How to reinforce floor joists

[Fågelvägen]

Yep, to create tension, the floor structure should be arched in the middle and fixed at all ends. This is how it's done with bridges. When constructing a concrete bridge, pipes are cast in, and a number of stainless wires are placed inside these pipes. Once the bridge is finished, the wires are tensioned with hydraulics, causing the bridge to start going downward. The bridge's construction makes it want to lift, but it can’t, and the upward tension remains, allowing the bridge to withstand a high load without sagging. A bridge can start to fail if it begins to flex up and down, leading to micro cracks throughout the construction. It won't collapse immediately, but over the years, it loses its load-bearing capacity.

Reinforced
With plywood, completely ineffective
Doesn't work at all, when I lower the prop/jack, we're at the same levels with the same dip.

 

[jonaserik]

Is that what you've done, the reinforcement is only halfway, it must be in one piece throughout its entire length, now it is (tense) reinforce only up to the middle it seems like, a reinforcement must go between the supports, wall to wall to support. It's not possible to reinforce halfway on the joist.

 

[Fågelvägen]

Is that how you did it, the reinforcement is only on half, it must be in one piece its entire length, now it's (tense) reinforcing only up to the middle it looks like, a reinforcement must go between the supports, wall to wall to bear up. You can't reinforce halfway on the floor structure.

Hi
Yes, the plywood is 2500mm long, so if I splice the entire length of the beam, will it be better?

 

[jonaserik]

Yep, it's not possible to achieve stability with the reinforcement as you've done. When you add to the other end, you should place a one-meter piece over the joint, to have a continuous reinforcement all the way. Otherwise, the reinforcement may want to fold at the joint. Don't forget to tension it again, a few centimeters.

 

[Fågelvägen]

Yep, you can't achieve support with the reinforcement you've done. When you fill to the other end, you should place a piece of one meter over the joint, this is to get a whole reinforcement all the way. Otherwise, the reinforcement may want to bend at the joint. Don't forget to tension it again, by a few centimeters.

Hi
Installed a HEA beam and it turned out perfect.

 

[jonaserik]

Now it came. Not wrong to do so, then it becomes a carry on half the length and strengthens the entire joist. Good luck with the rest.

 

[Fågelvägen]

Now it came. Not wrong to do so, then it will be a support for half the length and strengthen the entire beam structure. Good luck with the rest.

Thanks
I do the same in more places, it will be perfect.

 

[jonaserik]

Between the beam and the joist, you can drive in wedges, a bit difficult to get a perfect fit, one from each side and lubricate the wedges with wood glue, then it won't squeak.

 

[claym]

Between the beam and the joists, you can wedge in shims—it's a bit difficult to get a perfect fit—one from each side and coat the shims with wood glue, then it can't creak.

Is the purpose of this to get the beam tight against the joists so that they don't sag down?

 

[jonaserik]

Is the purpose of this to get the beam tight against the joists so that they don't sag downwards?

Yep, and to get a rigid support on the floor structure, the wedges are tapped in so they just grip, not so that the floor structure lifts.