Tension-only lattice members are "plates" or "rods" described in the spec. If they never see compression, they are not subject to buckling checks, i.e., not subject to slenderness checks. Also consider that if lateral load is reversed (wind and movement of superstructure can act in almost any...
Gerber beams are non-redundant and a poor choice for bridge building. I wouldn't expect a lot of rebar in the so-called internal hinges which are designed for zero moment transfer by employing e.g., corbels or by terminating flexural reinforcement.
There is an additional term to the shear flow for beams with stepped changes in flange inclination. Should be found in e.g., eurocode design guides. VQ/I applies to prismatic members.
PS. Weight does not seem to have been a concern if the beams really are 10 inches (250 mm) deep with roughly 75...
If you are using beam elements for e.g., a truss (CHS and SHS seem to imply this), this aspect of structural modelling does not matter in any practical applications. Connect the beams at their centroids. Your figure is also probably not to scale - make it to scale and read e.g., eurocode 3...
Steel doesn't typically crack or lose large amounts of stiffness from formation of plastic hinges at joints. Concrete cracks and loses large amounts of stiffness (particularly beams, less so shear walls and columns). Therefore, applying more or less aribitrary stiffness reductions to steel...
I wrote that welding vertical and horizontal continuous plates to the section will increase torsional stiffness and lateral inertia. If you have "cantilever bending" as you describe, you are dealing with both warping torsion and weak-axis-bending - both of which are greatly reduced with the...
Discrete web stiffeners (with or without the proposed bearing plate) will not increase torsional rigidity. If you want to prevent lateral movement, your best option is to weld web plates to one or both sides of the beam, and to connect these web plates to the beam web with horizontal plates at...
First off, there will not be compression in the weld. Web to flange welds transmit shear. Point loads causing in-plane normal stresses are the exception, but I assume that is not the main load on this structure.
Is the red line a top flange? If so, size the weld with beam theory to resist the...
I am not convinced that the rigidity was evaluated. The crossbeams connect to the verticals with only two bolts above the top flanges (rest are in the web area, providing minor bending resistance and stiffness), the end-plate is thin, verticals seem to lack web stiffeners at the crossbeam flange...
For steel, the von Mises criterion predicts yielding with remarkable accuracy and therefore also onset of plasticity, necking and failure - principal stresses do not.
No, and it's stated in the name: yield criterion. Hardening changes the stress-strain relation after yielding, but this stress is not the material's yield stress, nor its ultimate stress.
Furthermore, some codes applying von Mises equivalent stress and ultimate tensile strength in capacity...
To make a box section (torsion constant, warping constant and torsional shear flow of a box), you need to close the section. Choosing a type of full pen weld that ensures a complete joint penetration full-strength joint is another matter.
MTSOE: in the transverse direction (out of plane bending of the wide flange), there is negligible fixity. The wide flange has a small minor axis bending stiffness and the tube is not connected to the flanges, implying that only the web (a plate with very small bending stiffness) resists the...
Do note that the nomogram by Dalal assumes a rigid joint between the struts of different area and second moment of area, which is not applicable to the strut you posted (welding a tube to a wide flange web will not create a rotationally stiff connection).
Vertical shear is transferred by the webs. In theory, the bending and shear capacity is not affected by this weld, but in practice, there is no point in creating a box section without achieving a closed section's torsional characteristics, so I'd recommend a full penetration weld at the reds...
Nomograms can be useful, but I wouldnt use one for a buckling check without first validating it, and if you've done that, you may just as well make a FE model.
There is no "simple check" for this, and although the buckling capacity is theoretically a function of the whole member length and its properties, a short wide flange at the ends would not change the global behavior by much, unless the buckling length changes radically (L increases by 15%: -->...
If you have access to more than one crane, you could just make it a 4 or 6-point lift, increasing the LTB capacity considerably.
If you assume a composite section, make sure to cut the slab near the girder flange in a controlled manner. A quick and dirty demolition might damage the shear studs...
Are you removing the concrete slab before lifting? I assume you will, since the weight of the slab is probably greater than the weight of the adjacent girder, and in that case you cannot assume it to contribute to section stiffness. How was the bridge originally built? If there were no props...
Sizing a weld for the force resultant, assuming it to be under pure shear, is conservative (see any textbook on steel design for the derivation), so just equate the HSS yield force (area*yield stress) to the strength of the weld in shear (weld strength * perimeter * throat thickness) and solve...
