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  1. molibden

    Norway bridge collapse

    Don't want to brag, but looks like I was right about block shear back in August :) No idea why Norwegian code didn't have this included...
  2. molibden

    Norway bridge collapse

    These failures are typical block shear failures. Timber failed in combination of shear and tension in these connections. Might not be the main reason but certainly something to look at.
  3. molibden

    Norway bridge collapse

    Splitting of the chord is a possibility, but I don't see it at this node. This node has light forces other than axial compression. That's why there are just a few dowels in the chord. Axial compression is taken by the chord which is continous. Diagonal on the other hand is loaded heavily in...
  4. molibden

    Norway bridge collapse

    Bolts are close together to reduce splitting of timber. If bolts are spread out, steel plates hold bolts rigidly and when timber shrinks or swells it causes cracks. Also you reduce rotational stiffness with bolts together. This makes me think.. with so much steel elements and rigid plates, is...
  5. molibden

    Norway bridge collapse

    I went to research a bit about Perkolo bridge collapse. It was due to design error, where they misread joint design force. Basically they designed one part of a joint for half the force they should. Scary. [link]https://www.slideshare.net/AdityaSanyal3/large-span-structuresnew]Starts at around...
  6. molibden

    Norway bridge collapse

    Here we go... As if we haven't seen steel or concrete bridges fail.
  7. molibden

    Norway bridge collapse

    This is bad for development of timber bridges. There is already a lot of scepticism. I work with timber a lot but I'm also nervous about rot when it comes to outdoor structures. Will be interesting to see the results of investigation.
  8. molibden

    Full Fixity Connections in Wood

    There are really stiff connections in wood. But you need bigger sections of members and appropriate connectors like long screws with full thread or glued in rods. You can make moderately stiff connections with bolts and steel plates but you also need bigger sections as normally and you need to...
  9. molibden

    horizontally discontinuous studded wood frame walls.

    What if such a wall has two perpendicular walls? If you connect horizontal plates to perp. walls, studs are basically prevented from buckling out of plane. I don't like it but in some cases I allow contractors to build walls on top of walls. If walls are braced at reasonable spacing.
  10. molibden

    Are these trends happening anywhere else?

    I was working in a small office with 5 engineers. It was very educating, I learned a lot. But it was also suffocating, constant pressure, working long hours and on weekends. I quit after 4 years and left proffesion for 2 years. I wanted to try again and started on my own. No way I was ever again...
  11. molibden

    What is reason for Top & Bottom Reinf. in simply supported covers

    You do kind of need top reinforement in the corners of the slab, if supports prevent movement (torsional moment m_xy).
  12. molibden

    Cantilever slab (blacony)

    Creep deflection with cracked concrete section will govern the design.
  13. molibden

    Cantilever slab (blacony)

    You can cover the bottom of the slab in a way it will look flat. Deflection is probably an issue. You can precamber formwork.
  14. molibden

    Untopped Hollowcore Diaphragm with Openings

    Why don't you do a FEM analysis of the floor and see how it behaves under in plane loads? It is same question with CLT floors or any other rigid prefab elements construction. You need to tie them together.
  15. molibden

    CLT stair flight connections?

    Option with steel elements. Can be done without steel, just self tapping screws with whole thread. Screws at an angle from both sides of the joint, CLT cut with small step joint for easier assembly.
  16. molibden

    Interior load bearing wall and fire design

    I got my answer. For future reference, the answer is that within fire compartment fire can spread everywhere. So you need to consider charring on all sides. Table below is in German but it is very helpful to understand the concept. This is probably the logic for almost all Europe.
  17. molibden

    Interior load bearing wall and fire design

    kostast88, fire engineer defines for how long does a structural element need to "hold" during fire (R30, R60, R90, R120min). Our job as structural engineers is to accomplish this using fire protection, structure itself or combination of both. For all materials there are calculation methods in...
  18. molibden

    Wind Load on a Building with a Soft Story

    Same problem with wind and seismic. Both are dynamic loads, but for simple stuff we use static loads for design. Soft story is an issue in both cases.
  19. molibden

    Interior load bearing wall and fire design

    I have load bearing interior CLT walls (or any other structural system, doesn't matter in this case) in multi-residential building. Each apartment is a fire compartment. Each apartment has several rooms as usual. My question is when to consider a wall with fire on both sides at once. For...
  20. molibden

    Ignoring Skewed Shearwalls and Designing as Cantilevered Diaphragm

    I would use equivalent length. With 5 degree skew this is the smallest simplification we do when we design. We don't really know the real loads or even real behavior of the timber frame, diaphragm... You have results without these walls. Now do another analysis with them and make engineering...

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