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Recent content by enigma2

  1. enigma2

    Wind load on tank within a masonry enclosure

    I'm looking at a 8'-0" diameter, 8'-0" tall round tank surrounded by a 14'-0" x 14'-0" x 8'-6"H masonry enclosure. It is enclosed on 4 sides and the top is open. When designing slab and foundations, do I need to consider any wind loads on the tank, or do the walls provide enough buffer that...
  2. enigma2

    Masonry Elevator Shaft Added at Concrete Building Exterior

    I have a client who wants to add an elevator shaft to the exterior of an existing 8-story building. The existing building is concrete. The floors are flat plate with no edge beams. One side of the new elevator shaft will tie into the plate at each floor. The three exterior walls will be unbraced...
  3. enigma2

    Transferring Earth Loads thru Rigid Diaphragms at Exposed Basement

    Well my initial thought with regard to considering passive pressure was that the section of wall that is only one story below grade opposite the side of the wall two stories below grade would want to move into the soil. I thought I could possibly use the passive pressure that develops as...
  4. enigma2

    Transferring Earth Loads thru Rigid Diaphragms at Exposed Basement

    I have a building roughly 300’ x 175’. It is built into a hill. There is a concrete foundation wall between the basement slab and the first floor. Between the first and second floor, the north and west walls are concrete and built into the hill. The south and east walls are mostly exposed (at...
  5. enigma2

    Side-Loaded Wood Members

    I need to support a side load off of (2) 2x12s nailed together with 3 rows of 10d nails at 12" o.c. How do I calculate the maximum point load to the outside face of the built-up member to know if it's adequate or if I need to have more nails added?
  6. enigma2

    Wide Opening in Existing CMU Wall

    Removing the wall was the original thought but with an odd high/low condition, an expansion joint between the two structures and some other issues, this was deemed the lesser of two evils.
  7. enigma2

    Wide Opening in Existing CMU Wall

    I have a new structure abutting a non-loadbearing 12" CMU wall in an existing structure. The existing wall is 50'-0 wide and 24'-0 tall and the tenants want to put an opening that is 36'-0 wide and 18'-0 tall in the wall to allow pass thru from the existing structure to the new structure. I...
  8. enigma2

    Chord Forces in Flexible Roof Diaphragm with Large Round Opening

    Sorry for the delayed response, I didn't get the e-mail notification. I think I have that fixed now. The framing is steel--WF beams with 5" HSS columns. 1-1/2" metal roof deck.
  9. enigma2

    Chord Forces in Flexible Roof Diaphragm with Large Round Opening

    I have a single story, flat roof structure with an irregular shape--close to an octagon, for the sake of the question. There is an interior courtyard space, open to the elements. The courtyard is round. As a result, the opening in the roof diaphragm is also round. The opening is about 25% of the...
  10. enigma2

    Knee-Braced Frames

    I found in AISC 360 that knee braces should be treated as moment frames since they essentially function in that regard. The Seismic Provisions consider a knee-brace system as an OMF. This would apply if we were using anything other than R=3. I agree it must fall under the "steel systems not...
  11. enigma2

    Knee-Braced Frames

    We have a low rise building with 16’-0” floor to floor heights. We had intended to utilize braced frames for the lateral force resisting system. However, in working with the owner, we could not agree on a location to obstruct tenant space. Going to moment frames is cost prohibitive. Since there...
  12. enigma2

    Foundations at Lightly Loaded Columns with Large Biaxial Moment

    I have an open structure with a fabric roof. The vertical supports are tube steel and they are to sit on a base plate anchored with epoxy anchors to a concrete slab. I have been charged with designing foundations for the 16 columns. It is a proprietary structure and the manufacturer has provided...
  13. enigma2

    WF collector to shear wall top track

    I have an interior steel stud shear wall (steel studs with gypsum sheathing) with a WF beam that runs over the top of the wall acting as a collector/drag strut to transfer the diaphragm load into the shear wall. What type of connection do I provide between the top track of the shear wall and the...
  14. enigma2

    Facade Retrofit: Alternative to Wall Tie?

    We have a project where we have been asked to come up with a solution to re-connect existing veneer to the structural back up of a 1928 structure. From what we can tell, the back up is a double wythe of clay tile and the veneer is a series of 4" thick solid concrete panels. The panels vary in...
  15. enigma2

    How Deep Is Too Deep For A Shallow Footing?

    The owner has agreed to look into the economy of deep foundations. They have a specialist on board who is working with the soils engineer to determine the best installation for the subgrade--but now it's looking like augered piles. The tunnel location is fairly well documented. I like the idea...

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