Detaljer om förslaget

1.1 Scope of EN 1993-4-2 (1) EN 1993-4-2 provides rules for structural design of vertical cylindrical, conical and pedestal above-ground steel tanks for the storage of liquid and liquified gas products. (2) EN 1993-4-2 is applicable to the design for resistance of cylindrical walls and flat bottoms constructed using unstiffened plates. The design of conical and dome roofs as shell structures (unsupported) or as supported on a structural framework (supported) are also covered. (3) EN 1993-4-2 is only applicable to the requirements for resistance and structural stability of steel tanks. (4) EN 1993-4-2 only covers steel tank structures in Tank Groups 1, 2 and 3, as defined in this document. NOTE Tank Group 4 is not defined in this standard (see 3.1.41). (5) This document is applicable to tanks within the following dimensional limits (see EN 1991-4): Tank aspect ratio hS/d < 10 Tank total height hS < 70 m Tank diameter d < 100 m (6) This standard includes suitable rules for the design of tanks intended to store solids suspended in a liquid, where the appropriate global density of the mixture is used. NOTE Tanks used for the separation of mineral particles of different density fall into this category. (7) EN 1993-4-2 does not apply to the following: a) tanks with gross capacity less than 5 m3 (5 000 l); b) dished-end tanks that have a diameter less than 5 m; c) tanks with characteristic internal pressures above the liquid surface greater than 50 kPa (500 mbar) (see pressure equipment directive); d) design metal temperatures outside the ranges defined in Clause 5, with −50 °C being the lowest temperature for the application of this document; e) tanks of rectangular and other non-circular planforms; f) tanks exposed to fire; g) floating roofs and floating covers; h) ancillary structures such as stairways, platforms, nozzles, piping and access doors. (8) This document does not cover a) the special requirements for seismic design of tanks, b) the design of a supporting structure, c) the design of ancillary structures such as stairways, platforms, pipe racks and ladders, d) the design of an aluminium roof structure on a steel tank, e) reinforced concrete foundations for steel tanks, f) the design of a conical hopper, g) the design of a transition junction between the base of a cylindrical shell wall and a conical hopper, h) the design of a supporting ring girder in an elevated tank. 1.2 Assumptions (1) Unless specifically stated, EN 1990, the EN 1991 series and the EN 1993-1 series apply. (2) The design methods given in this document apply if: - the execution quality is as specified in EN 1090-2, and - the construction materials and products used are as specified in the relevant parts of the EN 1993 series, or in the relevant material and product specifications. (3) This standard applies to axisymmetric structures, but includes the effects of unsymmetrical actions (e.g. wind), and unsymmetrically supported tanks (e.g. on discrete supports). (4) EN 1993-4-2 is intended to be used in conjunction with EN 1990, with EN 1991-4, with the other Parts of EN 1991, with EN 1993-1-6 and EN 1993-4-1, with the other Parts of EN 1993, with EN 1992 and with the other Parts of EN 1994 to EN 1999 relevant to the design of tanks. Matters that are already covered in those documents are not repeated. (5) Numerical values for partial factors and other reliability parameters are recommended as basic values that provide an acceptable level of reliability. They have been selected assuming that an appropriate level of workmanship and quality management applies.