Membrane Structure Carport Drainage Design

 How to Design Effective Drainage for Membrane Structure Carports?

 Effective drainage design for membrane structure carports is crucial to prevent water accumulation on the roof, which can impact the quality and safety of the entire structure. Here, we discuss the design and methods for effective drainage in membrane structure carports.

 Drainage Design Approaches

 Membrane structure carports typically use either unorganized or organized drainage methods. Due to their unique and flexible design, it’s essential to consider the shape and effective drainage methods in tandem.

- Slope Requirements:  

  The drainage slope in membrane structures needs to be steeper than in conventional buildings. The slope for flat membranes should be between 15% and 20%, while the ridge height of double-curved membranes should exceed 10%. Additionally, the pre-tension of the membrane should be above 1.0 to 2.5 kN/m to prevent significant deformation under rain, which could cause water accumulation and sagging.

- Membrane Water Accumulation:  

  Water accumulation on membranes can lead to a cascading effect, where a small amount of water causes deformation, leading to more water pooling. Therefore, sufficient slope, refraction, and tension levels are essential to ensure smooth drainage. Integrating water guides, drainage ditches, and pipes with the membrane's structural design is recommended.

 Types of Drainage Systems

Organized and Unorganized Drainage Systems:

 - Large Public Membrane Structures (over 2500m²):  

  Organized drainage systems are recommended.

  - Small to Medium Open Membrane Structures (below 1000m²):  

  Unorganized drainage systems can be used.

  - Small to Medium Public Membrane Structures (1000m² to 2500m²):  

  Depending on the height, enclosed or open nature, appropriate drainage methods should be selected, potentially combining free drainage with organized drainage structures.

 Specific Drainage Methods

 1. Gutter Type Drainage Pipes:  

   These pipes are typically built as channels on the load-bearing beams of the carport. To maintain aesthetic appeal, they are often designed as embedded systems. It’s important to consider the direction and height of the drainage path and regularly check for blockages.

2. Pre-set Drainage Holes:  

   This method involves placing a drainage hole at the lower end of the membrane surface, allowing rainwater to exit through the hole. The location of these drainage holes must be strategically planned to avoid drainage issues.

3. Reverse Flow Drainage Systems:  

   This system installs a reverse flow drainage mechanism at critical points of the membrane structure, channeling rainwater into drainage channels and directing it to the ground. This method has the highest drainage efficiency compared to the other two.