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  1. npthao121

    shallow foundation on the week soil

    Thank for your quick response. I've got these soil information from the soil investigation report. I just take it out without review, too bad, right? I agree that it is a mistake of soil clasification. The water table is 0.6m from the ground surface. The project is a two story office...
  2. npthao121

    shallow foundation on the week soil

    Dear all, I’d like to know your advices in the following case: Soil profile: 1st layer: Sandy clay (CL-ML), 2.2m thick. SPT = 8 Wn=21.2, Wl=22.0, Wp=16.4, Ip=5.6. Void ratio e = 0.853, saturated degree S = 66% DSS test gives: phi=24o, C=0.099 kg/cm2. Sieve analysis gives: gravel (7%), sand...
  3. npthao121

    N values of densified soils

    Normally, what kind of modulus do you use for settlement calculation? from the lab test (oedometer, consolidation or triaxial) or from the field test (plate load test, SPT, CPT). And which is better (lab or field) as your opinion? somebody told me that modulus from the field test is more...
  4. npthao121

    Mortar and Grout

    The most important different between mortar & grout is shrinkage characteristic. The grout is non-shrinkage material while the mortar is shrinkage one. Moreover, the compressive strength of the grout is much higher than the mortar. The grout is normally used when: - Fill the anchor box of the...
  5. npthao121

    Soft Clay Consolidation with Lowered Water Table

    It seems to me that cracks “crumbling” pulling apart … of the exsisting building as your mention are due to consolidation settlement. With the soil profile like yours & the fill of 8-12 foot thick for residential area, the condition is matched for the consolidation settlement to be occur. 20-30...
  6. npthao121

    Soft Clay Consolidation with Lowered Water Table

    Bangkok city has been affected by water lowering until now. Some research done by AIT (Asian institute of Technology) the value of settlement due to this reason & soil consolidation is about 4in/year. But the soil parameter of Bangkok is different from Jimbo2’s. Bangkok clay is much weaker...
  7. npthao121

    SPT 'N' =0 in Clay

    Dear All, Nice thread, it is regret to join so late. VAD, BigH & Fotch 3 pointed out many good things. To ashjun, off course it is good if one post provide valuable info in short passage. But, i never be annoyed with the long one if it shows a good idea & supporting background (text book...
  8. npthao121

    Blinding Concrete - Specified Grade

    Dear all, I think, there is no specific reason for specifying two grades of the blinding concrete. We normally call it the lean concrete. its purpose is only for providing a clean surface before we pour concrete for the foundation. In Vietnam this on is specified as 100 mm thk & 10 Mpa grade for...
  9. npthao121

    Foundation on loose sand

    Chosy is right, in this case the plate load test does not work. I think you should re-investigate the subsoil by bore hole. The cost for this work is not so high in your area. If the owner refuse to do so, you better walk off from the project.
  10. npthao121

    Bearing Capacity Determinations

    In our country (Vietnam), there is a common practicing in which the report writer caculate the bearing capacity for a conventional foundation with 1x1m (width & length) at 1 m deep from the ground level. they say the bearing capacity of the conventional foundation. besides that, they also...
  11. npthao121

    Foundation on loose sand

    Are you coming from Vietnam? What is your main concern, foundation for building only or other items else? What kind of soil is below your loose sand? If it is a good layer and strong enough, why not consider the pile foundation (small concrete square pile) solution? However if you still consider...
  12. npthao121

    Design Build

    Some information I would like to add The owner of a complex project normally develop his work like this: 1. Hire a good engineering company to carry out the basic (conceptual) design & also feasibility research. This design product will be the frame of the project. 2. Hire a good engineering...
  13. npthao121

    Design Build

    Dear haynewp I am coming from an engineering company. Basically we are a design company, however during the last ten years we have concentrated on the construction works and most of the job we got up to now are based on design – build or turnkey or EPCC (engineering, procurement, construction &...
  14. npthao121

    Slab design technique

    Why don't you use hand calculation to check your Staad result. could you give more detail about your structure? what do you mean when mention "... unlike in the conventional way"?
  15. npthao121

    Correlation between horizontal and vertical permeability coefficients

    Dear CHBK, This is the table extracted from "prefabricated vertical drain: Vol 1, engineering guidelines" by Rixner J.J, Kraemer S.R & Smith A.D Soil Kh/Kv No evidence of layering (partially dried clay has completely uniform appearance)...
  16. npthao121

    beam design...???

    That's right Try to calculate by hand first, the re-analysis to check your result. it is good for you to cummulate your experience. If you gain the reletive stiffnes between two times of analysis are tolerable enough. it's the reasonable section. good luck
  17. npthao121

    Rebar Estimations

    Hi all, I have experienced with the matter regarding to YIGo question. Sometime at the site, the electric guy asks me the question like this, they just want to know how much kg per one cubic meter of concrete. Probably, they use this value to deal with their sub-contractors or estimate the...
  18. npthao121

    foundation on soft soil

    Dear all, This is a actuall case: I have a chance to visit a site which is in the same condition like yours, 11 m of weak OH soil, about 4m of surcharge by well compacted sand. Fence (by clay brick) is supported by shallow foundation placed directly on the soil. The fence high is 2.3m as...
  19. npthao121

    Overloaded pipe sleepers

    Thank everybody for your valuable ideas, I discussed with the designer and he also proposed to reinforce the beam by welding aditional channel. Fortunately, channel material is available in our site. Also i can mobilize the high quality welder from piping team. But welder may have to take the...
  20. npthao121

    Overloaded pipe sleepers

    Dbuzz, thank for you joining, I talk with the designer already and he said it is a mistake, the right section is H294x200x8x12 instead of H244x175x7x11. He did not realized when reviewing the AFC drawing. 1.11 is not a load factor; it is the demand/capacity ratio as AISC-ASD89. Load value &...
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