led sports flood lighting design and construction
1. Introduce
The sports park features a stadium and commercial facilities, constructed with a framework and steel structure. The eaves of the stadium reach a height of 35 meters, while the steel structure stands at 47 meters, exhibiting an elliptical form. The membrane structure is inspired by the concept of "flight," utilizing a combination of steel trusses, cables, and membranes to create a "double-wing" roof design that embodies a light and airborne architectural aesthetic, imparting a dynamic sense of movement to the stadium. The commercial facilities have an eaves height of 6 meters, a steel structure height of 20 meters, and a triangular configuration. A 50-meter span skybridge connects the stadium and the commercial facilities, unifying the two distinct structures.
2. Design Plan
The membrane structure of this project employs PTFE (polytetrafluoroethylene) material, which boasts high light transmittance (13% ± 3%). The light that permeates the membrane is naturally diffused, eliminating shadows and glare. Leveraging this characteristic, the flood lighting design incorporates high-power LED flood lights that project light from the interior to the exterior. The light disperses into the atmosphere through the membrane material. Additionally, a DMX512 controller is utilized to intelligently manage the LED flood lights, facilitating various color transitions for each scene, thereby creating a tangible and ethereal ambiance that dynamically reflects the stadium's theme of "double wings" unfurling and "flight."
2.1 Lighting layout
A gap exists between the membrane material and the supporting steel beams of the structure. Lighting fixtures can be installed on the steel beams and within the PTFE membrane. The areas are categorized based on the roof's shape and the arrangement of the steel structure grid. Following field tests, a lamp is positioned 1 meter apart in each designated area, with one area serving as a control subject. Between 12 to 22 sets of LED flood lights are allocated to each area, with the angle of the fixtures adjusted according to the inclination of the membrane structure in various sections to ensure uniform light distribution.
2.2 Lighting fixture Selection
To ensure effective illumination, high-brightness LED flood lights have been chosen, with 1.692 units designated for the stadium and 448 units for ancillary facilities. Based on the results of an on-site light transmission test, OSRAM's high-power SMD ultra-high brightness LED fixtures, each rated at 36 W (comprising 36 individual LEDs, with 12 red, 12 green, and 12 blue), have been selected. These fixtures are fitted with soft-focus tempered glass lenses that produce diffused light beams ranging from 30° to 60°. By overlapping multiple beams, a uniform lighting effect across the entire area is achieved.
The LED fixtures consist of multiple groups of light-emitting units paired with constant current LED drivers. Each fixture interfaces with the DMX512 controller via a PWM (pulse width modulation) signal interface, operating at TTL (transistor-transistor logic) levels. Each light-emitting unit incorporates several red, green, and blue LEDs, allowing for full-color variations through precise control of these units.
2.3 Control System Selection
The control system for this project is organized into three distinct control zones: the east side of the stadium, the west side of the stadium, and the commercial support facilities. A DMX512 controller is strategically positioned in each zone.
The system features straightforward wiring and ease of installation. The DMX512 controller translates the pre-configured lighting scene signals into PWM signals, connecting to each fixture via dedicated RS485 lines. This setup enables the LED fixtures to undergo various adjustments and dimming, facilitating a range of lighting effects. Each DMX512 controller can output two sets of international standard DMX512/1990 signals, managing a total of 1.024 dimming circuits (512 × 2). Additionally, the lighting scene control program can be stored on an MMC card (SD card) through a visualization program created on a computer. By accessing the MMC card's stored files via the on-site DMX512 controller, various media formats, including text, Flash animations, videos, and images, can be seamlessly integrated into landscape lighting displays, creating vibrant and dynamic visual effects.
3. Construction Plan
The LED flood light installation on the steel truss beam presents significant challenges for the construction process. A comprehensive and reliable construction strategy must be developed, taking into account the specific conditions at the site.
3.1 Construction Method
The stadium's roof structure is a cantilevered steel framework, reaching a maximum height of 45 meters above ground level. A narrow walkway traverses the center of the roof, limiting the routing of pipelines to this area. During the construction phase, the main conduit is initially installed on one side of the walkway, followed by the routing of steel pipes from the conduit to each circuit lamp. The wiring conduit is secured to the steel truss using clamps.
The commercial support roof structure is also a steel framework, with a maximum height of 15 meters and a minimum height of 6 meters. Due to the expansive area, erecting a scaffolding platform is impractical. Based on the site conditions, an electric lifting platform and localized scaffolding will be utilized for piping, threading, and lamp installation on the steel structure. Safety measures must be implemented throughout the construction process to ensure worker safety.
3.2 Lighting installation
In accordance with the design specifications and site conditions, the installation locations for the lamps are established, and the LED flood lights are affixed to the steel trusses. The lamps are secured using specialized support plates, which are attached to the trusses with clamps. These clamps must be custom-fabricated to accommodate varying truss diameters and must feature anti-slip mechanisms to ensure the lamps are securely fastened and resistant to wind effects.
3.3 Debugging
Once all power and communication lines are installed and the various pieces of equipment are connected, the debugging phase commences. The debugging process includes the following steps (specific procedures are omitted): inspection of lamp arrangements, line verification, group debugging, overall system testing, and performance evaluation. Programs will be written and comprehensive debugging will be conducted in accordance with the owner's specifications.