1 project overview
A project consists of two 27-story office buildings and a three-story podium. The structure is the main building frame-tube structure and the auxiliary building frame-shear wall structure. The relative height of the main building is 103.85m, the relative height of the annex building is 102.60m, and the relative height of the annex building is13.90m..
The roof frames of the main building and the auxiliary building are composed of frame columns and two frame beams, and the overall external wall decoration adopts the combination of glass curtain wall and stone curtain wall.
2 basket selection
Considering that the frames of the main building and the auxiliary building are relatively high from the roof, if the hanging basket suspension mechanism is put aside directly from the roof, the curtain wall construction of the upper frame cannot be carried out; If the hanging basket suspension mechanism is set with steel pipe bent, the steel pipe bent needs to be set in full house, which not only affects the roof construction, but also wastes a lot of manpower and material resources and has poor economy.
According to the analysis, the front bracket of the conventional hanging basket mechanism rests on the concrete structure, and the rear bracket is fixed by applying counterweight (see figure 1), but it is difficult to install the rear bracket and apply counterweight on a relatively high concrete roof truss. Finally, a new hanging basket is adopted by improving the hanging basket mechanism (see Figure 2).
According to different roofs, 36 hanging baskets are used in the curtain wall construction of the main building and the auxiliary building, and 8 conventional hanging baskets are used in the curtain wall construction of the podium.
3 hanging basket installation with beam riding code
The suspension mechanism of cross-beam hanging basket consists of telescopic beam, vertical clamping beam, diagonal bracing beam, upper pillar, rope guide block, reinforcing wire rope, unloading wire rope and rigging thread. , as shown in Figure 3.
3. 1 Erection of portal scaffold
In order to install the hanging basket on the top frame beam of the roof frame, a portal scaffold is erected on the roof as an operating platform (see Figure 4).
3.2 shelve the riding beam code
The two vertical clamping beams of the riding beam yard are directly sleeved on the frame beam of the roof frame, and the screws on both sides must be clamped firmly on the side wall of the frame beam, so that they can not swing firmly after installation (see Figure 5).
3.3 Strengthen the installation of wire rope
The pick-out length of the beam riding code is generally controlled at 1. 1 ~ 1.3m to prevent the pipe beam from being excessively deformed in cantilever state. The middle upper column is used as the pulling point of reinforcing steel wire rope to share part of the end load, so that the two outer ends of the riding beam code are fixed on the frame beam of the roof frame with steel wire rope and rigging screws.
3.4 The power wire rope is connected with the frame beam.
Power wire rope includes working wire rope and safety wire rope. The two ropes respectively pass through the rope guide blocks at the inner end of the riding car yard and are fixed on the frame beam of the lower roof frame, and the basket body at the other end hangs down.
3.5 Unloading wire rope is connected with the frame beam.
Considering that the safety of aerial work is very important, a steel wire rope is added at the tail of the beam-riding vehicle, which is connected with the girder for unloading as a safety reserve.
4 hanging basket hanging span safety checking calculation
4. 1 Checking calculation of hanging basket suspension mechanism
3D3S structural analysis software and large-scale general finite element software ANSYS are used for modeling and checking respectively, and the strength of beam riding code members meets the requirements.
4.2 roof frame beam structure bearing review
The load acting on the roof frame beam by the hanging basket suspension mechanism is provided to the design institute, which will check whether the strength and deformation of the frame beam meet the requirements.
By checking the safety of the component itself and the frame beam, it is proved that the hanging basket with beam riding code is guaranteed in theory and is convenient to be put into practical construction more safely.
5 matters needing attention in construction
5. 1 wire rope protection
Because the steel wire rope needs to be connected with the frame beam, and the joints are all hard-cut corners, considering the wear of the steel wire rope, rubber sleeves are used to protect the hard-cut corners during construction.
5.2 Wire rope end fixing
During installation, both ends of the steel wire rope are fixed by three rope clamps. The clamp seat of the rope clamp is buckled on the working section of the wire rope, and the snap ring is buckled on the tail section of the wire rope. At the same time, the rope clamps shall not be staggered on the wire rope (see Figure 6), where the rope clamp spacing is a = 6d ~ 7d, and d is the diameter of the wire rope.
5.3 Wire rope is connected with the frame beam.
Because the load of the hanging basket is finally bound by the wire rope and the frame beam as the binding end, it is necessary to ensure that the binding end is firmly bound in the construction process to prevent looseness or fracture, which will affect the operation safety of the curtain wall.
6 conclusion
The suspension mechanism of cross-beam hanging basket is very different from that of traditional hanging basket. The former has a simple hanging bracket structure, which is mainly composed of square pipe beams, upper columns and steel ropes, and does not need brackets and their fixing structures. It is very suitable for the construction of multi-channel roof frame curtain wall, and has the advantages of quick manufacture, convenient installation and cost saving.
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