Bracing

[Sgt Evans]

What type of bracing r u using???

[sciolyswizzle16]

would you guys suggest using both end joints and lap joints when bracing a tower?
for example, using end joints on the horizontal pieces connecting the top of the tower and the bottom of the tower then using lap joints for the rest of the bracing?

[12thomasal]

slm, If I tilt the chimney section, does that reduce the swaying factor

[SLM]

slm, If I tilt the chimney section, does that reduce the swaying factor

No. The compression force in the chimney increases as the tilt angle increases. The sidesway of the chimney frame is directly proportional to the intensity of the axial force in the compression members: the larger the force the more the frame would displace. So, tilting a chimney frame actually increases the sidesway of the frame.

However, (1) the sidesway is very small to begin with, so it should not be of a major concern for most tower, and (2) the tilt angle is very small (in our case about 4 degrees), so its impact on the behavior of the tower is insignificant.

[SLM]

would you guys suggest using both end joints and lap joints when bracing a tower?
for example, using end joints on the horizontal pieces connecting the top of the tower and the bottom of the tower then using lap joints for the rest of the bracing?

It can certainly be done that way. Although, you need to pay extra attention when constructing a butt joint; you need to make sure that either end of the horizontal piece is completely flat and parallel to the member it is being glued to (you want to avoid any gaps between the two pieces).

We've found that most of the time lap joints work very well even for horizontal pieces. They are easy to construct and, in most cases, their construction doesn't require a lot of precision.

[sciolyswizzle16]

thanks SLM, i definitely will consider that

[yousef213]

on the base of the tower, or any part really,, could you skip the horizontal pieces between the x bracings, or would that weaken it significantly?

[jander14indoor]

on the base of the tower, or any part really,, could you skip the horizontal pieces between the x bracings, or would that weaken it significantly?

Probably not, especially the bottom.
Key failure mode on bottom is legs spreading out (especially on a smooth surface, common in contest test setups), increasing bending load and causing premature failure or tip over. Need horizontal members around the bottom to constrain this.

Probably not on top either unless the angled pieces are fairly horzontal anyway. Again, you want to prevent the uprights from bowing out (or in) as well as sideways, and an occasional horizontal strip is an efficient way to do that.

Note, on SLM's diagrams above, the uprights without horizontal cross bars tend to bow out, those with tend to tilt.

Jeff Anderson
Livonia, MI

[deezee]

i didnt have horizontal bracing, and I did better than when I had efficiency of 21

[TYG]

i didnt have horizontal bracing, and I did better than when I had efficiency of 21

Was it able to hold all 15kg?