Fabric Formwork Research Articles

Application of Fabric Formwork based on a Truchet Tiling Pattern for Planar Surfaces

Application of Fabric Formwork based on a Truchet Tiling Pattern for Planar Surfaces

Fabric Formed Unstabilized Poured Earth: Four-Dimensional Wall Systems

This paper presents prototype design research into the drying, shrinkage, and cracking of unstabilized fabric-formed poured earth. An unstabilized poured earth mix became self-supporting in fabric formwork and hardened to the touch after 11 days. The same poured earth mix in conventional concrete planar impermeable formwork was wet and pliable after 22 days. Fabric formwork hung by expandable elastics also reduced cracking, allowing material shrinkage at form ties. Poured earth without Portland cement stabilization can create non-structural wall forms with less transportation of material to the site and less overall use of Portland cement. The mix tested here would match a site soil with a 29–30% illite or kaolinite clay content found by the authors in the southwestern United States.

Structural design of a lattice pykrete tower

Pykrete is a material used for temporary structures in cold environments. In the last decade, this material has generally been used in shell structures that were constructed using inflatable fabric formwork and ropes. Recently, research has been carried out to use pykrete in structures made of linear elements and some structures of low heights have been able to be built.A pykrete tower-like structure was built in 2019 for the International Ice and Snow Innovation Design and Construction competition, based on a proposal made by the Eindhoven University of Technology. This structure raised to 11 m, making it the tallest pykrete structure with linear elements built so far. This paper describes the base concepts, design process, testing methodology and building methods of this tower.

On the possibility of using damaged plasticity models in the assessment of structural response of gravity beams

Advent of concrete damaged plasticity material models has drastically improved the accuracy in predicting the structural response of concrete structural elements using finite element Analysis. However, exploration of the accuracy of this method in analysing complex concrete forms is scanty. Gravity Beams, a term coined in this investigation, are those beams in which gravity is used to design the topology of beam form conjointly with the novel manufacturing strategy ‘Fabric Formwork’. In this investigation these beam forms were numerically analysed using prevalent material and damage models. Numerical structural response was evaluated using these models and compared to experimental response. It was deduced from the comparative evaluation that numerical models closely predict the structural response of gravity beams. Moreover, dissimilarity analysis revealed that the diversion of the results was due the shape error between Modelled gravity beams, which were used for numerical analysis, and actual 3D scanned beams. It was deduced after analysis of experimental and numerical failure patterns that local imperfections also play a major role in the deviation in the numerical model. Furthermore, cross-sectional proportion ratio (CPR) was also introduced to give a numerical identity to gravity beams. This ratio was used to frame a parametric comparison of gravity beams and the corresponding structural response, to explore the parametric dependency.

Employing B-Spline approach in parametric assessment of catenary shaped fabric-formed concrete beams

Concrete significantly contributes to carbon emissions and ever growing need for infrastructure consequently demands an increase in this consumption. Ergo, making the reduction of concrete consumption a challenging task. This challenge can be tackled by nature driven approaches, which provide an intuitive strategy to achieve efficient structures with reduced volumes. In this research, parametric assessment of catenary shaped fabric-formed concrete beams was conducted. Bezier spline was used to frame the longitudinal profile with mid-span depth (dc), support depth (ds) and breadth (b) as guiding parameters for the overall topology of the beam forms. Fabric formwork manufacturing approach was employed, given the hanging nature of the topology of resulting beam forms The main objective of this investigation was to assess the structural response of these beams at various parametric cross-sectional variations with dc to ds ratio as 2:1. All beam specimens exhibited a flexural response hence signifying the efficacy of 2:1 ratio. Moreover, higher ds/b values exhibited an extended plastic phase. Whereas, an increase in volume prediction error was recorded as a result. Response surface methodology model equations predict elastic and plastic failures to an accuracy of about 85%.

Performance Evaluation of Woven Polyethylene Formwork on Tie Beam and Pile Cap Structure in Terms of Cost and Time

One of the most important components in the construction execution is concrete works. Therefore, we need formworks to form the structural elements that are planned in a construction process. In the process, an economical alternative needs to be taken regarding choosing formwork material to get more benefits, both in terms of cost and time. Fabric formwork can be an alternative solution for formwork material. An example of a feasible formwork material alternative is woven polyethylene-based formwork. The purpose of this research is to evaluate the performance value of woven polyethylene formwork and compare it with the conventional formworks such as wood and brick in terms of cost and time. Field observations and literature reviews have been done to answer these questions. By using woven polyethylene formwork on tie beam and pile cap structure, it was found that the average time and the investment cost of installation are consecutively 344.23 s/m2 and IDR75000 which is faster and cheaper than using conventional ones.

Precise imprecision: flexible construction with robotics

This research demonstrates a new methodology—stack casting, which combines fabric formwork and robotic assembly. In the following research, a robot placed a textile mold on top of a precast environment to erect a significant architectural object. Through this method the robotic casting process obtained further contextual information to create highly customized assemblies. The natural form-fit boundary of the fabric strengthened the identification between global and local systems. As the digital method met the natural form-finding process, an interactive tectonic was generated—calibrating itself for any composition and accommodating deviations in geometry. Driven by the correspondence between digital and physical, the technique extended the building method of a dry-fitted cast in situ wall. To build a full-scale prototype, robotic stack casting collaborated with other versatile methods to invent new set-up strategies, which link to both on-and off-site construction. This research is part of a bigger picture rising in soft robotics. By interpreting unique forming into the computational design, precise and imprecise fabrication were redefined in a playful phenomenon. In traditional robotic stacking, the robot bridges the digital and physical world but its lack of adaptivity causes problem when placing imprecise objects. In this research’s process, the use of inexact fabric molds fixed the tolerance and found centers of gravity through relative reactions. They adjusted to the unique personal properties of their surroundings and compensated for discrepancies in material. As an alternative to the application of sensor feedback for accommodating tolerance in material, the use of stack casting digital formwork instead adjusts and reshapes the non-ideal masonry from the real-time architectural context. This playful process opens the door to further imaginations from design to build.

Fabric-Lined Tensile Formwork for Cast-in-Place Concrete Walls

This research explores fabric-lined tensile formwork systems for casting structural concrete walls with an architectural finish. To mitigate the prohibitive cost of cast-in-place architectural concrete formwork, this research aims to minimize the materials consumed by the falsework and the specialty equipment required for its installation. Following a survey of contemporary tensile formwork, investigations into two fabric-lined tensile systems are presented: System-A, a scaffolding based system and System-B which incorporates an internal, tensile structure. This design-build research is conducted through a series of physical models in which each system culminates in full-scale prototypes for cast-in-place concrete walls. In addition to the unique architectural finish of the fabric formwork, the full-scale prototypes of System-A and System-B and are assessed for their ability to maintain select industry standards for structural integrity. The paper concludes with identifying future areas of research and questioning the role of specialty equipment and falsework in the construction of complex concrete forms.

A state of the art on the structural performance of fabric formwork systems

A state of the art on the structural performance of fabric formwork systems

Reinforcement by polyurethane to stiffness of air-supported fabric formwork for concrete shell construction

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.

Computational design of fabric formwork

We present an inverse design tool for fabric formwork - a process where flat panels are sewn together to form a fabric container for casting a plaster sculpture. Compared to 3D printing techniques, the benefit of fabric formwork is its properties of low-cost and easy transport. The process of fabric formwork is akin to molding and casting but having a soft boundary. Deformation of the fabric container is governed by force equilibrium between the pressure forces from liquid fill and tension in the stretched fabric. The final result of fabrication depends on the shapes of the flat panels, the fabrication orientation and the placement of external supports. Our computational framework generates optimized flat panels and fabrication orientation with reference to a target shape, and determines effective locations for external supports. We demonstrate the function of this design tool on a variety of models with different shapes and topology. Physical fabrication is also demonstrated to validate our approach.

HYPAR ROBOTIC FABRIC FORMWORK FOR CREATING HYPERBOLIC PARABOLOID PANELS

HYPAR ROBOTIC FABRIC FORMWORK FOR CREATING HYPERBOLIC PARABOLOID PANELS

Serviceability of non-prismatic concrete beams: Combined-interaction method

Interest in the shape optimisation of concrete members is increasing alongside the availability of fabric formwork as a relatively simple technique to cast non-prismatic concrete structures. Research has shown that up 40% of concrete can be saved when shape optimised concrete beams are cast in fabric forms. However, optimisation results in members with non-uniform cross-sections and the resulting beam is less stiff than an equivalent strength prismatic beam. Serviceability, rather than strength, may govern the design of such members and therefore understanding the serviceability behaviour (deflection and cracking) of shape optimised concrete members becomes is a critical design consideration. There are many methods which can be used to evaluate serviceability behaviour of reinforced concrete beams, including the full-interaction method, which assumes no slip between the reinforcement and the surrounding concrete, and the partial-interaction method which accounts for slip. The full-interaction method is based on a smeared crack approach and so is unsuited for the prediction of cracking behaviour. The partial-interaction method, on the other hand, assumes that cracks form through bond-stress transfer only. In the case of non-prismatic concrete beams, the cracking capacity varies along the member. Therefore, cracking can occur over extended regions (full and partial bond interaction regions) and so it can be argued that neither of these models is fully suitable for the prediction of deflections and cracking of shape-optimised concrete beams. In this paper, a novel combined-interaction method is, for the first time, presented to predict the serviceability behaviour of non-prismatic statically determinate concrete beams by simulating both full and partial bond interactions at different cracked and uncracked regions along the length of the member. In order to validate this approach, two non-prismatic simply supported beams were cast and tested. The test results for deflections, crack widths and crack spacings were in good agreement with the predicted results.

Adaptive Strategies for Mud Shell Robotic Fabrication

The digital fabrication of monolithic shell structures is presenting some challenges related to the interface between computational design, materialist, and fabrication techniques. This research proposes a singular method for the sequential robotic spray deposition in layers of diverse clay mixes over a temporary fabric form-work pulled in between peripheral and cross section arches. This process relies mainly on the continuity of the construction phases for stability and durability but has encountered some challenges in physical tests related to sagging, displacement, and deformations during the robotic deposition of the material. Adaptive strategies during the digital fabrication stages are proposed for a sequential exploration of the geometry, structural analysis, and construction techniques. Alternative adjustments of protocols for the robotic material deposition include both predictable and unsuspected behaviors preventing the structure to reach non-viable geometric thresholds. Two case studies of physical tests describe, analyze, and simulate some of these strategies and identify specific parameters inquiring the sequential adjustments of the robotic material deposition. These strategies will drive future full-scale tests within a sustainable use of materials and adaptive construction methods, seeking an optimized structural performance that could open a new chapter for the digital fabrication of earthen shells.

Nuevas formas para las columnas de hormigón

La exploración formal es un proceso de investigación mediante el diseño que considera sus propias condiciones para ampliar los resultados posibles. Este artículo presenta una estrategia de diseño paramétrico para columnas de hormigón ejecutadas con moldajes de telas, con el fin de apoyar el desarrollo creativo de esta técnica en composiciones arquitectónicas, promoviendo nuevas posibilidades tectónicas y espaciales. La estrategia desarrollada se basa en un sistema de encofrado compuesto de textiles con soportes verticales que generan columnas circulares, el cual se ha probado en modelos a escala y en elementos de tamaño real. El diseño paramétrico se establece a partir de una secuencia de círculos de radio y altura variable, además de un desplazamiento lateral que se define mediante un programa computacional que permite generar una variedad de diseños de columnas. La implementación paramétrica permite comprobar la versatilidad formal de estas capacidades constructivas, así como revisar condiciones de ejecución y estructura. Sugiere además nuevas posibilidades espaciales, de distribución, análisis y fabricación, evidenciando con ello la potencialidad arquitectónica del sistema digital y de los moldajes flexibles.

A Cable-Net and Fabric Formwork System for the Construction of Concrete Shells: Design, Fabrication and Construction of a Full Scale Prototype

This paper describes the construction of a thin-shell concrete roof with a novel cable-net and fabric formwork system. The system consists of a fabric shuttering installed on a cable-net structure, which is tensioned from stiff boundary beams supported by standard scaffolding props. The cable-net is made from 2015 uniquely sized cables and rods, connected by 953 steel nodes. A specific non-uniform distribution of prestress was computed, such that under the weight of the wet concrete the cable-net sags into the desired shape of the final concrete shell.All of the elements of the formwork system were digitally fabricated by specialised industry partners in Switzerland. After the installation of the boundary structure, the cable-net was tensioned with the prescribed non-uniform prestress. An on-site shape control system was used to minimise deviations between the as-built geometry and the digital model. Starting from the lower supports, the concrete was sprayed on the flexible formwork from two aerial platforms in a carefully planned sequence.The construction of the shell together with partners from industry was a proof-of-concept demonstration of the formwork system, showing that concrete shells with complex doubly curved geometry can be built efficiently and with minimal material waste in a real-world context.

Robotic variable fabric formwork

Abstract Casting is one of the most widely used construction techniques. Complex geometries produced via computational design processes are not readily achievable through traditional rigid formwork and are subject to increased material waste. More suitable casting techniques are required to represent digital design output efficiently. This article presents a variable fabric formwork developed to work in conjunction with a 6-axis robotic arm for casting doubly curved panels based on hyperbolic paraboloid geometry. The variable formwork is designed to be extendable in length and width so that it can produce a wide range of outcomes within a single formwork. The interface established in the workflow allows the physical formwork and digital design to influence each other. The article concludes by discussing a verification method used to confirm the accuracy of the outcome. This variable fabric form-work reduces construction waste and is a more sustainable method for casting complex geometries. Highlights Robotic arm used to manipulate a bespoke mould for fabric formwork casting. Constraints of mould design used to inform robotic arm of its fabrication limits. Workflow allows the physical formwork and digital design to influence each other. Verification of result reveals future area of research.

An experimental study on the lateral pressure in foam-filled wall panels with pneumatic formwork

Applications of structural wall panels using flexible formwork systems have recently attracted the attention of architects and engineers. Many of such panelised systems in the market are foam-filled walls, mainly presented in the form of sandwich panels. Knowledge of cast-in-situ induced lateral pressure on the formwork is critical for the economical and safe design of flexible formwork for construction. Formwork cost, on the other hand, comprises a high proportion of the total cost of a building constructed by cast-in-situ materials. Although extensive research has been conducted on the lateral pressure of concrete formwork, the components and mechanics of the lateral pressure in foam-filled walls have not been thoroughly understood. This paper will investigate the lateral deformation, and then lateral pressure on flexible fabric formwork used for construction of polyurethane foam-filled panels. From the lateral pressure on the formwork, the tension forces in the ties are calculated by measuring the compressive force developed between the formwork edges. The results are used for design of intermediate ties for controlling the lateral deformations in an innovative foam filled panelised system, which has been designed for rapid assembly of semi-permanent buildings for post disaster housing.

Active control of a rod-net formwork system prototype

Abstract A prototype rod-net for a fabric formwork system is described, including the fabrication, control of the geometry via turnbuckles, and the measurement of nodal co-ordinates via an image-based theodolite system. Such a net and fabric formwork system consists of a network of tie elements, either discrete or continuous, forming the main falsework structure, onto which is placed a fabric membrane acting as the flexible formwork for the pouring of wet concrete for the forming of a concrete shell. The fabrication of the plastic and steel net components of the prototype is described in detail, including the arrangement of the nodes, rods and boundary conditions. A control system was developed to determine the necessary adjustments at the boundary elements to move the rod-net to a target geometry to eliminate deviations that may arise from fabrication and construction tolerances. This control system showed that with minimal adjustments the rod-net could be directed effectively, resulting in deviations from the target surface reduced from up to 3–9 mm to below 1–2 mm for a 3D rod-net of approximate dimension 2.5 m × 4.5 m × 2.0 m. Additionally, the algorithm provided a more symmetric distribution of deviations around the target. The control system was coupled with 3D point-cloud measurements of markers placed on and around the rod-net by using a motorised image-assisted theodolite and specialised software for spherical and circular targets. This semi-automated process proved to be both efficient and accurate for determining the spatial co-ordinates of the markers and hence the node locations.

Development of an Innovative Modular Foam-Filled Panelized System for Rapidly Assembled Postdisaster Housing

In this paper, the development process of a deployable modular sandwich panelized system for rapid-assembly building construction is presented, and its structural performance under some different action effects is investigated. This system, which includes an innovative sandwich panel and its integrated connections, can be used as structural walls and floors in quickly-assembled postdisaster housing, as well as load-bearing panels for prefabricated modular construction and semipermanent buildings. Panels and connections are composed of a pneumatic fabric formwork, and two 3D high-density polyethylene (HDPE) sheets as the skins, filled with high-density rigid polyurethane (PU) foam as the core. HDPE sheets manufactured with a studded surface considerably enhance stress distribution, buckling performance, and delamination strength of the sandwich panel under various loading conditions. The load-carrying behavior of the system in accordance with some American Society for Testing and Materials (ASTM) standards is presented here. The results show the system satisfies the codes’ criteria regarding semipermanent housing.