| Concrete poles are widely used in overhead transmission line, broadcasting, post, communication and lighting line, and especially the ones used in overhead transmission line are of importance, because they are concerned with the safety of the whole line and the people. With the rapid development of electric power construction in our country, ultra-high pressure transmission lines like 110kV, 220kV, 500kV are popularized, and as a result, the pole is inclined to high grade and large figuration. Recent years, the requirements of strengthening protection of farmland and environment are also come up with by the government, so further the ultra-long assembled pole without guys is demanded more and more. Thus the pole must be safer, more suitable and more durable. But the ordinary concrete pole is apt to crack, under operation load the crack is wide, and the deflection performance is also bad, so much that it is difficult to apply to the current development trend. In terms of steel fiber's improvement and adjustment to inside structure of concrete and excellent characteristics of enhancement to cracking strength, capacity and toughness, since 2002, the seminar has started to do some research work on large-scale environment-protective steel fiber reinforced concrete pole without guys. In the fist stage, experimental studies on steel fiber distribution regularity and mechanical performance of steel fiber reinforced concrete fabricated by centrifugal shaping method are finished in succession. Based on previous work, this paper has mainly done the following several tasks and made serial achievements:1. Summarize the fabrication process of the steel fiber reinforced concrete pole, including choosing of raw materials, making of steel bar skeleton, achieving of prestress technique, centrifugal shaping method and atmospheric steam curing method. Combined with fabrication practice of annular section specimen and steel fiber reinforced concrete pole in tests, the basic requirements and precautions of every link are pointed out, and particularly the special demands of centrifugal shaping method are emphasized. All of these play a guiding role for standardizing the fabrication of the steel fiber reinforced concrete pole.2. Based on previous experimental study of material performance, study systematically the mechanical behavior of the steel fiber reinforced concrete scattered poles (the steel fiber reinforced concrete tapered pole and equal-diameter pole and the prestressed steel fiber reinforced concrete tapered pole and equal-diameter pole), mainly including cracking strength, crack distribution and its width, deflection and ultimate bearing capacity. It is proved that mixed with proper amount of steel fiber, the cracking strength is increased distinctly, the cracks at some sections become the distribution state which is short,thin and unlinked up, the crack width is decreased distinctly, the deflection performance is improved obviously, the ultimate bearing capacity is increased to some extent, and the ductile failure property is enhanced. All of these show the steel fiber's improvement to mechanical behavior (especially in crack and deflection) of the concrete pole is obvious.3. Based on"Technical regulation of design for tower and pole structures of overhead transmission line"(DL/T5154-2002) and"Technical specification for fiber reinforced concrete structures"(CECS38:2004), derive the design calculation method of the steel fiber reinforced concrete scattered pole in bending, including ultimate bearing capacity and serviceability limited state. Comparing the design calculation with the test result, it is showed that the design calculation method is appropriate and can be used for the practical project design.4. According to the characteristics of LuoHe~HuaiYang 220kV transmission line project and combined with previous experimental studies of material performance and mechanical behavior and design calculation method of the scattered pole, work out large-scale prestressed steel fiber reinforced concrete one-crossing braced portal pole without guys, and choose one with the height of conductor above ground being 27m to try. By the test, it is proved that under every load case, the mechanical behavior of the corresponding members of the pole meets with design requirements, the pole shows good integrity, and especially, the pole body is reinforced by both prestress and steel fiber, which improves safety and durability of the pole greatly. At the same time, by the test, some faults existing in design and fabricating are found out in time, and some feasible suggestions are come up with. All of this can be used as basis of construction of LuoHe~HuaiYang 220kV transmission line project which plans to adopt this new type of pole. 5. It is showed, by the contrast between the test and the design calculation of the pole body of large-scale prestressed steel fiber reinforced concrete one-crossing braced portal pole without guys, that using the design calculation method of the steel fiber reinforced concrete scattered pole for the design of the assembled pole is appropriate and safe. Combined with the test result of the single pole (the assembled pole with the height of conductor above ground being 27m), the calculating formula of deflection of the assembled pole is derived, and it is also appropriate and can be used for the practical project design.6. Summarize the engineering application of large-scale prestressed steel fiber reinforced concrete one-crossing braced portal pole without guys, mainly introduce its assembly and erection process, and relying on LuoHe~HuaiYang 220kV transmission line project, do some technology and economy evaluation. This type of pole is wholly erected by herringbone gin pole and this kind of erection method is convenient, safe and rapid. By the comparison of this type of pole and the reinforced concrete pole with guys and some towers, it is found that replacing the reinforced concrete pole with guys and some towers by this type of pole can achieve some technological, economic and social benefit.
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