For SDC of D, looking at ACI 318-14 section 18.13.3.4: "Grade beams and beams that are part of a mat foundation subjected to flexure from columns that are part of the seismic-force-resisting system shall be in accordance with 18.6."
My situation requires large grade beams NOT spanning between...
I am designing a large but lightweight one-story steel building, similar to a PEMB. The foundation system is augercast piles due to liquefiable (seismic) soil conditions. The slab-on-grade is considered sacrificial and non-structural (so if the subgrade settles 7 inches during liquefaction, the...
Though AISC requires +1/16" oversized holes for bolts, shop drawings for weldments (angle ledgers, etc) being attached to concrete with post-installed anchors often come back with +1/8" or +3/16" oversized holes proposed, presumedly so they'll have more tolerance for installation. Are +1/16"...
I'm designing a cantilevered (steel HSS) column freestanding canopy. The architect now wants the steel columns surrounded by a wrap of brick veneer, with air gap. We're in seismic SDC=D here. First thought would be to provide veneer anchors to the sides of the HSS column. However, it would be a...
I am working on a mixed-use project that is pretty typical for the pacific northwest...3 or 4 stories of wood-framed apartments platform framed over two stories of post-tensioned concrete flat plates (for parking & retail). However, the owner and contractor think it might save them some money to...
Small diameter steel pipe piles (2 to 6 inch nominal) are fairly common in our region. I have always heard these referred to as "micropiles". However, just noticed 2012 IBC section 1810.3.5.3.2 limits minimum pipe diamter to 8", followed by an exception "There is no minimum diameter for steel...
Let's say we have a shearwall endpost holdown which utilizes SDS screws, but it's installed misaligned by one stud's width, so a short piece of 2x6 shim is needed to fill the gap. Do you think it would be acceptable to simply lengthen the SDS screws by 1.5" and assume that the shim is now acting...
When a shearwall endpost holdown which utilizes SDS screws is misaligned by one stud's width, so a short piece of 2x6 shim is needed, do you think it would be acceptable to simply lengthen the SDS screws by 1.5" and assume that the shim is now acting as an integral part of the endpost? Or do I...
I certainly understand the ASCE 7-05 Section 12.11 requirements for wall anchorage and subdiaphragms when it's a concrete or masonry wall tied into my floor. But what about light-framed wood wall structures...it seems like there is no exception to 12.11.2.2.3, so when I have exterior studwalls...
For retrofit of an existing URM building with wood joist floors, my understanding from ASCE/SEI 31-03 is that the joists must form continuous cross-ties from one wall anchorage to the opposite side wall anchorage (in the absence of subdiaphragms). Pretty straight forward. But what about the...
I have a fixed pier in a high seismic zone, for which the geotech has specified 16" square prestressed piles. For the spiral reinforcing, I need 2" cover (marine environment) so I am left with a core diameter (Dc) of 12". Works fine with equation 21-2 (ps=0.12f'c/fyt), which calculates to #3...
For tilt-up wall panels (especially 5.5" ones), how would you typically provide hooked dowels to the slab pour strip (or to a concrete mezzanine floor if needs be), since the hook development length is too long? It seems like a commonly overlooked error - even the TCA engineering manual shows...
I've got a situation that doesn't seem to fit traditional AISC theory too well...essentially a horizontal "ladder" shape made out of MC18 channels as the primary stringers (ie. the legs of the ladder) spaced about 36" apart, with C6 channel cross members (ie. "rungs" of the ladder) welded to...
OK, ASCE 7-05 is giving me a headache again. I need to determine seismic loads on a steel box truss (single angle chords at 4 corners, single angle side verticals and diagonals, single angle diagonal "wind" bracing between top chords & sim between bottom chords). This truss is used in an...
For a "sutro" (or proportional) weir, how do you calculate the force on the weir "blades"? This is an outlet for a small lake, into a channel. Is it simply the hydrostatic force, assuming the water is flowing pretty slowly on the high side, or are there significant "nozzle" type or other...
Section 1607.7.3 of the 2003 IBC requires a 6000# horizontal load (due to vehicle impact) applied on a 1.0 square foot area. I have a parking garage situation with CMU infill wall along part of the edge, which must be designed for this load. My question is, how wide of a "design strip" would...
Per IBC 2003 Sec. 1620.4.5, SRSS method is used to check separation of adjacent structures, to avoid seismic pounding. I have a new building being constructed next to an existing URM building, and no plans are available of the existing... does anyone have advice on how to rationalize a...
I have a cantilevered PSL 7x20 beam, supported at two locations by PSL 7x7 columns. The problem is that my first support (not at cantilever) has lateral bracing but the support at the beginning of the cantilever has no bottom chord bracing, and cannot due to architectural constraints. Also...
I have a weird concrete problem that I have never seen before; any advice or thoughts would be appreciated. It is a prestressed, large (2'-6"deep, 6'-0"wide, 20' long) concrete beam, simple span (so PS strands towards bottom), longitudinal mild reinforcing towards top, #5 full...
For design of reinforced masonry shearwalls, UBC97 Sec. 2108.2.5.6 references "Rw" = 1.5. What is this? A remnant from the 94 UBC? It is not listed as a variable, as far as I have seen. How should one apply it to boundary member design? Regards,
