Hello,
We are going to demolish and replace a load-bearing wall (4 meters on the ground floor in a 1 1/2 story house) and have received calculations and construction drawings from a qualified architect and engineer on how this should be done. After discussing several solutions back and forth, we decided to install an HEA 180 steel beam on 115x115 glulam columns - all specified in the attached drawings and calculations. However, the problem is that the 115x115 column, which is supposed to be hidden in the walls, is slightly too large and will protrude a few centimeters from the wall inside the house.
Since I don’t understand loading/strength calculations, I’m wondering if, based on these calculations, we could manage with a smaller dimension column or alternatively a glulam column with the dimensions 90x120, if such exist. Another option would be to place a steel tube in one of the walls (which is smaller than 115x115 and can handle a lot of load) and then place a glulam column in the outer wall which is to stand on the sill (a steel tube does not work there). But then the question is whether it is permitted to have glulam as a column on one side and a steel tube as a column on the other side....
We are going to demolish and replace a load-bearing wall (4 meters on the ground floor in a 1 1/2 story house) and have received calculations and construction drawings from a qualified architect and engineer on how this should be done. After discussing several solutions back and forth, we decided to install an HEA 180 steel beam on 115x115 glulam columns - all specified in the attached drawings and calculations. However, the problem is that the 115x115 column, which is supposed to be hidden in the walls, is slightly too large and will protrude a few centimeters from the wall inside the house.
Since I don’t understand loading/strength calculations, I’m wondering if, based on these calculations, we could manage with a smaller dimension column or alternatively a glulam column with the dimensions 90x120, if such exist. Another option would be to place a steel tube in one of the walls (which is smaller than 115x115 and can handle a lot of load) and then place a glulam column in the outer wall which is to stand on the sill (a steel tube does not work there). But then the question is whether it is permitted to have glulam as a column on one side and a steel tube as a column on the other side....
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you have 90x115 but I wouldn't use that there as it's calculated that the minimum should be 115x115. Instead, use structural tube 90*6 "inside" the house to handle those loads, then use glulam 115x115 in the outer wall. There are no problems with these being different, both meet the requirements to transfer the loads.
Regards
Regards
A construction tube 90x90 should work since, to my knowledge, it can handle more load than a 115x115 glulam post. The question is whether it is okay to have a glulam post at one end and a construction tube at the other; is there no issue with using different materials that potentially expand in different ways?
Andreas
Andreas
Sometimes there can be, but hardly in this case.copello2 said:
Thank you for your answers.
Does a construction tube 90x90 4 mm thickness bear the same load as a glulam column 115x115? And where can I find information about this?
Alternatively, it should work to place a 90x115 glulam column so it can be completely hidden in the inner wall. In that context, it would be interesting to know how big the difference in load capacity is between a glulam column 115x115 and 90x115.
The companies that produce glulam should be able to answer this, or are there easily accessible tables online?
Thank you for your input!
Does a construction tube 90x90 4 mm thickness bear the same load as a glulam column 115x115? And where can I find information about this?
Alternatively, it should work to place a 90x115 glulam column so it can be completely hidden in the inner wall. In that context, it would be interesting to know how big the difference in load capacity is between a glulam column 115x115 and 90x115.
The companies that produce glulam should be able to answer this, or are there easily accessible tables online?
Thank you for your input!
A column under load is subjected to buckling, meaning it wants to bend into an S shape. Compare it with taking a long piece of spaghetti and compressing it.
The susceptibility to buckling is influenced partly by material properties but also to a very large extent by the geometric shape of the column. The ratio between length and cross-sectional dimensions is critical.
Now, I don't know if 90x90 is OK, you have to ask the designer about that.
In some cases, buckling problems can be avoided by attaching the column to other building parts, for example in the middle. It is then important that these building parts are not too weak to handle lateral loads.
The susceptibility to buckling is influenced partly by material properties but also to a very large extent by the geometric shape of the column. The ratio between length and cross-sectional dimensions is critical.
Now, I don't know if 90x90 is OK, you have to ask the designer about that.
In some cases, buckling problems can be avoided by attaching the column to other building parts, for example in the middle. It is then important that these building parts are not too weak to handle lateral loads.
In these contexts, it is almost always the worst knäckfallet, articulated at both ends.
If you don't have a ceiling height higher than 2.5m, a glulam post 90x90 should be sufficient as far as I can see. Then the dimension of the beam feels very robust. An HEA160 or maybe even 140 should suffice.
I think your designer has over-engineered a bit. However, I'm a bit hesitant about placing the post on the existing sill. The strength is significantly worse across the fibers.
I think your designer has over-engineered a bit. However, I'm a bit hesitant about placing the post on the existing sill. The strength is significantly worse across the fibers.
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The matter of bringing the load down to the floor and buckling:
Whether the column wants to bend out like a C or an S - see Euler's buckling cases:
http://sv.wikipedia.org/wiki/Eulers_knäckningsfall
What it involves is whether the ends are rigidly fixed or not. When it comes to transferring loads to a concrete floor where you want a rigidly fixed bottom, it is common to use underpinning. It is suggested to use a steel column with a plate welded to the bottom. The size of the plate depends on the foundation. Here, it is important to consider the punching effect that a "sharp" column exerts on, for example, an underlying concrete slab.
The plate has four holes - one in each corner, for example, d=20. The column is placed on the foundation, the holes are marked. Then one drills into the concrete and anchors, for example, M16 threaded rod with Hilti HIT. Once the mass has cured, nuts are screwed on and the column is placed on top of the nuts. Then the nuts are screwed up so that they push the column against the slab above. The nuts are tightened until the column takes a significant load, and then nuts are also screwed on the top side.
Finally, a low wooden frame is built around the column foot using sparse paneling. Add a few decimeters in size. Concrete with a bit of flow agent is poured in and gently vibrated.
The advantage of this solution is that the column takes significant load from the start. This eliminates the risk of creaking floors and settlements on the floor above.
Whether the column wants to bend out like a C or an S - see Euler's buckling cases:
http://sv.wikipedia.org/wiki/Eulers_knäckningsfall
What it involves is whether the ends are rigidly fixed or not. When it comes to transferring loads to a concrete floor where you want a rigidly fixed bottom, it is common to use underpinning. It is suggested to use a steel column with a plate welded to the bottom. The size of the plate depends on the foundation. Here, it is important to consider the punching effect that a "sharp" column exerts on, for example, an underlying concrete slab.
The plate has four holes - one in each corner, for example, d=20. The column is placed on the foundation, the holes are marked. Then one drills into the concrete and anchors, for example, M16 threaded rod with Hilti HIT. Once the mass has cured, nuts are screwed on and the column is placed on top of the nuts. Then the nuts are screwed up so that they push the column against the slab above. The nuts are tightened until the column takes a significant load, and then nuts are also screwed on the top side.
Finally, a low wooden frame is built around the column foot using sparse paneling. Add a few decimeters in size. Concrete with a bit of flow agent is poured in and gently vibrated.
The advantage of this solution is that the column takes significant load from the start. This eliminates the risk of creaking floors and settlements on the floor above.
You say the load-bearing wall is 4 meters long, but it seems to be 4.5m in the calculations? Then it seems unnecessary to choose an HEA180 when HEA160 met the deflection requirement for the long-term load?copello2 said:
Then a small stupid question for someone who knows: Why does it say kH instead of kN in the calculations? likewise mpA instead of MPa.. for the salary demands the engineers make, one should at least get spell checking, right?