Grid Structure Design And Analysis Under Dynamic Wind And Machine Vibration Of Trestle In Cement Mill

Steel angle truss structure, steel tube truss structure and space truss structure havebeen widely used in trestle structures in cement mill. Trestles with a span of18m,30m and48m were designed in this paper, respectively by steel tube truss structureand space truss structure.With a large span and weak stiffness, the trestle structures are more sensitive towind induced vibration. However, in load code of China, there is no explicit provisionabout the calculation of gust effect coefficient for trestle structures. Therefore, it’snecessary to ascertain the guest effect coefficients for the trestle structures based onwind induced vibration analysis, which could also provide basis for the wind load. Inthis paper, the characteristics of the wind load were introduced. Time domain methodwas applied to researches on trestle structures with a different span (18m,30m and48m), with a different height above ground (5m,10m,15m,20m,30m), and withdifferent structure forms (steel tube truss structure and space truss structure) toascertain the guest effect coefficient. It was found out that the guest effect coefficientswere all between1.45and1.55under all different conditions. Ignoring different spans,heights above ground and structure forms, it was recommended that the guest effectcoefficient could be taken as1.55in a design.A strong vertical vibration of bridge deck in trestle structures has been a problem,which has even affected the normal use. Therefore, it’s necessary to analysis thedynamic effect of trestles under conveyor vibration. In this paper, the vibration sourceand vibration load were determined after analyzing the vibration reasons, namely aharmonic load caused by no coincidence of center point of mass and of shape.Researches were done to analysis dynamic response of trestle structures with differentspans under maximum harmonic load or single harmonic load, with the result ofdynamic magnification coefficient. To guarantee the safety of trestle structures inengineering applications, resonance may be avoided by reasonable choices of speed ofconveyor and span of trestles.