Reliability test and analysis for a steel truss of coal conveying belt corridor
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A belt corridor of Pingdingshan tianan coal company was built in the 1980 s, after 30 years of use, lower chord and lower chord node of steel truss structure rust serious, bearing capacity of bar and node plate has not meet the design requirements, that being serious security hidden danger to producing activity. To assess the reliability of steel truss, according to the relevant national standard for test and calculation analysis, determine the level of reliability by test, and gives the conclusion and suggestion. Introduction A coal conveying belt corridor of Pingdingshan tianan coal company was built in the 1980s, this coal conveying belt corridor is large span, perennial work under dynamic load, bearing structure is steel truss system . But because of the bad use conditions of coal preparation plant, the corrosive medium is more, plus the improper maintenance during use, lower chord and lower chord node of steel truss structure rust serious, bearing capacity of bar and node plate has not meet the design requirements, that being serious security hidden danger to producing activity . To assess the reliability of steel truss, according to the relevant national standard for test and calculation analysis, determine the level of reliability by test, and gives the conclusion and suggestion. Engineering situation A coal conveying belt corridor of Pingdingshan tianan coal company, is located in the middle of pingdingshan mining area, structure form is the level of single span simply supported steel truss structure, with continuous belt transmission machine, length of 31.2 meters. Both ends of the belt corridor respectively is supported by concrete frame transfer station and concrete column bracket, belt corridor across coal railway of the first mine coal preparation plant. In the middle of belt corridor is coal conveying belt, two side of belt corridor is the pavement, belt corridor appearance and internal structure are shown in figure 1 and figure 2. Steel truss uses double angle and bar, is a simply-supported structure, one end is a rolling bearing, the other end is fixed International Conference on Energy and Environmental Protection (ICEEP 2016) © 2016. The authors Published by Atlantis Press 758 support. The belt corridor roof adopts the wooden board with light color steel plate, Wall adopts 20 mm thick wood panels and glass steel window with color steel plate, floor and roof plate adopts 200 (now C18) precast reinforced concrete tank plate. Using common carbon steel structure material A3 steel (now for Q235 steel), allowable stress is 1700kg/cm2, electrode uses T420 type electrode, steel structure with red lead render, and adopts grey ink for corrosion protection. The project was built in the 1980 s, since put into use has been more than thirty years history, due to the effect of mining area work climate and humid conditions, long-term adverse work environment, corrosion situation is increasingly serious, the structure safety is reduced. In order to ensure the safety of the whole production system of coal preparation plant, we test structure safety and reinforce steel truss of coal conveying belt corridor. Fig.1 The external structure of 901 belt corridor Fig.2 The internal structure of 901 belt corridor Steel truss bearing capacity calculation and rating Coal conveying belt corridor of the first mine is made of two same size steel truss, top chord adopts 2∟125×14 double angle bar, lower chord adopts 2∟110×8 double angle bar. Two steel truss structure is connected by level of support and beam, steel truss structure is parallel chord truss with herringbone diagonal and vertical bar, one end fixed hinge, the other end of the roll hinge, it can be simplified as a plane truss to calculate bearing capacity, calculation diagram and node number are shown in figure 3. S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 X2 X3 X4 X5 X6 X7 X8 X9 X10 X11 X12 X1 X13 Fig.3 The calculating diagram of steel truss