Slip Form System Research Articles

Experimental Validation of Slip-Forming Using Ultrasonic Sensors.

Slip-forming in concrete construction enables the continuous placement of concrete using a climbing form, the efficiency of which depends on appropriate slip-up timing. This implies the importance of knowing accurately the development of concrete strength over time, which has been assessed manually to date in construction fields. This paper presents a method for automating the slip-forming process by determining the optimal slip-up time using the in-situ strength of concrete. The strength of concrete is evaluated by a formula relating the strength to the surface wave velocity measured with ultrasonic sensors. Specifically, this study validates the applicability of the slip-form system with ultrasonic sensors for continuously monitoring the hardening of concrete through its application in several construction sites. To this end, a slip-form system with a pair of ultrasonic modules at the bottom of the panel was tested and the time variation of surface wave velocity in the concrete material was monitored during the slip-forming process. The results show that the proposed method can provide the optimal slip-up time of the form to automate the slip-forming process. This approach is expected to apply to other construction technologies that required the continuous monitoring of concrete strength for construction efficiency as well as quality maintenance.

Stepwise Application of BIM-based Parametric Modeling to Tapered Slip-Form System

Slip-form technology, an automatic formwork system, has many benefits in construction industries and can shorten the construction time and reduce costs. However, slip-form systems have been designed using 2D drawing methods, which hinders the utilization of project information and impedes essential communication between project participants. The application of Building Information Modeling (BIM) technology, especially the parametric modeling method, can be an efficient solution.This study presents the beneficial effects of applying BIM technology to the design of a slip-form system. First, classification of a tapered slip-form was defined, based on Product Breakdown Structure (PBS) in a top-down approach. Then, working from the defined classification, 3D parametric models of a slip-form were constructed using the script language, SmartPart of Allplan (BIM tool). Finally, the established parametric model was tested by carrying out two different-height cases of tapered concrete pylons, automatically. This parametric design system could also be utilized to improve an efficiency of a formwork process.

Experimental verification of GFRP slip-form for in-situ application

This study was conducted to assess the field applicability of the Glass Fiber Reinforced Polymer (GFRP) slip-form proposed in previous studies by testing its performance-related properties in various experiments. We compared the initial curing temperature of concrete, which exerts the greatest impact on reducing the construction duration in the slip-form system, with that when using a steel slip-form. We measured the friction force to compare the cross section formability of the two methods. We then conducted a mock-up test on the basis of the experimental results and assessed its usability and field applicability. The GFRP form maintained a higher curing temperature than the steel form, and the difference in the curing temperature was larger with an increase in the air temperature and smaller with a decrease in the air temperature. The slip-up rate in the slip-forming was confirmed to be affected the most by the initial curing temperature of the concrete, whereas the cross-section formability was affected by the friction force and adhesion of the concrete. The results of the experiments verified that the GFRP slip-form efficiently overcomes the drawback of the steel slip-form system and maximizes the advantages of slip-forming.

A Development of Innovative Slip-Form System for Concrete Pylons

This study developed the innovative slip-form system for the construction of concrete pylons. The slip-up time of the slip-form is determined by estimating the compressive strength from surface wave velocity by the device attached to the slip form. GPS and tiltmeter are applied to secure the precise construction quality. The design of the slip form is verified in advance by BIM to validate its applicability through virtual assembly and construction. A slip form system is fabricated and mockup test is conducted to verify the performances of the developed techniques through the construction of a 10 m-high pylon with hollow section.

변단면 콘크리트 주탑공사의 슬립폼 시스템 적용을 위한 설계기술 연구

이 논문에서는 콘크리트 고주탑 시공을 위한 최첨단 공법이라 할 수 있는 슬립폼 시스템 공법의 기술자립을 목적으로 슬립폼 설계기술을 연구하였다. 대상 주탑은 10m의 높이를 갖으며 보통 케이블 교량의 주탑에서 적용하는 사각 중공 형상으로 계획하였다. 슬립폼 시스템은 콘크리트의 연속 타설을 고려하여 슬립폼이 연속적으로 단면의 치수변화와 두께변화에 대응할 수 있도록 설계하였다. 또한 시공시 슬립폼에 작용하는 다양한 하중에 대한 안전성을 검토하고, BIM에 의한 가상 시공으로 실용성을 사전 검증하였다. 설계된 제작 도면을 바탕으로 슬립폼 시스템을 제작하고 10m 높이의 주탑을 성공적으로 시공함으로써 개발된 변단면 슬립폼 시스템의 효율성을 입증하는 성과를 얻을 수 있었다. This paper studied design of slip form system considering the erection of a pylon mock-up. The height of the pylon is 10 m. A rectangular hollow cross-section was considered. The outer and inner dimensions of the pylons were varied with respect to the height. The thickness of 1 sides among the 4 faces were varied. Accordingly the slip form was designed to respond to continuous changes in its dimensions and thickness. Structural analysis was conducted to examine structural safety of the slip form. Virtual construction by BIM proved its practicality. The developed design technologies were successfully applied to the erection of a 10m high pylon executed for field verification test.

Experimental Study on Innovative Slip Form Method for the Construction of Tapered Concrete Pylon of Long-Span Cable Bridge

The construction of the three-dimensionally shaped pylons higher than 400 m requires a very high technological degree. It is known that the application of the tapered slip form method for the erection of the concrete pylon of long-span cable bridges offers the advantage of being significantly faster than applying the auto-climbing system (ACS) form method. Therefore, this study presents the development of an innovative slip form system for pylons with tapered cross-section. Surface wave inspection system is applied for the determination of slip-up time, wireless hydraulic control system is applied for auto rising, GPS system is used to manage the pylon configuration, and lightweight GFRP (Grass Fiber Reinforced Plastic) panels are applied in the slip form system. Small-scale tests were conducted three times to validate the performance of the developed core technologies, and full-scale tests were conducted twice to validate and verify the developed innovative slip form. The full-scale tapered concrete pylons have hollow shafts and a height of 10 m. The sectional dimensions are varied according to the construction height. The experimental constructions of the tapered pylons using the innovative slip form were conducted successfully. This system is the world’s first application of GFRP slip form panel.

A Study on the Quality Control of Concrete during the Slip Form Erection of Pylon

The construction market of super-high-rise buildings and long-span bridges has recognized unprecedented expansion owing to the development of high performance and high strength materials and the advances achieved in the design and construction technologies. In parallel to the lengthening and enlargement in scale of the structures, securing quality control technology of concrete while reducing the construction duration using improved construction methods emerges as a critical problem for concrete structures. In the erection of concrete pylons, slip forming represents the latest method offering the advantage of reducing drastically the construction duration compared to other methods by adopting automated slip-up of the forms and enabling 24-hour continuous placing. This study determines the slip-up time of the slip form by evaluating the early strength through the surface wave velocity and develops lightweight GFRP form in order to secure the quality of concrete during the slip form erection of pylons. A slip form system is fabricated and mockup test is conducted to verify the performances of the developed techniques through the construction of 10 m-high pylon with a hollow section.

Development of Highly Efficient Construction Technologies for Super Long Span Bridge

This paper presents highly efficient cable erection equipments and methods related to the construction of super-long-span bridges, construction technology of high towers and, technology for offshore foundations currently developed through a R&D on accelerated and cost-saving construction technology for long-span cable bridges to secure our international competitiveness. In the field of cable erection technology, AS and PPWS equipments for highly efficient erection of cable longer than 2000 m, world-class clamping bolt tensioning equipment and shape control system for super-long cable are under development. The technologies developed in the domain of construction of towers are tapered slip form system for the construction of 400 m high tower, shape and erection precision control of elevated tower and, lightweight and modular formwork for slip form system. In the domain of foundation construction, remote controlled survey equipment and analysis system for water-depth of 100 m and depth of 50 m, prediction and evaluation technology of optimal load carrying capacity and settlement complying with international standard and, highly efficient hybrid foundation construction technology suitable for ground acceleration of 0.5 g and deep soft soil are currently developed.

Development of an Efficient Tapered Slip-Form System Applying BIM Technology

Slip-form system constitutes the latest technology for the erection of elevated concrete pylons. This paper investigates the design of slip-form system applying BIM technology for the efficient development of the slip-form system. The considered pylon has a height of 10 m and presents the rectangular hollow section generally adopted in cable-supported bridges. The slip-form was thus designed to accommodate the tapered cross-section and changing thickness considering the continuous placing of concrete. In addition, the safety of the system was examined with regard to the various loads applied on the slip form along the construction. The design results could be verified visually through BIM and the applicability of the designed slip-form was validated in advance through virtual assembly and construction.

표면파 속도를 이용한 슬립폼 시스템 상승 시기 결정에 관한 연구

슬립폼 공법에 있어서 초기경화시간은 콘크리트가 거푸집에서 안전하게 빠져나올 수 있는 굳기를 갖게 되는 콘크리트 타설 후 경화시간으로써 슬립폼 시스템의 상승속도를 결정하는 중요한 요소이다. 따라서 슬립폼 시스템의 안전성 확보와 콘크리트의 시공품질을 확보하도록 초기경화시간을 파악하는 기술이 필요하다. 본 논문에서는 초음파를 이용하는 기법 중 표면파 속도를 이용하여 콘크리트의 경화정도를 파악하여 초기경화시간을 추정함으로써 슬립폼 시스템의 상승 시기를 결정하는 연구를 수행하였다. 관입저항시험과 압축강도시험을 수행하여 콘크리트의 초기경화시간과 압축강도와의 관계를 규명하였고, 또한 압축강도와 표면파 속도와의 관계를 규명하기 위해 초음파시험을 동시에 수행하였다. 표면파 속도를 측정하기 위해 연속웨이블릿변환을 사용하였으며, 이때 수치해석을 통해 연속웨이블릿변환의 사용에 대한 타당성을 입증하였다. 이로부터 슬립폼 시스템의 상승에 요구되는 표면파 전파속도를 제안하였으며, 슬립폼 시스템의 축소모형실험을 수행하여 제안한 표면파 속도가 슬립폼 상승 시기를 결정하는데 사용될 수 있음을 입증하였다. The early setting time of concrete is an important factor determining the slip up velocity of the slip-form system. Accordingly, need is for a technique evaluating the early setting time in order to secure the safety of the slip-form system and the construction quality of concrete. This paper intends to estimate the early setting time by evaluating the setting degree of concrete using surface wave velocity so as to determine the slip up time of the slip-form system. Penetration resistance test and compressive strength test are performed first to clarify the relationship between the early setting time of concrete and the compressive strength. Then, compressive strength test and ultrasonic wave test are conducted to examine the relation between the compressive strength and the surface wave velocity. Continuous wavelet transform is adopted to measure the surface wave velocity. Numerical analysis is carried out to demonstrate the appropriateness of the application of continuous wavelet transform. Based on these results, the propagation velocity of the surface wave required for the slip up of slip-form system is suggested. Finally, a reduced model test of the slip-form system is conducted to verify the feasibility of the proposed surface wave velocity for the determination of th slip up velocity.

Slip-Form Application to Concrete Structures

Because of superior speed and productivity, slip forms were extensively utilized as a potential formwork candidate in constructing concrete structures for the past few decades. Typical projects that employ this formwork technique are: Core of high-rise buildings, silos, telecommunication towers, cooling towers, heavy concrete offshore platforms, etc. The research presented in this paper aims at studying slip-form application to cores and silos, assessing its productivity, and determining its appropriate speed as well as auxiliary resource combinations. Simulation models are developed in which the potential control units in a slip-form system are described for cores and silos. Data are collected from several case study projects. A set of charts has been developed to predict productivity considering different stoppages, core cross section area, slipping (jacking) rate, and concrete placing methods. These charts play an essential role in managing slip-form application to cores and silos. Results show that the developed simulation models predict the productivity of case study projects with 99.70 and 99.30% accuracy for cores and silos, respectively. The presented research is relevant to both researchers and practitioners. It provides practitioners with charts that assist in scheduling and managing the required resources for slip-form application. In addition, it provides researchers with simulation models and framework for implementing slip forms to core and silo construction.

10万トン級石炭サイロの設計と施工(材料施工)

The world's biggest coal silos, with a total storage capacity of 100,000 tons of coal, are now being built for Maizuru Power Plant on Ohurapeninsula, Maizuru, Kyoto. This power plant is owned by The Kansai Electric Power Co., Inc. Prestressed concrete structure was adapted to withstand pressure by stored coal. Dynamic analyses considering interaction between the coal and the prestresed concrete silo were carried out as part of the seismic design. A new construction system called the "slip-up system", was developed as part of the project. This system uses an auto-climbing roof framing structure mounted on the slip form system. It reduces the amount of temporary support required, the cost and the construction time.

Estimating Resource Requirements at Conceptual Design Stage Using Neural Networks

Construction conceptual estimating models provide frameworks for evaluating different alternatives at the conceptual design stage. Estimations are prepared in practice primarily based on analogy with previous similar cases. A back-propagation neural-network model was developed in this study to estimate the construction resource requirements at the conceptual design stage. The developed model was applied on the construction of concrete silo walls built by using the slipform system. A set of 23 input attributes that mostly pertain to the determination of the resource requirements were identified. These input attributes include the bulk density of the stored materials, the wall-to-floor area of the silo complex, the number of lifting jacks of the slipform, and the number of stages through which the silo complex is constructed. The developed model was used to calculate the requirements from nine construction resource types. Outputs of the developed neural-network model were compared with estimations obtained from using multiple regression models. The results indicated that back-propagation neural-network models can be used satisfactorily to estimate the construction resource requirements at the conceptual design stage.

スリップフォーム工法によるPC造高架水槽の設計・施工

スリップフォーム工法によるPC造高架水槽の設計・施工