third holds just the balcony consoles. The structure's behavior for both the elastic and plastic stage is compared for the 3 cases. The plastic stage shows the bending moment's distribution in slabs and stresses in masonry walls during stages when they surpass the masonry strengths. The plastic hinges development at structure collapse and the pushover diagrams for each case along with the results interpretation are presented. A nonlinear analysis is done for the timber roof also, for both orthogonal directions. The study shows both large consoles and halls at the top floor are appropriate for masonry structures, if designed correctly.

Nowadays, due to architectural necessities, structures have emerged in many different plane shapes, such as U, V, L T and others. It is important to establish if a nonrectangular shape causes important changes both for the bearing and non-bearing elements, compared to a rectangular one. The paper shows the impact a buildings shapes on the partitioning walls. For this paper the structures in study are two high rise reinforced concrete walls buildings placed in a high seismic area (Bucharest, Romania). The partitioning walls are made of masonry. Both bearing and non-bearing walls are the same for both buildings. They are just placed in different locations, so that the structures have different shapes in plan. One has the shape of an I and the other of a V. The paper studies the buildings behavior in both cases. The masonry walls stresses are analysed for both the elastic and plastic stage. The conclusion is that in this case, for these shapes, the non-bearing walls are not affected very much by the building's plane shape.

Assessing the vulnerability of buildings is very important to determine the settlements affected by floods since authorities can take measures before actual flooding takes place. The present research aims to identify areas affected by flooding in Cernăteşti. The village is located in an area where floods are favored by the elongated shape of the catchment, the horizontal slope, relatively small distance between the hills bordering the valley, water accumulation resulting from flash floods formed upstream, and heavy local rainfall. Field observations, GIS techniques, and mathematical calculations have been used in this research. Flood simulations have been made to determine the degree (number of houses and roads affected, estimated losses in lei) of impact at flows with different probabilities of exceedance (10%, 5%, 2%, and 1%). Depending on the exposure, calculated using factors like distance from the river or construction material, the buildings on the left bank of Slănic are more affected and the flooded area is more extensive. Buildings in the south-eastern, north-eastern, and north-western parts of the flooded area are highly vulnerable, but most of the other settlements are less vulnerable.

The basic concern on the fire compartmentation is focused on to limit the spread of the fire and smoke outside of the room of the fire origin. Where the fire compartmentation is required, the elements forming the boundaries of the fire compartment should be designed and constructed in such a way that they maintain their separating function during the relevant fire exposure [1]. The general accepted method for assessing the fire resistance of a structural or non-structural member is the full-scale testing of the fire performance, however, several calculation methods for verification of the separation function of timber assemblies can also be used in order to prove compliance with the code regulations [2].

This article is an overview about alternative solutions for reinforced concrete by using different types of fibers. The use of fiber reinforced concrete when is compared to the conventional reinforced concrete solutions. This study has taken in consideration structural performance and the total cost. The use of fibers or dispersed reinforcement also improves some of the characteristics of concrete, such as those related to: cracking, freezing, durability, erosion of ordinary or marine water, wind erosion, permeability, etc. In order to correct to a large extent, the unfavorable characteristics of the reinforced concrete, in the mass of the fresh concrete various types of fibers can be mixed and incorporated in the use of concrete with dispersed reinforcement. As materials often used as fibers, the most commonly are: hooked-end steel (steel fibers), straight polypropylene and straight polyolefin, glass fiber, carbon fiber, aramid fiber, natural hemp fibers, jute, hair, straw, etc.

Compared to traditional composite steel-concrete beams, where the concrete slab is supported by the top flange of a steel profile, in slim floor systems, the beam is integrated into the height of the concrete slab. These configurations are popular due to their cost-effectiveness and fire performance. However, fire design requires advanced calculation models, as Eurocodes do not provide a simplified method for the analysis of these types of beams when exposed to fire. The validation of the numerical models is an important issue for researchers, designers, software developers, and authorities. The European Standard for the fire design of composite steel and concrete structures, EN 1994-1-2, states that advanced calculation models must be validated against experimental test results. The paper presents the validation of a numerical model, for the thermal and mechanical analysis of slim floor beams, using SAFIR software. SAFIR is a special purpose computer program, based on the Finite Element Method, developed for the analysis of structures under elevated temperature conditions. The model is validated against an existing experimental fire test, available in the literature. The temperatures on the cross-section and the vertical beam displacements obtained numerically are reproducing very well the experimental results.

Stone materials are widely used in interior and exterior decoration design and public facilities construction. They are one of the essential materials in the construction and decoration field. With the increase in demand of the personality and quality of the decoration materials, intelligent manufacturing of stone processing must be required. With the development of manufacturing technology, especially the rapid development of automatic control technology, CNC machining technology and industrial robot technology, flexible manufacturing technology (FMI) have been used. In the paper an intelligent flexible processing system of stone is designed, which is composed with CNC processing tool, material transmission and storage system, computer control system and stone processing process monitoring system. It can realize fully automatic and intelligent flexible production from building stone processing, stone handling, comprehensive waste treatment, tool optimization and computer control. The calculation method of optimal equipment layout is explained and the field layout of each unit of FMS is given. The purpose of this project is to improve the intelligent level of building decoration stone processing through flexible manufacturing technology and increase production efficiency and material utilization as well as to satisfy needs of diversified product.

In recent years, due to the development of UAV (Unmanned aerial vehicle) technology, UAVs have been used in an increasingly wide range of applications, including the architecture industry. In the field of architecture, the technologies of capturing images of building conditions with UAVs have a huge development, such as architectural planning, remote terrain detection, construction safety supervision and so forth. In general, the applications can be expanded widly, owing to the convenient operation of UAVs for the flyers and that does not require a high degree of precision for the control. However, when it comes to penetration between and within buildings. The lack of flight vision and signal interference often leads to collisions and crashes. Hence, this paper studies how to further optimise the control accuracy of construction measurement UAVs. The aim is to reduce the difficulty of operating the UAV when it faces to interference during architecture measurement. In this paper, a three DOFs two-rotor UAV is selected as the object of study. A mathematical model of the UAV is constructed, which is followed by the designing of an advanced controller based on a PID controller and an MPC (model predictive controller) controller, used for realising offset free reference tracking when changing elevation, pitch and travel angles. The usage of this controller can significantly reduce the cost of control during flight to reduce control bias in the presence of disturbing factors. The application of the controller to UAVs allows for automated and intelligent UAV control.

In order to study the flexural behavior of graphene oxide (GO) recycled concrete beams, 6 GO recycled concrete beams were studied, and observe its failure mode and process. The effects of GO content, oxygen content of GO and replacement rate of recycled aggregate on the flexural behavior of the test beams, including cracking load and ultimate load, concrete strain and steel strain, mid-span deflection, were analyzed. The test results show that the cracking load and ultimate load of recycled concrete beams with GO increase to a certain extent with the increase of GO content. And the higher the oxygen content of GO, the higher the ultimate bearing capacity of GO recycled concrete beams. With the increase of replacement rate of recycled aggregate, the cracking load and ultimate load of the test beams decrease.

Hollow section steel profiles are widely used for industrial purpose. Next to circular hollow section, which are set to for example offshore constructions, squared hollow section profiles have many advantages. The profiles are lightweight, have got a high rotational stiffness and in contrast to circular profiles, squared profiles can be welded more easily without having multiplanar welding radii. The weakest point of columns with two or more members is the node. Due to the geometrical heterogeneity and the imperfection due to the process of welding it is a complex part to calculate.

This paper is about a numerical case study of a full-overlapped squared hollow section joint. A focus is the influence of the inclination angle on the maximum stresses and deflection in the ultimate limit state. The analysis is split into symmetrical and asymmetrical structures. The aim is to figure out the influence of the inclination angle on the stability of the joint.

The aim of this article is to analyse multiple solutions for the stone cantilevers rehabilitation commonly found in heritage buildings. The stone cantilevers are arranged in the inner courtyards of historical buildings and ensure horizontal circulation. Throughout the article will analyse two categories of situations encountered in the rehabilitation practice: for the first situation the cantilever rehabilitation can be done after the stone plate demolition, and for the second situation the cantilever rehabilitation must be done without having the option of demolishing the flat plates. The difficulty of the intervention is given by the fact that the fixed ending restrain of the cantilever was ensured during the execution technology, the cantilever fixed in the masonry being ensured during the building of the wall. The rehabilitation of the stone cantilevers is conditioned by the fact that the fixed ending restrain point cannot be rebuild on the initial principles. This fact requires the adoption of rehabilitation principles based on a different approach to ensure the fixed end point. The proposed solutions solve both issues ensuring the required load capacity of the cantilever and ensuring the required level of fixed end restrain

With the continuous improvement for the safety of stone installation, the quality detection of its machined surface is also improving. But its surface crack was always a difficult problem in detection. In recent years, with the rapid development of image processing technology a new method to solve this problem can be realized. In this paper, CCD camera was used to detect the surface crack and roughness of stone slabs. The research about image correction and image enhancement was carried, so as to eliminate noise and protect the crack edge in the greatest extent. The improved threshold segmentation algorithm was used to segment image of linear fracture filtering. Mathematical morphology was applied to refinement of single pixel of crack in order to gain crack size. The CCD camera and micro lens are assembled as image sensors to enlarge the surface of stone and take a sample by many taking pictures. The surface profile of the tested stone slab is obtained by reconstruction method, and the surface roughness of stone slab is finally obtained by analysis and calculation. Through this research, a fast detection technology was realized, which solves the problems of low processing efficiency and high cost in production. The result shows certain theoretical value and practical application significance.

It is widely established that the building industry has a negative impact on the environment and a significant influence on the phenomena that contribute to climate change. Traditional construction materials, such as cement, contribute considerably to environmental pollution. Given the enormous quantity of energy and materials used by the construction sector, this industry must adopt more sustainable practices. Nowadays, an increasing number of natural building materials are used in the structural component or the insulation of buildings. As a result, natural construction materials may be a superior alternative to accomplish this goal. This article discusses the features and applications of hempcrete in the building industry. Hempcrete is a sustainable material composed of industrial hemp, lime as a binder, and water. Due to hemp's porous structure, it has deformation capacity, sound-absorbing qualities, better hygrothermal properties than conventional concrete, and, depending on the proportions of hemp, lime, and water, fire resistant capabilities due to the presence of lime.

In the last years, research applications in the construction sector have taken a different turn due to rapid urbanization and the necessity to protect the environment and create a balance between the natural and built environments. Taking into account the fact that the thermal efficiency of buildings has an important influence over the environmental performances of the construction sector, the civil engineering specialists have tried to develop and use different new solutions in order to improve this essential building characteristic. Thus, different new materials have been used with the goal of reducing the overall thermal transmittance of the envelope elements and of the total energy consumption needed for heating and cooling. Perlite is one of the materials that have been considered for developing new energy efficient construction applications. The main goal of the present paper is to present all the relevant solutions that have been developed and used in the construction sector that consider perlite as a component part. The present study is the first part of a more extensive research program that takes under evaluation the possibility of using perlite as a thermal insulating material for different constructions.

The paper presents a case study performed on a site for residential buildings, arranged by terracing on a sloping ground. The built site, subject to investigations, shows an obvious state of degradation downstream, manifested by the development of concentric cracks, penetrated deep, as a result of displacements/rotations produced in the massif of soil susceptible to sliding. The analyzed comparative solutions aim at achieving mechanical barriers developed in dep, taking the tensile efforts through reinforced soil works and improving the shear resistance of the soil.

The study presents the data obtained on a large span structure equipped with passive seismic isolators, placed at roof level, when subjected to multiple seismic loads. Three distinct passive isolation systems are taken into consideration to reduce the seismic response of the structure. The first case uses Friction Pendulum Systems (FP), the second uses a combination of High Damping Rubber Bearing (HDRB) and low friction pot-bearing systems, and the third implies the use of Lead Rubber Bearings (LRB) and low friction pot-bearing systems. Using seven sets of accelerograms, recorded and generated, the values for the main seismic response parameters are extracted in to underline the efficiency of the proposed systems. The results obtained in terms of natural vibration period, accelerations, bending moment, base shear are compared.

In the field of non-destructive investigations, the arrival time of the elastic waves is the important parameters to visualize the locations of the failures and/or elastic wave velocity distributions that are generally used for the soundness evaluation. The accuracy of the visualization depends on the accuracy of the arrival times, and it is demanded that the arrival times are detected automatically with required accuracy from huge amount of the elastic wave measurement data for the practical applications. In this paper, a method of the arrival time detection is proposed on the basis of the sparse matrix computation. The root mean square voltages in the noise of the wave form, is used as an index to separate the elastic waves between the noise and the signal, and the boundary of the index between the noise and the signal in the wave forms is determined in the sparse matrix. Therefore, the arrival times located in the boundary of the noise and it is detected by sparse matrix computations. The proposed method is verified on the model tests and compared with the conventional method, and it was confirmed that the proposed method detects more arrival time accurately in comparison with the conventional method.

The main idea of this project was to create an access road for the tourists and also to improve the winter sports conditions, especially the ski, in the beautiful Parag Mountains. It was a very challenging project, as the road takes until 1600 m at alpine elevation. One of the structures was delivered and assembled in November 2019, in 3 weeks of hard weather conditions, with a 5 working men team.

The study was conducted in the Laboratories of the Faculty of Civil engineering and Building Services, department of Concrete, Materials, Technology and Management, Technical University "Gheorghe Asachi" from Iassy. The main objective of the experimental research from this paper is the analysis of some types of concretes prepared with polystyrene granules and fly ash, aiming to obtain a material which is corresponding to the structural requirements, to be energetically efficient and to be ecological. Using these components, the durability characteristics (frost - thaw and corrosion), the influence of the polystyrene granules on the environment and the mode in which the materials properties are maintained in time under environmental factors, were experimentally determined. The concretes were prepared with polystyrene granules and fly ash from CET Holboca Iassy, Romania. The fly ash was utilized in proportion of 10% and 20% from the cement amount and the polystyrene granules replaced some sorts of the natural aggregate. The types of concretes are CPOL1, CPOL2, CPOL3 and CPOL4.

The effort to reduce the consumption generated by the use of buildings is one of the important objectives of today's global society, involving authorities that regulate the energy performance of buildings, manufacturers of materials, specialists involved in the design and last but not least the occupants of buildings. The habits of the occupants of buildings regarding the indoor comfort temperature have a direct influence on the amount of energy consumed. The paper aims to highlight whether the results expected by applying the values recommended in the regulations are in line with the occupant's habits. Based on a case study, the energy requirement for heating was assessed using different indoor temperatures, which were established in relation to the temperatures monitored in situ. The inside temperature values were monitored in three buildings, located in the third climatic zone of Romania. The article presents the results of the case study, emphasizing that indoor temperature control and monitoring are of high importance in the desired expectations for energy performance of buildings, to meet the sustainability objectives. Knowing the mutual influence between energy consumption and thermal comfort demands, building designers can find solutions to achieve energy conservation goals.

In the process of human resource system test design in construction enterprises, various test design methods are often used, such as equivalence class division, boundary value analysis, causal graph, error inference and so on. How to choose the correct test design method is related to the rationality of test case design and high efficiency of test execution. Therefore, the selection of appropriate test design method plays a vital role in use case design. In this paper, the basic use of equivalence class partition and boundary value analysis and their relationship are briefly described. It is hoped that it can be used for reference in the study of human resource system test cases in construction enterprises.

This article presents a calculation algorithm for establishing the electricity demand consumed by the railway electric traction system on a railway section, as well as methods for lowering power consumption and cost. In order to conceive the calculation algorithm, the following variables are taken into account: the number of trains in circulation on the section, the slope of the section, the train speed and the speed restrictions. For factors that substantially increase electricity consumption, but can be controlled, optimal values are computed using specific equations in the MATLAB program. The optimal values are implemented using the train's timetable or a railway control system (SCADA). A decrease in power consumption of 5% can be expected with this method.

In order to further improve the running speed and stability of the feed truck in the mud production line, optimization simulation and experimental research on the running system of the feed truck were carried out. First, based on the analysis of the operating system of the material truck, Then, according to the experimental plan, an optimization experiment on the project site was carried out, and it was confirmed in a quantitative form that the operating efficiency and stability of the optimized truck operating system have been significantly improved. Finally, the experimental results are applied and analyzed, and a mathematical model that can be used in actual engineering is obtained, so as to reflect the actual engineering application value.

This paper verifies the compressive sampling(CS)-based elastic wave velocity tomography(EWT) technique. Conventional elastic wave velocity tomography necessitates the quantity of effort and time. Nevertheless, because the central premise of CS algorithm is to recover the original velocity distribution from random measurement subsampling, compressive sampling is adopted at overcoming this challenge. CS algorithm chose fewer paths from entire measurements during the measurement stage. After that, the L1-minimization optimization method adopts to recover the damage area and magnitude in the visualization stage. Because of hugely reduces the measurement workload and a high level of accuracy reconstruction, CS algorithm is more effective in comparison with the conventional algorithms of elastic wave velocity tomography.

The topic of sustainability is of utmost importance today, especially referring to construction industry - a sector that contributes with almost 40% to the global CO2 emissions. This subject comprises various areas of research and knowledge and one study cannot cover all of them; the studies are usually focusing on a restrained field starting from one of the sustainability characteristics. Some principles of sustainable development are referring to the use of natural products, using local raw materials, using traditional construction methods, and respecting the cultural heritage. Therefore, in this context, the use of natural stone could be a sustainable solution especially in communities that historically used stone as a building material. Considering the value which the use of natural stone in new and existing buildings could bring for a more sustainable society, the current study aims to explore how topics like use of natural stone, stone processing, stone restauration and others related to them are included in the educational programs and curricula of higher education and vocational education and training in Romania. The results are compared with the situation from other European countries in order to formulate some conclusions and recommendations.

This research started from the fact that humanity exploits on an industrial scale and chaotically consumes the raw materials that this planet offers, without realizing the importance of reusing waste and the possibility of introducing them in the production of plaster mortars. Thus, an attempt is made to create a balance between raw materials and the exploitation of new resources, so that future generations can have access to raw materials. Plaster mortar mixtures were made by using waste from construction sites, respectively certain percentages of the amount of cement were replaced with used paints. In order to reduce the costs of transporting and transferring waste to the landfill, most of the executors (builders) at the stage of systematization of the land, bury all the waste, not respecting the conditions given by the environmental agreement. Through a waste management, construction materials are recovered, in this case used paint and reused in the preparation of plaster mortar. Starting from a plaster mortar mixture, the cement was replaced in a percentage of 10% and 15% with used paint, resulting in significantly higher bending strengths. We must be responsible and contribute to the protection of the environment by recycling/reusing waste from construction materials.

"Braila Emergency County Hospital (ECH)" historical monument represents one of the main objectives of structural rehabilitation in both Braila county and Braila city. Thus, a structural strength verification for Pavilion B, Section 2, using ETABS software was performed, in order to find optimal retrofitting (rehabilitation) solutions. This analytical procedure proved to be beneficial and absolutely necessary, due to observations regarding the spatial contribution of masonry shear walls and finally the proper establishment of capable/design efforts. Following the structural calculation, it was concluded that the best solution would be to use composite materials for retrofitting a certain number of masonry shear walls, as classical retrofitting methods proved to be more expensive and structurally inefficient. Furthermore, in the context of the COVID-19 pandemic, the solution to use composite materials is beneficial, as it would entail no personnel or patients to be evacuated during the rehabilitation works, i.e. the hospital being able to continue to operate.

The rotor is the key component of the rotary drilling rig, it can realize the rotation and feed movement of the drill. the rotor unit of the rotary drilling rig should take on-line dynamic. Because unbalanced faults would lead to vibration. In order to further improve the pricision of on-line dynamic balance, an optimization strategy based on Genetic Algorithm for the mass compensation of the rotor on-line dynamic balancing system is proposed. A mass compensation optimization model is established. By the way of taking the phase of counterweight movement as the optimization variable. At the same time,taking the residual stress under dynamic balance as the optimization objective. According to the principle of Genetic Algorithm, the movement phase of the counterweight can be calculated when the residual force reaches the minimum value. By performing simulation analysis, the residual force can be calculated under different rotating speeds and different amount of unbalance, the residual force after optimizing balance can be reduced greatly. The simulation results showed that the residual force of the rotor after optimizing balance can decrease by 95.74% on average. Therefore, an optimization strategy based on Genetic Algorithm for the mass compensation of the rotor can effectively improve dynamic balance precision and operating performance of rotary drilling rig.

This study addresses the need to improve life on earth by finding a way to reintroduce ubiquitous waste back into the system. On a hand, there is the amount of cellulosic waste that can no longer be reintroduced into the paper recycling process. On the other hand, the amount of cement used globally, is growing alarmingly. My study seeks the balance of a mix of these two materials, which would generate desirable effects both from an engineering and ecological point of view. Paper ash, is a material made of particles of various sizes and can play various roles in the composition of mortars. The efficacy of particles up to 0.025 mm in size (powder ash) as a cement substitute and the efficiency of particles in size between 0.025 and 8 mm (flakes) as a pozzolanic additive are demonstrated. The results of the mechanical tests to which the samples were subjected show the possibility of reducing the amount of cement used in standard recipes by adding ash from recycled paper, without compromising the physical and mechanical properties of the mortars. The cement economy can rise up to 20 percent while the mechanical strength increases by 5-10 percent compared to the basic recipe.

As the country's underground tunnels continue to expand, underground construction technology has been developed rapidly. In order to meet the development needs of construction technology in China, Tunnel Boring Machine (TBM) has made great progress due to its own advantages. In this paper, feed amount of disc cutter on rock crushing under complex working conditions is considered. The mechanism of rock fragmentation is analyzed. The force between disc cutter and the rock is studied. The accuracy of the model is verified by setting up a TBM rock fragmentation experiment platform. This study provides technical support for TBM construction parameters under different working conditions.

According to the rolling bearing geometry, the basic principle of kinematics and Hertz elastic contact theory, eccentric mass of mixing shaft, the centrifugal force of steel ball and gyroscopic moment are considered and the dynamic model of angular contact ball bearing is established in this paper. Using this model, the effects of preload, radial load and rotating speed on bearing stiffness and system dynamic characteristics are analyzed in detail. The results show that with the increase of radial load, the axial static stiffness decreases, while the radial stiffness increases gradually, and the increasing trend of radial static stiffness is more obvious than that of axial static stiffness. The increase of rotating speed will soften the stiffness of the bearing. The natural frequencies of each order of the system show a downward trend with the increase of rotating speed.

Fiber bragg grating has the advantages of simple structure, light weight, small volume, low energy consumption, high sensitivity and measurement accuracy, and is widely used in the field of structural health monitoring. the structure and basic principle of fiber bragg grating sensor are introduced. the change of temperature, stress and other parameters will lead to the change of reflection center wavelength. The strain and temperature sensitivity coefficients of Fiber Bragg Grating sensors with different wavelengths are obtained. The fiber Bragg grating strain sensor is developed, and the calibration experiment of the sensor is carried out. The loading equipment is the loading tester. The linearity of the Fiber Bragg Grating sensor is good, and it has a good prospect of engineering civil application.

The experiments were designed by testing methods and orthogonal single factor experimental design. XK5032C CNC milling machine, the equipment to achieve X-axis, Y-axis and 3-axis Z direction of the automatic feed, spindle cooling method using water-cooled. In different processing parameters (spindle speed, depth of cut and feed rate), measurement of the surface temperature of diamond tools. In the testing experiment result analysis, we conclude, the depth of cutting is the biggest influence on the surface temperature. From the orthogonal experiment data analysis, we found that, the temperature was reduced with spindle rotation but opposite with two other factors. By linear regression analysis. We get the best cutting results by choosing a large spindle rotation and a small feed rate.

The objective of this paper is research of main heat exchange characteristics in a complex multi-layer heat-exchanger with the purpose of determining heat exchanging process intensification dependencies and conditions during utilization of ventilation gas and emission low-grade heat with associated recovery of thermoelectricity.

The current evolution of the construction materials manufacturing industry requires an increased focus on the quantities of raw materials used, this can be adjusted by obtaining new sustainable materials with low energy and raw material consumption. The negative impact of the exploitation of natural resources is felt both from the point of view of the population's health and of the economic branch. Urban development and the progress of society have led to an uncontrolled increase in the amount of waste resulting from construction and demolition. Over the years it has been shown that waste can be reintroduced into the circuit for reuse. Waste reuse positively influences the regeneration of the environment and the improvement of economic resources. The waste used in this study is the brick powder type waste, this waste being part of the category of recyclable waste resulting from building, rehabilitation modernization and demolition of different constructions This article studies the mechanical characteristics at 3, 7 and 28 days, of a series of CSIV type millet recipes with brick powder waste. Brick powder can be used in building materials without depleting the consumption of raw materials and without degrading the environment.

In this paper, experiments and finite element methods are used to study the openings of the composite wing spar web of a civil aircraft. First, according to the design principles of composite laminates, determine the layup sequence and layup ratio of the spar, and then lay the beam webs and the beam edge strips integrally; then, calculate the equivalent of the spar by using the classic laminate theory Material properties, the method to calculate the equivalent elastic modulus of composite laminates of different thicknesses is derived; then, the influence of opening shape and opening angle on the strength of composite wing spar web under shear load is analyzed. Finally, the reinforcement design is carried out on the opening position. This research method not only solves specific engineering design problems, but also proposes a set of practical, cost-effective and efficient design methods for composite material opening shapes, which has a certain generality. Its design ideas and methods provide technical support for civil aircraft structural design.