DOME ROOF OF ABOVEGROUND STEEL TANK WITH V=70000 m 3 CAPACITY. Lyubomir A. Zdravkov 1

Transcription

1 DOME ROOF OF ABOVEGROUND STEEL TANK WITH V=70000 m 3 CAPACITY Lyubomir A. Zdrako 1 Abstract: Dome roos are the lightest structure to coer cylidrical taks. Whe they are steel made they could ot be used to coer serious spas, respectiely big taks. Author has checked the possibilities to use steel dome roo as coer o aboegroud cylidrical tak with V=70000 m 3 capacity ad diameter D=64 m. The iestigatio was made with appropriate 3D sotware. It is used oliear solutio, accoutig large displacemets o steel structure or more accuracy. Most serious problem is agueess o sow distributio ad combiatio o wid ad sow loads. Key words: dome roo, radial girders, load combiatios, oliear solutio Uder oe ad the same coditios o use it is possible to desig ad use dieret kid o roos spherical, coe shaped, sel-supportig or supported. The quatity o used material ad the price o acility are dieret or eery costructie solutio. Dome roos are the lightest steel ixed roos with girder s costructio. They ca be used whe the iteral pressure is higher, do ot hae problems with moutig o a iteral loatig roo. Supplemetary oudatios are ot ecessary or dome roos. I other words always whe it is possible the dome roos are recommeded. The limited use o dome roos ca be metioed as their disadatage. It is cosidered that they caot coer large diameters, i.e. to coer taks with big olume. Recetly the biggest taks with dome steel roo i Europe hae the olume o V = m 3. Durig his actiity as a desiger the author was requested to check the possibility weather the tak with capacity V = m 3 ca be coered with dome steel roo. The tak is or molasses storage ad will be costructed i Czech Republic. This task was a real challege. I the result is positie it would exteds boudaries o use o this type o roo. 1. Geeral geometrical tak s speciicatio: - diameter o the shell D = 64,0 m; - height o the shell H s =,0 m; - maximum illig leel o product H t = 1,5 m ; - omial olume o the tak V = m 3 ; - radius o the spherical dome R r = 80,0 m < R r,max = 1,5.D = 96,0 m; - highess o the roo = 6,68 m; - umber o the coerig shields / radial girders = 90 бр.. Pressure upo the spherical dome - sow S = 0,7 kn/m ; - oer pressure p 0 = 1, 0kPa ; - acuum p = 0,5kPa ; - maximum wid speed = 45 m/s ; The wid pressure must be calculated accordig to the ollowig: 1 Lyubomir Agelo Zdrako, PhD, ciil egieer, Adacta Project 006, Soia 1606, 4 Kame Adree str., loor 4, L_Zdrako@mail.orbitel.bg 1

2 (1) w = m = 16,6dN = 1,66kPa 16 () w = wm. kz. c = 1,0403kPa, where: k z = 1,37 is a coeiciet, related to the chage o the pressure accordig to heights; c = 0,6 coeiciet, related to the orm o surace. 3. The measuremet o the parts o the roo 3.1. Roo coer plates ) π. D Whe it is kow that the umber o the girders is = 90 L = =,34m, where L ) is a distace betwee the girders by shell circumerece. а) loadig combiatio or measuremet o the roo coer plates - loadig perpedicular to plates load combiatio rom the top to the bottom: (3) q 1 = gr.cosα + ψ.( S.cosα + p) - loadig - perpedicular to plates load combiatio rom the bottom to the top: ' (4) q = gr. cosα + ψ.( w + p0), where: gr = t r. ρ. γ = 0,006.78,5.1,1 = 0,518kN/m - desig loadig o sel weight o the roo plates, whe the thickess is t r = 6 mm; g load is aorable; ' ' r = t r. ρ. γ = 0,006.78,5.0,9 = 0,44kN/m S = S = 0,7.1,4 = 0,98kN/m - aorable loadig rom sow; p0 = p0 = 1,0.1, = 1,kN/m - desig loadig o iteral pressure; p = p = 0,5.1, = 0,6kN/m - desig loadig acuum; w = w = 1,0403.1,4 = 1,456kN/m - desig loadig o wid; - desig loadig o sel weight o the roo plates, whe the ψ = 0,8 - coeiciet o combiatio o two short term loads; α agle betwee the horizotal plai ad tagetial to the roo i the examied poit. Whe the coer plates is accepted as sigle spa girder or ertical loadig, the bedig momets i it is determied accordig to the ollowig : (5) 1 1 M...1,673., 1 = q1 L = = 1,01kNm 8 8 (6) 1 1 M...1,736., = q L = = 1,05kNm 8 8 The bedig momets i (5) ad (6) are determied or poit o plates betwee the shell ad the roo, where α = 3, The miimal thickess o the joit must be determied accordig to the: 6. M max 6.1,05 (7) tr = = 0,54cm γ. R 1.1,5 c y The thickess o the roo steel joit S35 is accepted i the ollowig order: - t r = 6 mm whe the distace betwee two eighborig radial girders L = 1,8, m; - t r = 5 mm whe the distace betwee two eighborig radial girders L 1,8 m.

3 3.. Roo costructio With appropriate program hae bee created 3D model o the roo s dome ad the last two courses o the shell (ig. 1). The top agle (TA), which has bee made rom a thick steel sheet i this case, is put o the place o joit betwee the roo ad the dome. The roo plates are coected to TA with uiterrupted joit. ig. 1 Computer model The sectios o the roo structure are examied whe the eorts i the elemets hae bee cotrolled, the p- Δ eects ad the geometrical ot liear behaior o the costructio hae bee take ito accout. The pressure is doe step by step ad eects o the preious loadigs are reported Desig o the dome roo i exploitatio coditio. The positio o the loadigs o the roo is still uclear matter. I Bulgaria stadards [] the way o distributio o the loads o the spherical domes is ot cosidered. The author has made supplemetary researches or suggestios or possible way o distributio i [1], [3], [4], [5], but there is little iormatio regardig this matter. Due to this reaso it was ecessary that the author improised ad relied o his sese o egieerig. а) combiatio o the loadig ad their distributio o the roo The schemes o the loadigs used or the research o the spherical dome are show o ig.. б) the ollowig sectios o the elemets o the roo costructio hae bee calculated: - radial girders IPE 0 accordig to the Euroorm rom steel S35; - TA thick sheet with dimesios 3х600 mm rom steel S35; 3

4 Loadig Combiatios: 1.) 1,1. G + 1,4. S + 0,8.(1,. p ).) 1,1. G + 1,4. S + 0,8.(1,. p ) 3.) 1,1. G + 1,4. S + 1,4. w 4.) 1,1. G + 1,4.(1,. S + 0,8. S) + 0,8.(1,. p ) 5.) 1,1. G + 1,4. S + 1,4. w 6.),9. G + 1,4. w + 0,8.(1,. p ) ) 0,9. + 1,. p G 0 ig. Loadig schemes Most importat load combiatios or desig o arious roo s elemets are as ollow: - or TA loadig 0,9. G + 1,4. w + 0,8.(1,. p ), which cause the pressure i the TA; - or the elemets i the radial girders the actual combiatios are dieret, depedig o the positio o the loads ad the costructio i pla but or the biggest part o them the most uaorable combiatio is 1,1. G + 1,4.(1,. S + 0,8. S ) + 0,8.(1,. p ) в) deormatio durig the exploitatio The delectio Z i the middle o the dome rom desig load combiatio: maxz = 3,49cm - whe the load combiatio is 1,1. G + 1,4. S + 0,8.(1,. p ) maxz = 1,91cm - whe the load combiatio is 0,9. G + 1,4. w + 0,8.(1,. p ) 3... Measuremet or roo structure or moutig coditio I order to acilitate the roo erectig works, roo elemets are grouped i shields. They are mouted o the bottom o the tak i the same time with the erectig o the irst courses o the shell. I order to ollow the desig geometry, a temporary supportig deice is put i the middle o the tak. It acilitates assemblig o the roo ad helps to reach desig shape. (ig. 3). ig. 3 Temporary support or roo assemblig 4

5 Ater the moutig o all roo shields o the bottom at their mutual welds are made, the tak will be illed with the water, ad as a result o it the roo will bega to loat. O its moig to top o the shell the roo is used as a moutig platorm. The loadigs upo the dieret shields durig the moutig ad assemblig o the roo o the bottom are: - dead weight o the costructio G ; - lie load o erectors ad equipmet Q = 0,5 kn/m. а) irst decisio o iteral supportig The roo s shields are attached to two supports (to the bottom ad o the supportig structure i the middle o the tak). The radial girders IPE 70 rom steel S35 match the requiremets or stregth, but ertical moemet is ery serious: L (8) max = 48cm < [ u ] = = 16cm 00 It is obligatory to use supplemetary supports durig the moutig o the roo. б) secod decisio o iteral supportig The roo s shields are supported o 3 poits (o the bottom, o the support i the middle ad o the supplemetary support) (ig. 4). ig. 4 Scheme o temporary supportig o roo shields o 3 poits Radial girders IPE 40 rom steel S35 match the requiremets or stregth. I this case the maximum o ertical moemet is max = 3,7 cm < [ u ] 4. Total weight o the roo costructio - radial girders IPE 40 accordig to Euroorm rom S kg; - TA sheet 3x600 mm rom S kg; - roo plates rom S35: t r = 6 mm kg; t r = 5 mm kg; - cetral rig o the roo rom S kg The total weight o the roo icludig weight o top agle is G r = 60995kg aerage metal quality or 1 m uit ca be calculated as: (9), = Gr g r m = = 81,13kg/m A 317 r. Usig this igure, the 5

6 5. Coclusios 5.1. Steel dome roos ca be used successully to coer taks with diameter o the shell D 64 m, e.g. capacity V m 3. Cosiderig the higher requiremets or decreasig o apor leaks i the atmosphere, this type o roos ca work uder icreased iteral pressure as well as with the mouted iteral loatig roo i the tak. So they are better solutio tha supported coe roos o the taks with big diameters. 5.. Very serious problem is the lack o iormatio about real distributio o sow load upo the roo ad the possibility or loadig o the roo rom sow ad wid i oe ad the same time For the dieret roo s elemets the most uaorable load combiatio is dieret. Ee or oe radial rib rom the dome the actual load combiatio chages or its legth. Usually or dome roos most uaorable are o symmetric loads i pla, which ca impose dome to lose stability. 5.4 Ote whe determiig the ecessary sectios o roo structure, the thig to be cosidered is the moutig coditio. Literature: 1. Инструкция за проектиране на СВЦР с обем от 100 до m 3 за системата на енергетиката, Енергопроект, Норми за натоварване и въздействия върху сгради и съоръжения, ДВ, бр. 9 от 004 г. 3. Рекомендации по определению снеговой нагрузки для некоторых типов покрыий, ЦНИИСК им. Кучеренко, Москва, 1983 г. 4. API Std 650, Welded Steel Taks or Oil Storage, Teth Editio, Addedum 1 4, December EN 14015:004, Speciicatio or the desig ad mauacture o site built, ertical, cylidrical, lat-bottomed, aboe groud, welded, steel taks or the storage o liquids at ambiet temperature ad aboe, Noember