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
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
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
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
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
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
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
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.
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.
