New buildings start - cranes is on bottom floor - two weeks later 5 floors are finished and crane is still on top - HOW DO THEY DO THAT ?
203627
The crane is first assembled using a portable crane. Then sections are added to it using a device called a top climber. Basically they detach the top while keeping it balanced on the tower, jack it up 20 feet, insert a new section of tower using the detached but still balanced crane itself (yikes!), and re-attach the crane to the new top.
327604
A PBS video of the WTC construction using self-jacking cranes is shown at the ref. 1 site. This is part of the transcript:\nIn August, 1968 actual steel construction began. Kangaroo cranes imported from Australia were used for the first time in the United States. The cranes were assembled on top of the core columns. Each could lift 60 tons at a time. They would be the driving force behind the towers' construction. The cranes had the ability to jack themselves up 36 feet at a jump. As the walls grew to the height of a crane, the crane would hoist itself up, a neighboring crane would swing core columns into place beneath it, and construction would continue.\nAlso check out ref. 2 for some useful diagrams.
623858
What sort of time frame did you have in mind?  I'd like to know because I'd better be moving to higher ground.  \n\nUsually I don't bother with this sort of thing, but the recent hurricane season has got me thinking that something is up.  \n\nThanks for the warning! \n\nCheers!
25485
They probably pump it up and fill it. Lke allwater towers there are pipes going both up and down. Once filled though, they can leave it alone for awhile. Usually there are sensers inside that relay to a computer and alerts when the tower is getting low. In small towns I know sometimes they put too much water in and it isn't used. Thats why they sometimes flush it. But I would research the topic in an online enclycopedia.
187263
The swl of the crane is  14T so you need 2 crane (combines lift 2 x14T =28T,\nThe 40' container 1s 25T.\nYou need 2 crane operators to work in tandem to safety execute the operation.\nYour crane operators are competent to carry out the job and you do not mess up with them cause you do not have adequate knowledge on lifting
413344
they don't stand - they're bridges...  they're held up by the giant pillars that support each length of bridge, the pillars go all the way to the ocean bottom
235871
it's a very tall building and has a counterweight for when it gets windy
390707
h = -16x² + 48x + 8\n\nNow clearly it is projected from an elevated position and that position is 8 ft above the horizontal ( when x = 0 h = 8)\n\nSo the NEXT time it reaches 8 ft will be the second time it is there (on the way down)\n\n8 = -16x² + 48x + 8\nie 0 = -16x² + 48x\n= 16x(3 - x)\nSo x = 0 or 3\n\nThus the next time it reaches 8 ft is in 3 second
283981
That the crane should lift, at the most, this weight.\n\nIf it lifts beyond its capacity, there could be a catastophic failure.
159209
There is some disagreement as to what definition should be give for tallest.  Should it be the highest occupable floor? Should antennas be included? etc.  The Council on Tall Buildings and Urban Habitat defined four categories in which the "world's tallest building" can be measured:\n\n   1. Height to the structural or architectural top (including spires and pinnacles, but not antennas, masts or flagpoles)\n   2. Height to the highest occupied floor\n   3. Height to the top of the roof\n   4. Height to the top of antenna\n\nThe current record holders in each category is as follows:\n\nTaipei 101 leads in the first category with 508 m (1,667 ft); in the second category with an occupied floor at 438 m (1,437 ft); and in the third category with 448 m (1,470 ft).\n\nThe Sears Tower leads in the fourth category with 527 m (1,730 ft).
282043
I doubt that a "planning board" would likely follow or be much swayed by your calculations of barycenter, especially since they use the generalization "most" which is anything over 50%.  Perhaps you can concentrate each geometric building at its vertical centerline (center of square(s) and rectangle(s), circle(s), etc.  Then assign a "mass" to each "vertical point" on a ground plan.  Does "most" refer to building volume or mass?  Likely volume which you can scale from 3-D?\n\nDraw two lines (north-south and east-west) through approx. center oof plan.  Fix one end of the first line (north-south?) and assume the buildings rotate about the fixed point (with the plan held in a vertical plane and the N-S line horizontal).  Multiply each building "mass" times the distance to the fixed point (in feet) to obtain all the "moments" about the point.  Find the balancing moment in the opposite direction (a single force for the combined mass of buildings times a distance "x").  Repeat the process with the E-W line horizontal to find "y".  The barycenter should be at the intersection of the balancing moments ("x" and "y").\n\nRepeat the process with the new buildings included.  Compare the pre- and post-building project barycenters.  Good luck.
355096
To add a second floor you just build right on top of the first floor.\n\nYou follow the same procedure to add a room to your house...\n\nOn the left hand side of the window click the link for Downtown\n\nClick on Peterson's Hardware and Construction\n\nClick on the Add a Room button (top center)\n\nYour home floor plan will be displayed as a grid. Select the square on which you wish to build. To build a second floor you must select one of the 9 "inner" squares".  Choose the type of room and the name and click the Build button.\n\nYou should be aware - once you build a second floor you cannot destroy any rooms that lie below where you've build on the 2nd floor, unless you want to destroy the room on the 2nd floor as well.
89185
Well it's where work stops AFTER.......it is finished!!\n\nThe bus doesn't stop until it's there.\nThe train doesn't stop until it has arrived.\n\nYour work can't stop until it's complete! \n\nhahaha.....you can't get out of your work THAT easy bub!! ;)
198058
you have your units wrong, do you mean 5m/s or 5m/s^2 and you mean 20m from the ground?\nIf acc=5 when height=20 speed= 14.14 in upwards direction (using 2ax=v^2-u^2)\nIf initial speed is therefore -14.14m/s then at t=1 speed=-4.34m/s so it is still going upwards\nt=2 speed= 5.45m/s it is now going down. Both last results worked out using v=u + at\n(Sorry I assumed you meant 5m/s^2 straight up, you need the angle at which it accelerates aswell)
91784
The concrete blocks you saw at the end were counterweights.  Without the counterweights the crane would fall over or just be unable to lift anything that amounted to anything.  A crane's capacity lowers as the weight of what it is lifting moves farther from the counterweight.  A crane might have a 20 ton capacity if it's boomed all the way up or if the load is as far in as it will come but it won't be able to lift that same load farther out (the working radius).\n\nAlso there are a couple of systems by which the crane can lift itself higher.  One is where they have hydraulic lifts and will lift itself up and insert a new section.  The other is where the crane is actually attached to the building and does something similar.
463487
first the inside control is put into place...then the first section of the outside is built...then, they use side jacks to lift the inside up to the next level, and so on til they reach their height goal..
221849
You will get 3 different answers until you specify which surface of each brick contacts the one above/below.  The answer comes out of the equation for the pressure each brick adds to the pile. (P=F/A)  Don't forget the lowest brick; it's own weight will cause the bottom of it to be under more pressure than the top!