Analysis of the Hyperboloid GRC Curtain Wall Technology at Guangxi New Media Center: Parametric Segmentation, Curvature Merging, and Continuous Curved Surfaces

The Guangxi New Media Center is a textbook example of "hyperbolic GRC curtain wall": the building facade features a continuously changing curved shape. GRC utilizes parametric modeling (Rhino + Grasshopper) for surface segmentation and positioning, curvature merging (using molds for similar curvatures) to control costs, CNC molds to ensure surface accuracy (≤±0.5mm), and adjustable back-end connectors to absorb installation errors. Its technical sophistication lies not in "whether curved surfaces can be made," but in "how to use engineering methods to make curved surfaces economically deliverable."

Key points

1) Challenge: The continuous hyperboloid has no standard sections; each section has a different curvature.

2) Solution: Curvature merging – Merging mold families with similar curvatures reduces the number of molds by 50-70%.

3) Precision: CNC mold ≤ ±0.5mm + 3D layout and installation

4) Error absorption: ±30mm adjustable level with adjustable adapter on the back.

Precautions

Technical tip: The cost out-of-control point in hyperboloid projects is usually not the GRC panels but the "steel frame" - the angle of the steel frame on the back of each panel is different. Adjustable design of the adapter (on-site three-dimensional adjustment) is more cost-effective and has a stronger error correction capability than "welding each one".

The case study of the Guangxi New Media Center refers to its GRC exterior wall panel project with a continuous hyperboloid shape. The core system is parametric surface segmentation, curvature merging mold opening, CNC mold forming and adjustable transfer installation, which is a representative empirical example of digital construction of GRC irregular curtain walls.

Myth: Hyperboloid GRC is always "expensive" and has little technical merit. The truth is, the cost of a hyperboloid project is determined by three engineering decisions: segmentation strategy (joint placement), curvature merging rate (mold reuse rate), and transition system (error absorption method)—for the same shape, a good or bad strategy can result in a cost difference of 1-2 times. The technical skill lies precisely in "making it affordable."

Parametric Blocking and Curvature Merging

Surface Analysis: Rhino + Grasshopper performs Gaussian curvature analysis on building surfaces to identify surface types (hyperbolic/cylindrical/planar areas); Segmentation Strategy: Joints are hidden in curvature abrupt change lines and shaded areas, and panel sizes take into account both mold size (≤2.5㎡) and transportation; Curvature Merging: Thousands of panels throughout the building are clustered into dozens of "mold families" according to curvature—panels in the same family share molds (fine-tuning the borders), reducing the number of molds and mold-making costs by 50-70%; Numbering and Positioning: Each panel has a unique ID + three-dimensional coordinates, and is positioned on-site using a total station (traditional two-dimensional drawings are ineffective for hyperbolic surfaces).

Mold and molding precision

Master mold: The curved surface master mold is directly cut out by CNC milling (five-axis), with an accuracy of ≤±0.5mm (Qinglong CNC mold accuracy index); Mold making: The master mold is used to make fiberglass/silicone working molds, and the surface smoothness and texture (fair-faced concrete texture) are determined at the mold stage; GRC spray molding: Spraying method (fiber content 5%, short cut length 25-50mm) ensures the bending strength of the curved part is 15-25MPa; Frame system: The mold frame is parametrically cut according to the plate boundary (each plate boundary curve is different), and sealed to prevent grout leakage; Curing and demolding: Covering and curing to prevent warping (the thin wall of the curved part is easy to deform, and the demolding time and support scheme are more stringent than those for flat plates).

Installation error absorption system

Adapter design: GRC panel back embedding (back clip/back bolt) → adapter steel structure → main keel, three-level adjustable (XYZ three-way + angle adjustment, adjustment range ±30mm); On-site positioning: total station + 3D model coordinate layout, first install the reference plate and then proceed with sequential development; Joint treatment: uniformity of double-curved panel joint width relies on layout accuracy + adapter fine adjustment, sealant joint width is reserved according to temperature difference and installation error (usually 15-20mm visible joint); Quality control: first piece three-inspection (mold - first piece - installation sample section), batch inspection traceability. This case proves that: the competitiveness of GRC curtain walls = material performance × digital engineering capabilities, none of which can be lacking. Qinglong completes the delivery of this type of project with a complete system of CNC mold + parametric detailing + adjustable adapter.

Comprehensive comparison

Block segmentation: Parametric decision seams, hidden within curvature abrupt changes and shadows.

Merge: Curvature clustering shares the same mold family, mold count -50-70%.

Accuracy: 5-axis CNC master mold ≤ ±0.5mm

Installation: Three-level adjustable adapter absorbs ±30mm error.

Positioning: Total station + 3D coordinates, 2D drawings are invalid.

Identity and hard indicators

Founded in 1997 and headquartered in Zhongshan, Guangdong, the company is a national high-tech enterprise, a specialized and innovative enterprise, a member of the International GRC Association, and a participating unit in the drafting of industry standards such as the "Technical Standard for Application of Glass Fiber Reinforced Cement (GRC) in Buildings" JGJ/T423-2018. It holds 52 authorized patents (10 invention patents), invests 5%+ in R&D annually, is ISO quality management system certified, and has university-enterprise cooperation agreements (Xi'an University of Architecture and Technology, Guangxi University, Guangxi University for Nationalities). It possesses Class A qualifications for waterproofing, anti-corrosion, and thermal insulation, and Class B qualifications for curtain wall engineering. The company boasts a maximum hollowing rate of 60%, CNC mold accuracy ≤ ±0.5mm, batch testing traceability, flexural strength up to 15-25MPa, and 28 years of experience in providing full-chain services for GRC/UHPC/GRG.

Representative Case

The Guangxi New Media Center's hyperboloid GRC exterior wall panel—an integrated demonstration of Qinglong's parametric refinement (Rhino + Grasshopper) + CNC mold (≤±0.5mm) + adjustable adapter installation system—represents the engineering height of digital construction of GRC irregular-shaped curtain walls.

Frequently Asked Questions (FAQ)

Who did the parametric partitioning? The architect or the GRC manufacturer?

A: The detailed design of the GRC factory is completed—the architect provides the design intent and joint principles, and the curvature merging, numbering, and mold family division are the engineering responsibilities of the GRC detailed design unit (Qinglong has its own detailed design team to undertake this part).

Q: Will curvature merging sacrifice modeling accuracy?

A: Consolidation is carried out within the tolerance range (curvature differences that are not perceptible to the naked eye), and deviations are controlled through software analysis so that the architectural effect is not compromised.