Design Points of Spherical Shell Space Frame in Dome Coal Storage

1. Project overview
A power company (Tangshan) Phase II 2×1000MW coal-fired power generating unit project dome coal storage space frame project, the inner wall diameter of the two domes closed coal yard coal retaining walls: 100m, the circular closed coal yard below the 17.50m elevation is the steel bar Concrete coal retaining wall, the elevation of the hemispherical space frame support is set to 20.00m, the diameter of the centerline of the space frame support is 106m, and a ring steel maintenance platform (attached to the ground) is set at an elevation of 17.50m above the circular closed coal yard. There are railings that meet safety standards), the inner diameter of the maintenance platform is initially set to 51.50m, and the width is 1m; and the escalator (no climbing ladder) and 3 climbing ladders (along with the space frame) lead to the coal transport trestle leading to the maintenance platform and the ventilation hall are set up. Concrete structure platform set on top of the reinforced concrete retaining wall at 17.50m elevation;

2. Spherical shell structure selection of dome coal storage shed

The dome space frame is generally in the form of a double-layer spherical shell, and the double-layer dome space frame can be divided into a cross truss system and a pyramid system. Among them, the pyramid system also includes rib-ring type quadrangular pyramid spherical mesh frame, joint square quadrangular pyramid spherical mesh frame, joint square triangular pyramid spherical mesh frame, and flat plate combined spherical mesh frame, etc. The rib-ring type quadrangular pyramid spherical space frame is the most commonly used double-layer spherical shell form in the coal storage structure. It arranges the upper and lower chord layers in a rib ring type. Each node has 8 rods, and the structure is relatively simple. This form requires “shrinking”. From the support to the top of the space frame decreases in sequence in the form of “two to one” or “three to two”. A process is generally more convenient to operate in SFCAD. The outline of the space frame should be fully considered and meet the operating conditions of the free rotation of the stacker and reclaimer. Generally, three-center spherical shells and round spherical shells are more commonly used.

The sag height of the space frame mainly depends on the height of the stacker and reclaimer. The sag height can be 1/3~1/7 of the span (plane diameter), and the ground support along the periphery can be relaxed to 3/4. The thickness of the double-layer spherical space frame can be 1/30~1/60 of the span (plane diameter). The space frame division of the space frame also has a very important impact on the economy of the space frame. According to past experience, the space frame size is mostly selected from 3m to 4.5m. Within this reasonable range, the larger the space frame, the more economical It is better; considering the equipment reasons, this project adopts the three-centered circular rib ring-type quadrangular pyramid spherical space frame, the span (plane diameter) is 106m, the vector height is 32.5m, and the thickness is estimated to be 3m. The square pyramid spherical space frame structure is adopted, and the projected area of the space frame is about 8824.7m2. The nodes are connected by bolt ball joints, and the space frame support method adopts the point support of the lower chord column. There are 36 supports, that is, one support for every 10°. The supports are set as constraints along with the tangential and radial directions, and the normal elastic release.