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Josh, thank you. The semi-flexible diaphragm modeled with plate elements seems to work just fine when the "plane stress" option is used. I did not get too deep into it but the semi-flexible VS flexible issue seems inconsequential when the plate parameters represent diaphragm materials that would...

So if I just get RISA-Floor, will life be good in terms of flexible diaphragms?

Actually I think the issue is with me, I'm still in a hand calculation mind set... Is there really any need for a "flexible diaphragm" if one is using software? Couldn't the diaphragm just be modeled with a plate using an appropriate in plane stiffness to account for nail slip etc? In which case...

Is there any way to model (efficiently) a flexible diaphragm in RISA-3D without using RISA-Floor? I have finally forsaken portal method and moment distribution spreadsheets and purchased a copy of RISA-3D to join the 21st Century, only to realize that I might need additional software to do...

hs2112, I'm in the US Northeast, and the last time I had a GPR done inside a building it was something like $1,200 for the day. There was a general contractor in the middle of it, and it was a government job so I'm not sure how the markups compare to your situation. The purpose of the GPR...

Did you say that you had the drawings? If so I would imagine that the shear studs would be called out on the drawings? If no drawings are available you can look to the existing structure for clues. If some of the member sizes are too small for the original loads when analyzed as non-composite it...

The only thing holding up the beams is the clamping pressure? I have seen a similar connection where the rods were drilled right through the column, in which case you would conceivably have to shear the rods to drop the beam. I have also seen the same thing done with wedge anchors in blind...

To connect the dots... Table 3-2 of the aforementioned DOD manual gives an allowable wall load of 565PLF for a 5" slab (wall on interior of slab). Taking the weight of an 8" CMU wall grouted 48" OC as 47PSF (ASCE-7 Table C3-1) this would give 470PLF for a 10' wall. This would agree with the...

This topic is covered in DOD UFC 3-320-06A "Concrete Floor Slabs on Grade Subjected to Heavy Loads." This is essentially a reprint of US Army Technical Manual 5-809-12. Either way it can be obtained for free at the following link: http://www.wbdg.org/ccb/DOD/UFC/ufc_3_320_06a.pdf I believe...

I believe that the equation to which Jike refers can be found in "Computation of Stresses in Bridge Slabs Due to Wheel Loads." by Westergaard, published in Public Roads Vol 11 No. 1 1930. In this paper Westergaard provides an analytical elastic analysis of concentrated loads on a slab, and gives...

The NEMA website lists ST-20 "Dry Type Transformers for General Applications" as Rescinded. Does anyone have any idea what standard will fill the void? http://www.nema.org/stds/st20.cfm

From the outter dimensions less the thickness of the foam you should be able to find the area of the steel. However you will need the thickness of the various parts of the tank to get the volume and thus the weight of the steel as EdR proposed. If the tank is UL listed (UL-142 etc) the UL...

If you are interested in the direct analysis method, you can view a quick "Boxed Lunch" seminar on the subject for free on the AISC website at this link http://www.aisc.org/Content/NavigationMenu/Learning_Opportunities/eLearning/Course_Details/A_New_Approach_to_Design_got_Stability.htm Second...

I would recomend checking "Structural Renovations of Buildings" by Newman for some ideas. I believe he may have presented a solution for a similar slab issue. I will check my copy when I get to work tomorrow.

In addition to my above post, a "fact sheet" on the WRI website says the following: "In the case of the lower layer, when the concrete slab is placed on a well-constructed base course (normally graded, compacted and porous), many who design floors consider 1.5” of clear cover below the steel...

I believe the document Teguci is referring to is ACI 360 "Design of Slabs on Ground." The only guidance given for placement of reinforcing within the slab is as follows: For Crack-Width Control - At or above mid-depth, typically 1.5" to 2" cover below the top surface of the slab. For Moment...

ASTM C494 "Standard Specification for Chemical Admixtures for Concrete" gives the following definitions: Water-Reducing Admixture - An admixture that reduces the quantity of mixing water required to produce concrete of a given consistency. Water-Reducing Admixture, High Range — An admixture...

I would just like to point out that the AASHTO LRFD Bridge Design Specifications 4th Edition has 5% adjustments built explicitly into the code. These "load modifiers" effectively allow an additional 5% capacity for structures with exceptional ductility, highly redundant load paths, or structures...

StructuralEIT - I agree that bracing in general need not be located near the compression flange to prevent beam instability. The AISC code refers to beam stability bracing as "Lateral Bracing" and "Torsional Bracing" with different stiffness and strength equations for each type. The...

I would recommend you refer to Appendix 6 of the latest AISC Specification (AISC 360-05). Appendix 6 deals with stability bracing for columns and beams. With regards to lateral bracing for beams it states "Bracing shall be attached near the compression flange...". Additionally the commentary to...