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  1. Catjacob

    Analysis of segmental bridge built by balanced cantilever method

    Hello bridge guys, I'm going to assess a 20 years old post tensioned bridge of which the concrete deck was cast in-situ with travelling gantry attached to cantilever ends. My question is, after 20 years have gone, is the creep induced by the weight of the gantry still "significant"? I mean is...
  2. Catjacob

    Transverse prestress in box girder top slab

    In designing transverse prestress in top slab of a box girder, do I have to consider the bending stiffness of the webs which !0 stops the tob slab from "free elastic shortening" and 2) picks up "some prestress load effect" reducing prestressing force in the slab betweem the webs?
  3. Catjacob

    Elastic buckling analysis

    uxbridge, i was busy with something else last week and didn't look at my problem further...But I will pick it up next week. I start to agree to what you think: the plan bracings are very effective to stabilize the steel troughs against global torsional buckling. I remember I read a book a few...
  4. Catjacob

    Elastic buckling analysis

    Thanks for your reply. I knew local buckling has not to be considered and it worries me. It is because I am not able to check whether the steel trough would fail in overall buckling until I got the first global buckling mode and its load factor… Funny thing about it is that if I assign the...
  5. Catjacob

    Elastic buckling analysis

    Hello, I am doing the design check of a multi-span steel composite box girder viaduct but struggle to get elastic buckling analysis done. To check the stability of the bare steel section under self weight of fresh concrete (i.e a steel trough supporting wet conrete), I set up a 3D model formed...
  6. Catjacob

    Grillage Modelling for Steel Single Cell Box Box Girder

    I am going to do a quick analysis for a steel box girder of 20 ft wide top flange, 14-2/3ft bottom flange and 8 ft deep. The bridge is of 11 spans (each span approx. 165 ft long) and several spans are curved in plan on a radius of 1000 ft. Over each pier, the box is strengthened with a plate...
  7. Catjacob

    Interpretation of FE Analysis

    When I did my FE course at university, I was taught how to do FE formulation (e.g. transforming a PDE into a weak form, defining primary/secondary variables) but not how to apply the results to real engineering problems. For instance, I know how to solve FE equations to find out say shear...
  8. Catjacob

    Piled Foundation on Embankment

    The slope is at about 40 degrees to horiz line. The central walls are designed to support a bridge deck. After the bridge deck or the wall has been in place, a section of the embankment is removed and a new road will be contructed
  9. Catjacob

    Piled Foundation on Embankment

    The embankment is 10m wide (at its crest) and 6m high??
  10. Catjacob

    Piled Foundation on Embankment

    Is it possoble to do secant bored piled walls on the side slopes of embankment AND a diaphragm wall in the centre of the embankment?? The embankment is 10m wide and 6m high??
  11. Catjacob

    Arch Bridge Preliminary Design

    I am going to do the preliminary design of a RC arch bridge (pinned at both ends) and would like to know the vert and horiz reactions and bending moment at the apex (Is it equal to zero??) if the arch is subject to a vertical UDL. I don't need an exact value but want to know the "order of...
  12. Catjacob

    Piles not imposing stress/load on surrounding soil

    Three weeks ago, I read a trade newspaper which reported a foundation contractor put some kind of steel sleeve over the top, say 6m, of the bore piles so that the pile would not impose any stress on the top layer of soil. Unfortunately, I can’t remember what it is now..... Dose anybody know...
  13. Catjacob

    Effective length of piers/columns and bearings

    I found from some bridge design codes assume the effective length of a column to be 0.85 (say) x physical length if the bottom end is fixed against horiz movement and rotation and the top is restrained from any horiz movement but not the rotation (i.e. a pinned joint). However, I don’t...
  14. Catjacob

    Beam and Slab Bridge Design

    When I learnt prestressed beam design at college, the section properties (e.g. I value) of the girder don’t change with time or construction stage on which equations or inequalities for the estimations of prestress force and I value are formed. However, the current problem is a beam and slab...
  15. Catjacob

    Pile Construction on Soil Slopes

    The problem I have is pile foundations for a bridge. The bridge has to span over a 12m wide moat and the slopes/banks on both sides are 8m height at 35 degrees. In addition, the site constraint includes that the construction of piles must not stabilize or loosen the soil slope. Could any...
  16. Catjacob

    Curved Bridge Deck

    For the purpose of preliminary design, is there any simple equation which can be used to work out the torsional moment of a curved bridge deck (in plan) if both ends are torsionally restrained. What I know is that the BM on the bridge is approx equal to w x (arc length)^2 /8. Another equation...
  17. Catjacob

    Steel Orthotropic Deck Design

    Can anybody give me some guidance about the design of orthotropic deck design to BS 5400:3? I have a look at 9.10.2 which deals with the design of stiffened flange and it seems that effect of buckling of the steel plate is not taken into accout...............
  18. Catjacob

    Bored Pile (1m dia) in Rocks

    Thanks you very much!!!
  19. Catjacob

    Cantilever of a box girder

    I got a compsoite box girder (steel closed box with concrete slab on top) which may cantilever from the pier at about 6m. Could any body tell me how to minimize the effects of deflection and vibration. Can I install dampers or struts of which the ends are loaded against the tip of the box and...
  20. Catjacob

    Bored Pile (1m dia) in Rocks

    Sorry for the sutipd mistake, the presumed allowable bearing pressure (kPa), is least 5000 kPa which has been factored down by a FOS of 2.5 - 3. I am going to design a group of piles to support a bridge deck which will impose a huge horiz loads on the piles. I haven't done any SI but am pretty...
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