Equilibrium problem with a building: I can't figure it out

In summary, the question is asking for the torque of a 50-story building being planned, given its dimensions, mass, and wind force. The building is not anchored in bedrock and the total force of the wind is assumed to act at the midpoint of the building's face. The answer listed in the book is +2.3X10^9 and it is determined that the building will not topple. The person asking the question is unsure of how to calculate the torque and has attempted to use the torque equation but is stuck. The expert suggests calculating the torque about the lower corner where the wind force is applied, as any point can be used to calculate the torque as long as it adds up to zero.
  • #1
SalamanderGod
7
0
How should I be going about this problem? Here is the question, diagram, and my work:
A 50-story building is being planned. It is to be 200m high with a base 40m by 70m. Its total mass will be about 1.8X10^7 kg and its weight therefore about 1.8X10^8 N. Suppose a 200km/h wind exerts a force of 950 N/m^2 over the 70m wide face (fig. 9-73). Calculate the torque about the potential pivot point, the rear edge of the building (Where FE acts in fig. 9-73), and determine whether the building will topple. Assume the total force of the wind acts at the midpoint of the building's face, and that the building is not anchored in bedrock.
http://img158.imageshack.us/my.php?image=fig973ed8.png Fig 9-73
-The answer listed in the book is +2.3X10^9, and that it doesn't topple-
I do not know how to go about this problem, because it asks for the torque yet I am not sure how to get it without messing it up... I tried the torque equation along the x-axis and got:
sum of torque = 0 = -20FEx - 20(66500N(FA))
so -20FEx = 20(66500)
or FEx = -66500N
This is not the torque, I know, but I don't know what to do with this force and am kind of stuck in a rut...
 
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  • #2
Calculate the torque about the lower corner where FE is applied. You know the forces and torques must add to zero if the building is not moving, so you can use any point to calculate the torque, but that lower corner is an easy place to do it.
 
  • #3
ok, I'll try it.
 

Related to Equilibrium problem with a building: I can't figure it out

1. What is an equilibrium problem with a building?

An equilibrium problem with a building refers to a situation where the forces acting on a building are not balanced, causing the building to be unstable and potentially collapse.

2. How can I tell if a building is experiencing an equilibrium problem?

Signs of an equilibrium problem in a building may include cracks in the walls or foundation, leaning or shifting of the building, or uneven floors. If you notice any of these signs, it is important to seek professional help immediately.

3. What causes an equilibrium problem in a building?

An equilibrium problem in a building can be caused by a variety of factors, including structural defects, uneven settling of the foundation, or external forces such as earthquakes or strong winds.

4. Can an equilibrium problem with a building be fixed?

Yes, an equilibrium problem with a building can be fixed. However, the solution will depend on the specific cause of the problem. It is important to consult with a structural engineer or building professional to determine the best course of action.

5. How can I prevent an equilibrium problem from occurring in my building?

Regular maintenance and inspections of the building's structure and foundation can help prevent an equilibrium problem from occurring. It is also important to address any structural issues as soon as they are identified to avoid them from becoming larger problems.

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