Dear All,
I have question to section 8 of EN 1993-1-9. There is condition for stress range not to exceed 1,5fy and 1,5fy/(3)^0,5 (direct and shear stress respectively). Some times ago I read that if this condition is fullfilled then low cycle fatigue will not occur. I don't rememeber where I...
I am interested in how to apply wind action at duct bend (see green colour in attachment). In case of straight duct line I use "Pressure distribution of circular cylinders" according to EN 1991-1-4 from section 7.9. You can see also this pressure distribution in attachment (section A-A).
I do...
Yes, gravity center is usually misaligned (not central to the supporting rods). I just try to write down relations (equations) to describe such kind of structures looking at VBA code.
Rb1957 - looking at matrix methods it seems to be Direct Stiffness method used, but I am not sure yet. I must look at it more precisely. There is tension rod stiffness EA/L used like in VBA.
Handleman, Greg, IDS we can assume that this is a stiff box suspended into rods. When I showed VBA code maybe it will be better to look at it as a 3-D problem.
Rb1957 - I also tried to relate it with known equation sigma=FL/EA, but looking at units at both sides of equation F11 seems to be a...
Wires (rods) are vertically oriented (red colour). Suspended element is a rectangle (black colour). The pictures above are 2-D simplification. In reality it is 3-d problem with many rods. Below is 3-d sketch - maybe now it will be more clear. If You have any questions don't hesitate to ask...
Some description more:
Trying describe F11, F12 and F13 generally, it looks like below:
F11:
M*L/EA = x1^2+x2^2+x3^2... ; M is instead of F11. F11 seems to be Moment.
F12:
M*L/EA = x1y1+x2y2+x3y3... ; M is instead of F12. F12 seems to be Moment.
F13:
F*L/EA = x ; F...
I must change picture when we consider code above.http://files.engineering.com/getfile.aspx?folder=dc7d25b2-4142-43e2-a918-fb7cd432ce1f&file=Mass_hanging_rev_0.png
Hangleman - it can be something in this direction You described. Rb1957 - it is 3-dimensional subject. There is no vibration or other dynamic interactions. There are many rods about 20, 30, 40 rods - it depends from the element. These are boiler Power Station suspended elements. It is very...
I am looking for equation describing situation like on the picture. It should be equilibrium equation using Rod Length and Rod Young modulus and concerns gravity center.
The problem is that I have ready quite long Visual Basic code made by other author but I cannot understand it. Let's start my...
I calculate seismic guide of the structure. This guide is in high temperature, i.e. in creeping area. Lets assume that creep strength (1%) is 100MPa. During normal work, stress are below this 100MPa value. When
seismic appears I have some stress concentration above creep strength. The question...
I got ANSI/AISC 360-05 Specification for Structural Steel Buildings. I didn't find answer what is allowable stress.
OK, maybe auxiliary question, which help focus on the point of subject:
In attachment there is a screenshot from book "The structural design of air ducts and gas ducts" (5.1.1...
This is ash hopper in power plant. The same problem seems to be clear for me using ASD. I would like to focus here on LRFD method with load combinations above.
http://files.engineering.com/getfile.aspx?folder=1e5ed1c7-0e4f-4aef-aad3-0eb842a4665c&file=Ash_hopper.png
Below notice can be helpful:
Acc. to ASCE7-10, C2.3.5 for self-straining loads below combinations should be used:
1.2D + 1.2T + 0.5L
1.2D + 1.6L + 1.0T
It seems to be LRFD. LRFD use force and moments capacity. How to relate it to my spatial stress state? How to calculate design strength?
I use Ansys and I have similar problem. I must set small tangent modulus 1, because many headers often cannot reach convergence. When 1 is applied then calculations converge very fast. It seems to be then artificial numerical problem. There will be rather no failure in reality.
