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  • Users: johndeng
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  1. johndeng

    Punching shear on slab

    Just the questions in my mind which could be simple to your talents, but I want to know it clearly myself. Thanks For example, the punching load on top of 8" slab, 1. if the slab horizontal reinforcement is 2" from top, what's the d value. 2. if the slab horizontal reinforcement is 6" from top...
  2. johndeng

    Wind corner zone

    Hi maybe this is simple for you guys, but I want to confirm it's correct as I marked. There are some complicate building shapes, so I just thinking about this maybe helpful. Thanks
  3. johndeng

    Glass railing wind load at balcony

    Glass railing wind load at balcony is supposed to be the same as the parapet wind load design (both faces have load, positive from face of wall plus negative from roof/wall, say 100psf c&c). But the railing has 6" gap at bottom, is the wind load condition still the same as parapet? That's the...
  4. johndeng

    Why the Bridge beam support looks different from the building beam at support

    Hi I only deal with buildings. When I pass by the bridges, I can see all the beams are sitting high above the abutments. It looks like some details to lift it up at the support bearing. What's the considerations? For building beams, it only sits on a thin bearing plate. Thanks
  5. johndeng

    two way slab middle strip reinforcement

    I am checking a two way slab with 20 bays each way, each bay are 25'x25' with concrete beams 4 sides. Right now it has beams in column strip so it only used less than half of it's capacity. however the middle strip it only has one top bar #5@ 20", which is only less than half of the required...
  6. johndeng

    Unbraced length input

    Forgive me, another silly question. What do you put for beam unbraced length, a very simple example, a 20' roof beam with metal deck on top. What do you put for(Lb pos, Lb neg, L33, L22, and LTorsion)? Lb pos, Lb neg, is the unbraced length for top and bottom flange bending L33, L22, is for...
  7. johndeng

    two way VS one way concrete slab reinforcement

    Hi it might sound silly, correct any of my points if I am wrong. I think two way slab is using about 75% of the loading of one way concrete slab reinforcement calculation. So for both directions, total reinforcement should be at least 1.5 times of the one way slab reinforcement, am I right? If...
  8. johndeng

    seismic lateral load distribution for 3 hangers

    3 vertical hangers support a 1000 lbs member, the middle hanger takes 500 lbs vertical dead load, side hangers take 250 lbs each. Total lateral seismic load is 100 lbs, what's the lateral load at middle hanger, 50 lbs or 33.3 lbs? Thanks
  9. johndeng

    gatepost, flagpost, or bollard footing

    The design depth of the sonotube footing is about 10 feet. The load is the truck impact load. Right now I am thinking the post should be embed into the sonotube, not on top since the anchorage is tough. how far should the post be embedded? does the sonotube require reinforcement? bollard would...
  10. johndeng

    column effective length factor K

    Sorry if this is too beginner question. For a steel framed building, all connections are pinned, what's the k value for columns, 1.0 or 1.2? column length is from connection of girder to top of base plate, or to top of slab on grade?
  11. johndeng

    steel framed building on piles need lateral resisting system

    We have a steel framed building on piles which has no lateral resisting system. we will add cross brace, but it will transfer the load to piles. we are thinking of add grade beams between the two pile caps, or install additional battered piles. If we use grade beam, the piles will take moments...
  12. johndeng

    COLUMN K VALUE

    The one story parking garage is attached to a building. Parking slab is precast plank, and supported by big steel girders and masonry wall both ends. The other direction are only small tie beams and no masonry wall. Wall direction (e-w) can be treated braced, the other direction (n-s) may be not...
  13. johndeng

    pile capacity

    Just wondering if we call the piles/ pile caps are 20 tons piles, we can put total service load 40kips on the pile, or can only be 20kips (factor of 2)? thanks
  14. johndeng

    can we camber and shore girder at the same time

    Just wondering for composite girders, I called cambers based on composite section, say 1" camber. But during concrete pour, the dead load on steel girder would be 2", should I call shore during concrete pour? Thanks
  15. johndeng

    composite slab on cantilever beam

    Just wondering composite slab on cantilever beam, the slab will crack in tension, so cantilevered portion of beam can not be treated as composite, can only be checked with non-composite. For the non-cantilevered portion of beam, any problem to be treated as composite?
  16. johndeng

    the difference for the surcharge load of 1 feet area or 100 feet area behind the retaining wall

    There is 1 feet of distributed surcharge load 300psf, or there is 100 feet of distributed surcharge load 300psf right behind the retaining wall, what's the difference of the soil pressure due to the surcharge load? say wall retaining height 6'. I can only figure they are the same with...
  17. johndeng

    add panels on roof, does it add wind load to roof structure members?

    MWFRS wind load for flat/monoslope roof is only uplift load, no downward load. so we don't add wind load for joist/girder design. But when we add tilted panels on half of the roof, panels will take uplift and downward wind load, most time downward wind load is over 20psf and uplift is only...
  18. johndeng

    Splice two gratings

    We need grating to cross span 8', but the contractor only makes 3'x4' grating, so we'll need to put(2)w10x12 splice below. w10x12 splice beams are at each side. w10x12 will have to take all the middle span moment, welding between the grating and w10 will make them composite beyond middle splice...
  19. johndeng

    antique flexicore planks repair

    We have a recent project which we found the antique flexicore planks made in the 60’s need repair. The old style plank is not like prestressed plank nowadays. They are made of blocks that are held together with reinforcing steel that appear grouted in place. Reinforcing steels located in the...
  20. johndeng

    For wind load, masonry shear wall, moment frame, and cross bracing which is the best option?

    to control story drift, my experience is shear wall is the best, then cross brace, the least is moment frame. Any opnion?

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