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  1. ZeroStress

    Bending Stiffness or Youngs Modulus

    Hello I'd be grateful if someone could shed some light on my problem which is keeping me awake through the nights. I am assessing a bridge deck and its construction is RC deck (280mm thick) spanning between the abutments (span is 7m). Fairly simple deck. The concrete is of 20.7N/mm2 strength...
  2. ZeroStress

    SF and BM Formulas

    Does anyone know shear force and bending moment formula for two unequal span continuous beam loaded with varying distributed load? or loaded with a point load at any location? Similar to this beam but with a VDL instead of UDL. https://imgur.com/a/RjFQGgk Thanks.
  3. ZeroStress

    Bending of Plates

    I'd be grateful if anyone can guide me in the right direction. A flat plate 2m x 2m with a thickness of 20mm (Stainless steel with fy = 220 N/mm2) is supported on two of its parallel sides and a its acting as a wall inside a chamber. The loading on this plate is a hydro static load. Am I...
  4. ZeroStress

    Grillage Analysis of a Bridge Deck

    @MotorCity This is fairly standard method of PS Beam bridges. The infilled concrete adds valuable strength to the capacity with minimal addition to the dead weight. @Agent666 You're right there are holes in web's of the beam and transverse reinforcement is passing through the webs connecting...
  5. ZeroStress

    Grillage Analysis of a Bridge Deck

    Hello I am currently assessing a bridge deck by grillage analysis. The deck consists of T4 prestressed beams closely spaced together (500 crs) and fully infilled with insitu concrete with 75mm topping. I have modelled the longitudinal grillage member representing the main prestressed beams...
  6. ZeroStress

    Strain Compatibilty Method for Reinforced Concrete

    Hello and thanks for your valuable advise. I am struggling with something that has been bothering me for a while. This is regarding finding out the ultimate bending resistance of a rienforced concrete section. I have attached the hand calcs. The concrete section in the question already has an...
  7. ZeroStress

    Shear capacity of unreinforced concrete

    If I was designing a new concrete section I'd never forget to provide a min. reinforcement but unfortunately I am assessing an existing concrete section which was built some 70+ years ago. Its a mass concrete leaf pier supporting a bridge and the record drawings indicate there is no...
  8. ZeroStress

    Shear capacity of unreinforced concrete

    It can be any type of shear, either punching or usual shear from beam loading?
  9. ZeroStress

    Shear capacity of unreinforced concrete

    Hello I am struggling to find the shear capacity of a concrete section with no shear or tensile reinforcement at all and was wondering if anyone can help me with it. BS5400-4 and BD44/15 suggest a formula for concrete capacity which is based on the tensile reinforcement ratio (100.As/bd) but...
  10. ZeroStress

    Strut and Tie Models for Concrete Pilecaps

    Hello Usually the strut in the STM is in compression but I have seen many cases where the struts come out in tension. For example when a pilecap has a large bending moment and it experiences lift off on one side, this would result in some of the struts being in tension. Eurocode gives guidance...
  11. ZeroStress

    Steel-Concrete Composite Beam FE Modelling

    Hello I am trying to model a typical steel-concrete composite beam on LUSAS (its a Finite Element Software). The actual steel beam has shear studs so the action between steel and concrete is definitely composite. Can anyone tell me if I model the steel beam and concrete both as shell...
  12. ZeroStress

    Normal or Principal Stresses

    Hi there I'd like to get some opinion on designing a concrete arch bridge. I have modelled the arch in Lusas and have a bit of confusion in what stresses should I use for its strength check. The normal stresses or principal stresses? Principal stresses are a little higher than normal stresses...
  13. ZeroStress

    Thermal Stresses and Forces

    Thanks. I think I am sort of getting the hang of the problem here. Or perhaps I am coming to terms with the fact that thermal stresses can be disastrous if not taken care of properly. I am pretty sure the stresses I calculated in my first post are true. But the deflection in the columns is...
  14. ZeroStress

    Thermal Stresses and Forces

    My mistake, I didnt clarify earlier. Lets put it this way, I am trying to find the defection of the columns. This deflection would be outwards, if the concrete slab in the middle is expanding (as in picture). So, to find the deflection of the column I would need the force generated from the...
  15. ZeroStress

    Thermal Stresses and Forces

    Hello all, I am trying to calculate the thermal stresses and forces developed into the concrete deck right at the centre line of columns, as attached in the picture. - The difference in temperature is taken as 30 deg Celsius. - Coefficient of thermal expansion of concrete is 12e-6 - Width of...
  16. ZeroStress

    Moment of Inertia of Trapezoid Beam

    Yea LT does have this command. I just created two regions, one with outside perimeter and one with inside. Subtracted them from each other and massprop gave really close results with the centroid at 0,0 coords. This probably is much more easier then downloading any specific software for...
  17. ZeroStress

    Moment of Inertia of Trapezoid Beam

    Yea I didn't have any problems in calculating the Plastic NA and then Plastic Section Modulus. But thanks SteelPE, I didn't know about this AutoCAD command before. Will give it a go, just wondering if AutoCAD Lite can perform this command too keeping in mind it doesn't have 3D capabilities.
  18. ZeroStress

    Moment of Inertia of Trapezoid Beam

    Yup. What a relief! Thanks Robert and BAretired. Your idea of taking approximate thickness of the web parallel to axis of calculation is giving very close to what the actual answer is. Thanks to all. =)
  19. ZeroStress

    Moment of Inertia of Trapezoid Beam

    Its been days since I have been struggling to get the right second moment of area for a composite beam. Attached is the section in question. Concrete slab on top of a steel trapezoid girder. I just can't get the moment of inertia for the two inclined webs of the steel girder. Tried every...

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