Formwork is the temporary moulds in the construction which is fabricated based on the drawing and design of the structure and into which the concrete is poured to form the required structure.Formwork is an essential p...Formwork is the temporary moulds in the construction which is fabricated based on the drawing and design of the structure and into which the concrete is poured to form the required structure.Formwork is an essential part of the construction as it has been used by the Romans.The formworks must be strong enough to withstand all types of loads.The joint must be in proper condition to avoid any kind of leakages.The materials used for the formworks should be economical,easily available and durable.The formworks can be made up of different materials such as plywood,steel,aluminum,composite material,etc.In steel formwork the plates used for the slab support are made up of galvanized steel and these are fabricated as per the requirements.Aluminum plates are used in the aluminum framework along with the other components made up of aluminum.The selection of a suitable framework is important in any project because it bears about 25%to 30%cost of the total cost of construction.In the present study,different types of formworks such as steel,plywood and aluminum were studied in a project and a comparison was made on the reusability and easiness in handling and maintenance.Also,a comparison of the formwork used in the construction of the 5th and 11th-floor tower based on the specific plan and drawing was done.The results showed that the aluminum formwork was found to be efficient and suitable among all formworks,although the cost was higher compared to other formwork materials.展开更多
Aiming at the problems of difficulty in balancing construction efficiency and quality,as well as the high safety risks of working at heights during the construction of main piers for highway bridges,this study takes a...Aiming at the problems of difficulty in balancing construction efficiency and quality,as well as the high safety risks of working at heights during the construction of main piers for highway bridges,this study takes a specific bridge project as an example to introduce the technology of hydraulically sliding formwork for the construction of main piers of highway bridges.An in-depth analysis of the project’s construction process found that this technology can effectively improve construction efficiency,ensure the quality of concrete pouring,and significantly reduce the potential safety hazards of working at heights.It provides a reliable technical solution for constructing the main piers of highway bridges and has important reference significance for similar projects.展开更多
A CaCO_(3)coating with good anticorrosion and adhesion performance was fabricated via ultrasound-assisted chemical conversion on AZ41 magnesium alloy,with a water-bath treated coating as a control.The coating formed o...A CaCO_(3)coating with good anticorrosion and adhesion performance was fabricated via ultrasound-assisted chemical conversion on AZ41 magnesium alloy,with a water-bath treated coating as a control.The coating formed on AZ41 mainly consists of an outer CaCO_(3)layer and an inner(Ca,Mg)CO_(3)layer.Surface characterizations were carried out to obtain the morphology and the chemical composition,mechanical tests were also adopted to assess the hardness and the adhesion of the coating prepared.Afterwards,the long-term corrosion resistance was investigated via electrochemical methods in the chloride-containing Portland cement system.Results show that the ultrasound-assisted coating exhibits higher mechanical properties.In addition,the corrosion resistance of the ultrasound-assisted coating is also higher than that of the bare AZ41 alloy and the water-bath treated coating.This could be due to the formation of a much more compact CaCO_(3)coating on AZ41 Mg alloy,which is mainly benefit from the assistance of the ultrasound.Ultrasound accelerates the nucleation of CaCO_(3)crystals and assists the removal of hydrogen bubbles.Additionally,corrosion mechanism was suggested and discussed for the CaCO_(3)coating.展开更多
This paper will discuss experiments using various forming systems combined with utilizing mechanical equipment,from cement mixers to excavators and skid steers with attachments,to accelerate construction of cob homes ...This paper will discuss experiments using various forming systems combined with utilizing mechanical equipment,from cement mixers to excavators and skid steers with attachments,to accelerate construction of cob homes and greatly reduce the labor involved.Cob is a colloquial term for monolithic adobe,and refers to a masonry building technique used since ancient times that uses locally-sourced clay as a binder,with various aggregates from sand to small grit or stone,woven together with straw or other fiber and built in continuous layers to form a monolithic structure.展开更多
A new constructive and technological approach was developed for the efficient production of large-dimensioned, curved freeform formworks, which allow the manufacturing of single and double-curved textile reinforced co...A new constructive and technological approach was developed for the efficient production of large-dimensioned, curved freeform formworks, which allow the manufacturing of single and double-curved textile reinforced concrete elements. The approach is based on a flexible, multi-layered formwork system, which consists of glass-fibre reinforced plastic (GFRP). Using the unusual structural behavior caused by anisotropy, these GFRP formwork elements permit a specific adjustment of defined curvature. The system design of the developed GFRP formwork and the concrete-lightweight-elements with stabilized spacer fabric was examined exhaustively. Prototypical curved freeform surfaces with different curvature radii were designed, numerically computed and produced. Furthermore, the fabric’s contour accuracy of the fabric was verified, and its integration was adjusted to loads.展开更多
Utilizing pre-cast ECC panels as participating permanent formwork of concrete members, and the validity of using ECC to disperse the single crack in concrete into multiple ones in ECC were studied. In the process, tot...Utilizing pre-cast ECC panels as participating permanent formwork of concrete members, and the validity of using ECC to disperse the single crack in concrete into multiple ones in ECC were studied. In the process, totally two kinds of ECC with different tensile properties, 7 series of flat panels with different top surface figures and 3 U-shape panels with different inner surface forms were investigated. To evaluate the performance of the permanent formworks, small ECC-concrete composite beams were cast and tested mechanically. The 4-point bending test results show that the use of pre-cast ECC panels as permanent formwork can significantly improve the load capacity and toughness of a concrete member, effectively dispersing single widely opened crack in concrete into multiple ones in ECC. Most permanent formworks show perfect bond with the concrete cast on them, while the ones with partially debonded zone achieve the best mechanical performance. The U-shape permanent formworks show better performances than the flat ones, achieving much betler improvements in both the load capacity and toughness, together with better crack width control.展开更多
By spraying concrete on inner surface,air-supported fabric structures can be used as formwork to construct reinforced concrete shell structures.The fabric formwork has the finished form of concrete structure.Large dev...By spraying concrete on inner surface,air-supported fabric structures can be used as formwork to construct reinforced concrete shell structures.The fabric formwork has the finished form of concrete structure.Large deviation from the desired shape of concrete shells still remains as central problem due to dead weight of concrete and less stiffness of fabric formwork.Polyurethane can be used not only as a bonding layer between fabrics and concrete but also as an additional stiffening layer.However,there is little research on mechanical behaviors of the polyurethane shell structure.This paper presents experimental studies on an inflated fabric model with and without polyurethane,including relief pressure tests,vertical loading tests and horizontal loading tests.Experimental results show that the additional polyurethane layer can significantly enhance the stiffness of the fabric formwork.Compared with the experiment,a numerical model using shell layered finite elements has a good prediction.The reinforcement by polyurethane to improve stiffness of air-supported fabric formwork is expected to be considered in the design and construction of the concrete shell,especially dealing with the advance of shape-control.展开更多
In order to determine the rational width of backfill in the goaf-side retained roadway, the deformation failure mechanism of surrounding rock in retained roadway is studied in the use of theoretical analysis, numerica...In order to determine the rational width of backfill in the goaf-side retained roadway, the deformation failure mechanism of surrounding rock in retained roadway is studied in the use of theoretical analysis, numerical simulation, etc., when the width of backfill is different. The results show that: with the increase of backfill width, the roof deformation above the backfill decreases; the outside of backfill obviously suffers from greater stress compared to the inner side of backfill; the damage firstly appears in the intersection of top backfill and roof; the plastic failure area is mainly distributed in the roof and floor of inside the roadway; 2 m wide backfill in the goaf-side retained roadway can meet the requirements of roadway deformation. Based on the original combination support of "anchor-mesh-belt-lock" in the haulage-track roadway, the study also considers the reinforced support of "anchor-mesh-belt" above the backfill, and 50 m ahead of working face, and 200 m behind the working face. This kind of support achieves a good result. The roadway deformation of field measurement shows that it can satisfy the need of the next working face.展开更多
Wall cracking and mold expanding due to concrete vibrations can be effectively solved through the application of precast normal-concrete composite shear walls infilled with self-compacting concrete(SCC). However, the ...Wall cracking and mold expanding due to concrete vibrations can be effectively solved through the application of precast normal-concrete composite shear walls infilled with self-compacting concrete(SCC). However, the high liquidity of SCC will induce a higher lateral pressure. Therefore, it is important to obtain a better understanding of the template lateral pressure. In this work, nine composite shear walls were experimentally investigated, focusing on the effects of two parameters, i.e., the casting rate and the section width of the formwork. The time-varying pressure was monitored during the SCC pouring. It is found that the increase of casting rate from 3.2 m/h to 10.3 m/h resulted in a higher maximum lateral pressure. The higher casting rate led to a longer time required for the lateral pressure to drop to a steady value. There was no correlation between the section width and the rate of decrease in the initial formwork pressure and stable value. Based on the test results, a formula considering the effect of casting speed for the calculation of SCC formwork pressure was established to fill the gap in the current standards and for engineering applications.展开更多
Rapid urbanization has led to a surge in the number of towering structures,and overturning is widely used because it can better accommodate the construction of shaped structures such as variable sections.The complexit...Rapid urbanization has led to a surge in the number of towering structures,and overturning is widely used because it can better accommodate the construction of shaped structures such as variable sections.The complexity of the construction process makes the construction risk have certain randomness,so this paper proposes a cloudbased coupled matter-element model to address the ambiguity and randomness in the safety risk assessment of overturning construction of towering structures.In the pretended model,the digital eigenvalues of the cloud model are used to replace the eigenvalues in the matter–element basic element,and calculate the cloud correlation of the risk assessment metrics through the correlation algorithm of the cloud model to build the computational model.Meanwhile,the improved hierarchical analysis method based on the cloud model is used to determine the weight of the index.The comprehensive evaluation scores of the evaluation event are then obtained through the weighted average method,and the safety risk level is determined accordingly.Through empirical analysis,(1)the improved hierarchical analysis method based on the cloud model can incorporate the data of multiple decisionmakers into the calculation formula to determine theweights,which makes the assessment resultsmore credible;(2)the evaluation results of the cloud-basedmatter-element coupledmodelmethod are basically consistent with those of the other two commonly used methods,and the confidence factor is less than 0.05,indicating that the cloudbased physical element coupled model method is reasonable and practical for towering structure overturning;(3)the cloud-based coupled element model method,which confirms the reliability of risk level by performing Spearman correlation on comprehensive assessment scores,can provide more comprehensive information of instances compared with other methods,and more comprehensively reflects the fuzzy uncertainty relationship between assessment indexes,which makes the assessment results more realistic,scientific and reliable.展开更多
The formwork and falsework in the construction of twin ribbed slab decks on a multi-span ecological bridge for a dual carriageway are presented. The bridge is situated in a valley plain which is crossed by small river...The formwork and falsework in the construction of twin ribbed slab decks on a multi-span ecological bridge for a dual carriageway are presented. The bridge is situated in a valley plain which is crossed by small rivers and was designed principally with the environment in mind. The bridge length is over 356 m, and the width of the decks is 11.5 m. For the bridge works, a simple conventional falsework system was chosen with steel frames for the supports and steel rolled beams for the decks. The formwork was constructed in solid timber and plywood as multiple-use panels. The falsework was designed in order to build the two 10-span bridge decks in stages. The decks are continuous cast-in-situ prestressed concrete twin rib with spans of 30 m, 34 m and 45 m. An individual falsework system was designed, which was easy to move transversally following completion of each stage for one deck. After finishing each stage, for the second deck, the falsework was dismantled and used again in the next construction fronts. An individual arrangement for the falsework along with timber pilings was used to cross the biggest river. The formwork timber panels were used several times in the multistage bridge construction. The adopted falsework system is very simple, but it allowed the speedy construction of the two decks where there were severe time constraints.展开更多
Improving the knowledge of rheological and tribological characteristics of fresh concrete is important to contribute to the progress of construction sites and the final quality of the work. The objective of this study...Improving the knowledge of rheological and tribological characteristics of fresh concrete is important to contribute to the progress of construction sites and the final quality of the work. The objective of this study is to identify the effect of a superplasticizer based on polycarboxylic ether on the tribological behavior of fresh concrete at the concrete/formwork and concrete/oil/formwork interfaces. Friction tests on fresh concrete were carried out using a plan/plan tribometer. In order to study the behavior of the superplasticizer close to the formwork, three concretes with 30% of paste and different dosage of superplasticizer were formulated. The results show that the increase of the dosage of superplasticizer reduces the friction stress. The properties of the superplasticizer generate a deflocculating action of concrete grains and lead to a stabilisation of the soap-oil micellae present in the vicinity of the formwork. Thus, the efficiency of superplasticizer depends on the quantity of fines, on the quantity of soap formed and so, on the release agent formulation.展开更多
This paper presents the development and technological implementation of textile reinforced concrete (TRC) shells with integrated functions, such as illumination and light control. In that regard the establishment of m...This paper presents the development and technological implementation of textile reinforced concrete (TRC) shells with integrated functions, such as illumination and light control. In that regard the establishment of material, structural and technological foundations along the entire value chain are of central importance: From the light-weight design idea to the demonstrator and reference object, to the technological implementation for the transfer of the research results into practice. The development of the material included the requirement-oriented composition of a high-strength fine grained concrete with an integrated textile reinforcement, such as carbon knitted fabrics. Innovations in formwork solutions provide new possibilities for concrete constructions. So, a bionic optimized shape of the pavilion was developed, realized by four connected TRC-lightweight-shells. The thin-walled TRC-shells were manufactured with a formwork made of glass-fibre reinforced polymer (GFRP). An advantage of the GFRP-formwork is the freedom of design concerning the formwork shape. Moreover, an excellent concrete quality can be achieved, while the production of the precast concrete components is simple and efficient simultaneously. After the production the new TRC-shells were installed and assembled on the campus of TU-Chemnitz. A special feature of the research pavilions are the LED light strips integrated in the shell elements, providing homogeneous illumination.展开更多
Formwork construction has been the important and difficult of the construction process, so the design plan is very important. This paper relies on the Shun Ping Yu subordinate Fertgbo bridge rebuilding project, detail...Formwork construction has been the important and difficult of the construction process, so the design plan is very important. This paper relies on the Shun Ping Yu subordinate Fertgbo bridge rebuilding project, detailing the cast-in-place box beam formwork support system safety special construction plan, focuses on box girder formwork design scheme of foundation design, box girder bracket design and box girder formwork design, to provide a reasonable reference for similar projects.展开更多
The construction quality of high formwork erection will directly affect the structural safety of the project. Therefore, in the construction process of high formwork erection, the relevant construction personnel must ...The construction quality of high formwork erection will directly affect the structural safety of the project. Therefore, in the construction process of high formwork erection, the relevant construction personnel must strictly abide by the specifications and correctly construct, so as to ensure the construction quality of the construction project. In view of the danger and complexity of the construction of the high formwork support system, it is easy to lose stability in the pouring process, which seriously endangers the personal safety of the construction personnel. In this paper, aiming at the frequent construction safety problems of the high formwork support system, through the accident case analysis, some measures and suggestions are put forward to ensure the construction safety.展开更多
Based on the construction technology of aluminum alloy formwork and traditional wood formwork, the contents in the construction drawings can be constructed at one time and deepened at one time in combination with the ...Based on the construction technology of aluminum alloy formwork and traditional wood formwork, the contents in the construction drawings can be constructed at one time and deepened at one time in combination with the site. The common quality problems that are easy to appear can be controlled in the construction process, which can improve the construction quality of aluminum alloy formwork to a large extent. If the following construction points are controlled in the construction process, It can maximize the construction quality of aluminum alloy formwork and enhance economic benefits.展开更多
With the continuous expansion of the scale of the building, people from all walks of life pay more attention to the engineering construction, especially the application of high formwork technology. In order to enhance...With the continuous expansion of the scale of the building, people from all walks of life pay more attention to the engineering construction, especially the application of high formwork technology. In order to enhance the application effect of the technology, its application conditions have new requirements. As the high formwork construction is the main content of engineering construction, it is conducive to improve the quality of engineering construction and increase the economic benefits of construction, so it is of great value to pay attention to it. It is worth mentioning that there are still some problems in the application of high formwork technology in construction engineering, which restrict its further development.展开更多
This paper briefly describes the design, construction technology and quality control of tall formwork of the second phase bulk cargo corridor transfer station in Guoyuan Port, which can provide some reference for simi...This paper briefly describes the design, construction technology and quality control of tall formwork of the second phase bulk cargo corridor transfer station in Guoyuan Port, which can provide some reference for similar projects in the later period. The bulk cargo export of orchard adopts the technological scheme of arc track loader+belt conveyor. The whole bulk cargo belt conveyor system is connected with the rear railway system through the belt conveyor main corridor located on the east side of the orchard operation area.展开更多
The application of mobile formwork cast-in-situ beam technology is conducive to providing quality assurance for bridge constructions.At the same time,it can improve the overall mechanization level of the construction ...The application of mobile formwork cast-in-situ beam technology is conducive to providing quality assurance for bridge constructions.At the same time,it can improve the overall mechanization level of the construction process and further accelerate the construction progress,so as to shorten the construction period and improve the economic benefits of enterprises.In fact,this construction method has been widely applied.In order to assure a positive outcome from the use of this technology,this paper analyzes the application of mobile formwork cast-in-situ beam technology in bridge construction to provide reference.展开更多
Combined with the construction of prestressed continuous box girder of Bailongjiang super large bridge in Xiazongjiaba of WJSJ2 contract section of G8513 Pingliang to Mianyang national expressway and Wudu to Jiuzhaigo...Combined with the construction of prestressed continuous box girder of Bailongjiang super large bridge in Xiazongjiaba of WJSJ2 contract section of G8513 Pingliang to Mianyang national expressway and Wudu to Jiuzhaigou (Ganchuan boundary), this paper analyzed the application of prestressed continuous box girder support formwork design, concrete pouring technology, prestressed steel tendon tension sequence and vacuum assisted grouting technology.展开更多
文摘Formwork is the temporary moulds in the construction which is fabricated based on the drawing and design of the structure and into which the concrete is poured to form the required structure.Formwork is an essential part of the construction as it has been used by the Romans.The formworks must be strong enough to withstand all types of loads.The joint must be in proper condition to avoid any kind of leakages.The materials used for the formworks should be economical,easily available and durable.The formworks can be made up of different materials such as plywood,steel,aluminum,composite material,etc.In steel formwork the plates used for the slab support are made up of galvanized steel and these are fabricated as per the requirements.Aluminum plates are used in the aluminum framework along with the other components made up of aluminum.The selection of a suitable framework is important in any project because it bears about 25%to 30%cost of the total cost of construction.In the present study,different types of formworks such as steel,plywood and aluminum were studied in a project and a comparison was made on the reusability and easiness in handling and maintenance.Also,a comparison of the formwork used in the construction of the 5th and 11th-floor tower based on the specific plan and drawing was done.The results showed that the aluminum formwork was found to be efficient and suitable among all formworks,although the cost was higher compared to other formwork materials.
文摘Aiming at the problems of difficulty in balancing construction efficiency and quality,as well as the high safety risks of working at heights during the construction of main piers for highway bridges,this study takes a specific bridge project as an example to introduce the technology of hydraulically sliding formwork for the construction of main piers of highway bridges.An in-depth analysis of the project’s construction process found that this technology can effectively improve construction efficiency,ensure the quality of concrete pouring,and significantly reduce the potential safety hazards of working at heights.It provides a reliable technical solution for constructing the main piers of highway bridges and has important reference significance for similar projects.
基金the National Key Research and Development Program of China(Grant No.2021YFB3701100)the Natural Science Foundation Commission of China(Grant Nos.U20A20234and 51874062)+1 种基金Chongqing Foundation and Advanced Research Project(Grant No.cstc2019jcyj-zdxmX 0010)the Science and Technology Major Project of Shanxi Province(Grant No.20191102008)。
文摘A CaCO_(3)coating with good anticorrosion and adhesion performance was fabricated via ultrasound-assisted chemical conversion on AZ41 magnesium alloy,with a water-bath treated coating as a control.The coating formed on AZ41 mainly consists of an outer CaCO_(3)layer and an inner(Ca,Mg)CO_(3)layer.Surface characterizations were carried out to obtain the morphology and the chemical composition,mechanical tests were also adopted to assess the hardness and the adhesion of the coating prepared.Afterwards,the long-term corrosion resistance was investigated via electrochemical methods in the chloride-containing Portland cement system.Results show that the ultrasound-assisted coating exhibits higher mechanical properties.In addition,the corrosion resistance of the ultrasound-assisted coating is also higher than that of the bare AZ41 alloy and the water-bath treated coating.This could be due to the formation of a much more compact CaCO_(3)coating on AZ41 Mg alloy,which is mainly benefit from the assistance of the ultrasound.Ultrasound accelerates the nucleation of CaCO_(3)crystals and assists the removal of hydrogen bubbles.Additionally,corrosion mechanism was suggested and discussed for the CaCO_(3)coating.
文摘This paper will discuss experiments using various forming systems combined with utilizing mechanical equipment,from cement mixers to excavators and skid steers with attachments,to accelerate construction of cob homes and greatly reduce the labor involved.Cob is a colloquial term for monolithic adobe,and refers to a masonry building technique used since ancient times that uses locally-sourced clay as a binder,with various aggregates from sand to small grit or stone,woven together with straw or other fiber and built in continuous layers to form a monolithic structure.
基金supported by the Priority Program SPP 1542 of the German Research Foundation(DFG)
文摘A new constructive and technological approach was developed for the efficient production of large-dimensioned, curved freeform formworks, which allow the manufacturing of single and double-curved textile reinforced concrete elements. The approach is based on a flexible, multi-layered formwork system, which consists of glass-fibre reinforced plastic (GFRP). Using the unusual structural behavior caused by anisotropy, these GFRP formwork elements permit a specific adjustment of defined curvature. The system design of the developed GFRP formwork and the concrete-lightweight-elements with stabilized spacer fabric was examined exhaustively. Prototypical curved freeform surfaces with different curvature radii were designed, numerically computed and produced. Furthermore, the fabric’s contour accuracy of the fabric was verified, and its integration was adjusted to loads.
基金Funded by the Hong Kong Research Grant Council(No. CERGUST6138/04E)the Key Program of National Natural Science Foundation of China(No. 50438010)the Research & Application of Key Technology for the South-North Water Transfer Project Construction in China(No.JGZXJJ2006-13)
文摘Utilizing pre-cast ECC panels as participating permanent formwork of concrete members, and the validity of using ECC to disperse the single crack in concrete into multiple ones in ECC were studied. In the process, totally two kinds of ECC with different tensile properties, 7 series of flat panels with different top surface figures and 3 U-shape panels with different inner surface forms were investigated. To evaluate the performance of the permanent formworks, small ECC-concrete composite beams were cast and tested mechanically. The 4-point bending test results show that the use of pre-cast ECC panels as permanent formwork can significantly improve the load capacity and toughness of a concrete member, effectively dispersing single widely opened crack in concrete into multiple ones in ECC. Most permanent formworks show perfect bond with the concrete cast on them, while the ones with partially debonded zone achieve the best mechanical performance. The U-shape permanent formworks show better performances than the flat ones, achieving much betler improvements in both the load capacity and toughness, together with better crack width control.
基金Projects(51178263,51378307)supported by the National Natural Science Foundation of China
文摘By spraying concrete on inner surface,air-supported fabric structures can be used as formwork to construct reinforced concrete shell structures.The fabric formwork has the finished form of concrete structure.Large deviation from the desired shape of concrete shells still remains as central problem due to dead weight of concrete and less stiffness of fabric formwork.Polyurethane can be used not only as a bonding layer between fabrics and concrete but also as an additional stiffening layer.However,there is little research on mechanical behaviors of the polyurethane shell structure.This paper presents experimental studies on an inflated fabric model with and without polyurethane,including relief pressure tests,vertical loading tests and horizontal loading tests.Experimental results show that the additional polyurethane layer can significantly enhance the stiffness of the fabric formwork.Compared with the experiment,a numerical model using shell layered finite elements has a good prediction.The reinforcement by polyurethane to improve stiffness of air-supported fabric formwork is expected to be considered in the design and construction of the concrete shell,especially dealing with the advance of shape-control.
基金Financial support for this work was provided by Chinese National 863 High Technology Plan (No. 2012AA062101)the Priority Academic Program Development of Jiangsu Higher Education Institutions (No. SZBF2011-6-B35)the Graduate Students Innovation Fund of Colleges and Universities in Jiangsu Province (No.CXZZ12_0950)
文摘In order to determine the rational width of backfill in the goaf-side retained roadway, the deformation failure mechanism of surrounding rock in retained roadway is studied in the use of theoretical analysis, numerical simulation, etc., when the width of backfill is different. The results show that: with the increase of backfill width, the roof deformation above the backfill decreases; the outside of backfill obviously suffers from greater stress compared to the inner side of backfill; the damage firstly appears in the intersection of top backfill and roof; the plastic failure area is mainly distributed in the roof and floor of inside the roadway; 2 m wide backfill in the goaf-side retained roadway can meet the requirements of roadway deformation. Based on the original combination support of "anchor-mesh-belt-lock" in the haulage-track roadway, the study also considers the reinforced support of "anchor-mesh-belt" above the backfill, and 50 m ahead of working face, and 200 m behind the working face. This kind of support achieves a good result. The roadway deformation of field measurement shows that it can satisfy the need of the next working face.
基金Funded by the National Natural Science Foundation of China(No.51178218)the Cooperation Project of Yangzhou Science and Technology Bureau(YZ2016267)
文摘Wall cracking and mold expanding due to concrete vibrations can be effectively solved through the application of precast normal-concrete composite shear walls infilled with self-compacting concrete(SCC). However, the high liquidity of SCC will induce a higher lateral pressure. Therefore, it is important to obtain a better understanding of the template lateral pressure. In this work, nine composite shear walls were experimentally investigated, focusing on the effects of two parameters, i.e., the casting rate and the section width of the formwork. The time-varying pressure was monitored during the SCC pouring. It is found that the increase of casting rate from 3.2 m/h to 10.3 m/h resulted in a higher maximum lateral pressure. The higher casting rate led to a longer time required for the lateral pressure to drop to a steady value. There was no correlation between the section width and the rate of decrease in the initial formwork pressure and stable value. Based on the test results, a formula considering the effect of casting speed for the calculation of SCC formwork pressure was established to fill the gap in the current standards and for engineering applications.
基金funded by China Railway No.21 Bureau Group No.1 Engineering Co.,Ltd.,Grant No.202209140002.
文摘Rapid urbanization has led to a surge in the number of towering structures,and overturning is widely used because it can better accommodate the construction of shaped structures such as variable sections.The complexity of the construction process makes the construction risk have certain randomness,so this paper proposes a cloudbased coupled matter-element model to address the ambiguity and randomness in the safety risk assessment of overturning construction of towering structures.In the pretended model,the digital eigenvalues of the cloud model are used to replace the eigenvalues in the matter–element basic element,and calculate the cloud correlation of the risk assessment metrics through the correlation algorithm of the cloud model to build the computational model.Meanwhile,the improved hierarchical analysis method based on the cloud model is used to determine the weight of the index.The comprehensive evaluation scores of the evaluation event are then obtained through the weighted average method,and the safety risk level is determined accordingly.Through empirical analysis,(1)the improved hierarchical analysis method based on the cloud model can incorporate the data of multiple decisionmakers into the calculation formula to determine theweights,which makes the assessment resultsmore credible;(2)the evaluation results of the cloud-basedmatter-element coupledmodelmethod are basically consistent with those of the other two commonly used methods,and the confidence factor is less than 0.05,indicating that the cloudbased physical element coupled model method is reasonable and practical for towering structure overturning;(3)the cloud-based coupled element model method,which confirms the reliability of risk level by performing Spearman correlation on comprehensive assessment scores,can provide more comprehensive information of instances compared with other methods,and more comprehensively reflects the fuzzy uncertainty relationship between assessment indexes,which makes the assessment results more realistic,scientific and reliable.
文摘The formwork and falsework in the construction of twin ribbed slab decks on a multi-span ecological bridge for a dual carriageway are presented. The bridge is situated in a valley plain which is crossed by small rivers and was designed principally with the environment in mind. The bridge length is over 356 m, and the width of the decks is 11.5 m. For the bridge works, a simple conventional falsework system was chosen with steel frames for the supports and steel rolled beams for the decks. The formwork was constructed in solid timber and plywood as multiple-use panels. The falsework was designed in order to build the two 10-span bridge decks in stages. The decks are continuous cast-in-situ prestressed concrete twin rib with spans of 30 m, 34 m and 45 m. An individual falsework system was designed, which was easy to move transversally following completion of each stage for one deck. After finishing each stage, for the second deck, the falsework was dismantled and used again in the next construction fronts. An individual arrangement for the falsework along with timber pilings was used to cross the biggest river. The formwork timber panels were used several times in the multistage bridge construction. The adopted falsework system is very simple, but it allowed the speedy construction of the two decks where there were severe time constraints.
文摘Improving the knowledge of rheological and tribological characteristics of fresh concrete is important to contribute to the progress of construction sites and the final quality of the work. The objective of this study is to identify the effect of a superplasticizer based on polycarboxylic ether on the tribological behavior of fresh concrete at the concrete/formwork and concrete/oil/formwork interfaces. Friction tests on fresh concrete were carried out using a plan/plan tribometer. In order to study the behavior of the superplasticizer close to the formwork, three concretes with 30% of paste and different dosage of superplasticizer were formulated. The results show that the increase of the dosage of superplasticizer reduces the friction stress. The properties of the superplasticizer generate a deflocculating action of concrete grains and lead to a stabilisation of the soap-oil micellae present in the vicinity of the formwork. Thus, the efficiency of superplasticizer depends on the quantity of fines, on the quantity of soap formed and so, on the release agent formulation.
文摘This paper presents the development and technological implementation of textile reinforced concrete (TRC) shells with integrated functions, such as illumination and light control. In that regard the establishment of material, structural and technological foundations along the entire value chain are of central importance: From the light-weight design idea to the demonstrator and reference object, to the technological implementation for the transfer of the research results into practice. The development of the material included the requirement-oriented composition of a high-strength fine grained concrete with an integrated textile reinforcement, such as carbon knitted fabrics. Innovations in formwork solutions provide new possibilities for concrete constructions. So, a bionic optimized shape of the pavilion was developed, realized by four connected TRC-lightweight-shells. The thin-walled TRC-shells were manufactured with a formwork made of glass-fibre reinforced polymer (GFRP). An advantage of the GFRP-formwork is the freedom of design concerning the formwork shape. Moreover, an excellent concrete quality can be achieved, while the production of the precast concrete components is simple and efficient simultaneously. After the production the new TRC-shells were installed and assembled on the campus of TU-Chemnitz. A special feature of the research pavilions are the LED light strips integrated in the shell elements, providing homogeneous illumination.
文摘Formwork construction has been the important and difficult of the construction process, so the design plan is very important. This paper relies on the Shun Ping Yu subordinate Fertgbo bridge rebuilding project, detailing the cast-in-place box beam formwork support system safety special construction plan, focuses on box girder formwork design scheme of foundation design, box girder bracket design and box girder formwork design, to provide a reasonable reference for similar projects.
文摘The construction quality of high formwork erection will directly affect the structural safety of the project. Therefore, in the construction process of high formwork erection, the relevant construction personnel must strictly abide by the specifications and correctly construct, so as to ensure the construction quality of the construction project. In view of the danger and complexity of the construction of the high formwork support system, it is easy to lose stability in the pouring process, which seriously endangers the personal safety of the construction personnel. In this paper, aiming at the frequent construction safety problems of the high formwork support system, through the accident case analysis, some measures and suggestions are put forward to ensure the construction safety.
文摘Based on the construction technology of aluminum alloy formwork and traditional wood formwork, the contents in the construction drawings can be constructed at one time and deepened at one time in combination with the site. The common quality problems that are easy to appear can be controlled in the construction process, which can improve the construction quality of aluminum alloy formwork to a large extent. If the following construction points are controlled in the construction process, It can maximize the construction quality of aluminum alloy formwork and enhance economic benefits.
文摘With the continuous expansion of the scale of the building, people from all walks of life pay more attention to the engineering construction, especially the application of high formwork technology. In order to enhance the application effect of the technology, its application conditions have new requirements. As the high formwork construction is the main content of engineering construction, it is conducive to improve the quality of engineering construction and increase the economic benefits of construction, so it is of great value to pay attention to it. It is worth mentioning that there are still some problems in the application of high formwork technology in construction engineering, which restrict its further development.
文摘This paper briefly describes the design, construction technology and quality control of tall formwork of the second phase bulk cargo corridor transfer station in Guoyuan Port, which can provide some reference for similar projects in the later period. The bulk cargo export of orchard adopts the technological scheme of arc track loader+belt conveyor. The whole bulk cargo belt conveyor system is connected with the rear railway system through the belt conveyor main corridor located on the east side of the orchard operation area.
文摘The application of mobile formwork cast-in-situ beam technology is conducive to providing quality assurance for bridge constructions.At the same time,it can improve the overall mechanization level of the construction process and further accelerate the construction progress,so as to shorten the construction period and improve the economic benefits of enterprises.In fact,this construction method has been widely applied.In order to assure a positive outcome from the use of this technology,this paper analyzes the application of mobile formwork cast-in-situ beam technology in bridge construction to provide reference.
文摘Combined with the construction of prestressed continuous box girder of Bailongjiang super large bridge in Xiazongjiaba of WJSJ2 contract section of G8513 Pingliang to Mianyang national expressway and Wudu to Jiuzhaigou (Ganchuan boundary), this paper analyzed the application of prestressed continuous box girder support formwork design, concrete pouring technology, prestressed steel tendon tension sequence and vacuum assisted grouting technology.
