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  • Users: xkybb
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  1. xkybb

    Questions on NEC ECC Option B Regarding Withdrawl of Instruction under a CE

    Thanks for asking. PMI means Project Manager Instruction CE means Compensation Event Both are the terms from the NEC Engineering Construction Contract (ECC).
  2. xkybb

    Questions on NEC ECC Option B Regarding Withdrawl of Instruction under a CE

    Hello! I am currently working as a Project Manager's Delegate for a construction contract, and would like to seek for your advice on the following:- Background: A PMI was issued to instruct the Contractor to adopt alternative construction method for the works under the Contract. The...
  3. xkybb

    Minimum Strength of Concrete

    But why does higher strength concrete has better durability? What are the correlation between strength and durability?
  4. xkybb

    Rebound Hammer Test

    thanks for both of your answer. But is the Contractor right about point 1 & 3? 1. Top surface of the grout is the weakest because it was the first batch of grout poured contacting with and displacing the soil debris inside the pile base; 3. Coring on the pile is difficult which may damage the...
  5. xkybb

    NEC3 ECC Option A

    Do anyone know the intention of NEC3 ECC to split the duties of the Employer into two independent roles, i.e the Project Manager and the Supervisor? Why there is any needs to allow two parties, one responsible for testing and defect, one responsible for others contract administration issues?
  6. xkybb

    Minimum Strength of Concrete

    Hello everyone! I noticed that a minimum concrete strength is usually specified in designed code for concrete subjected to extreme environmental condition (eg. marine concrete). Could anyone explain the purpose of setting such a limit? For example, In BS6349, minimum cube strength of marine...
  7. xkybb

    Rebound Hammer Test

    Hello everyone! I involved in a marine foundation project where rock socketed steel H-piles were constructed (see attached). The piles are roughly 20m deep sitting on the bedrock, each pile consisted of a permanent steel casing of 610mm dia. inside placed with a steel h-section. Grout of...
  8. xkybb

    Testing of Grout

    Further information The pile is a bored pile with a 610mm permanent steel casing, inserted with H piles and the grout is only used to fill the void between the pile shaft and the steel H pile.
  9. xkybb

    Testing of Grout

    Thanks for the replies. Non-shrink grout was used for my project. The grout was mixed with water, cement and admixture (Cebex 100). The grout has never failed in an expansion test, while I would want to know the purpose of having such a limit on the free expansion % in the Contract. Also...
  10. xkybb

    Testing of Grout

    Also In case of construction of socketed steel h-piles surround by grout, what should we do if: 1. The bleeding test fail? 2. The free expansion test fail?
  11. xkybb

    Testing of Grout

    Hello! In my country, grout for pile is tested to ensure compliance with the following criteria: 1. 28 day Compressive Strength 2. Flow Cone Efflux Time > 15s 3. Free Expansion < 10% in total 4. Bleeding < 2% in first 3 hours; < 4% in total and 24 hour reaborption I understood that the control...
  12. xkybb

    Colebrook White v.s. Manning Equation for Pipe Flow

    So no one would use Colebrook White Equation for gravity pipe design?
  13. xkybb

    Colebrook White v.s. Manning Equation for Pipe Flow

    Does anyone know please? : [
  14. xkybb

    Colebrook White v.s. Manning Equation for Pipe Flow

    Hello! I know that both Colebrook White Equation and Manning Equation are commonly used for the design of gravity pipe flow. However, it is more common in my country for people to use: 1. Colebrook White Eqaution for gravity pipe flow 2. Manning Equation for open channel flow Does anyone...
  15. xkybb

    Design of Simple RC Substructure

    Reply to CBSE, If I design and detail it as "free", will the be any weak zone of cracking between the wall-column connection as the wall bend inward when subjected to soil pressure? Or it wont happen as long as I check that the wall satisfy the SLS deflection requirement?
  16. xkybb

    Design of Simple RC Substructure

    Reply to SteynW, Thx for your answer. I am wondering if I design the connection as "free", while I detail and build it as fixed into the columns, whether it would arouse unexpected and not designed forces/moment transferred to the column from the wall, and endanger the structural safety of the...
  17. xkybb

    Stiffness Matrix Method

    Reply to angrypom, Really thx to your explanation and I found it very useful. Based on my understanding, is that means the inclusion of material non-linearly is only used to achieve a more economical design, and when the designer want to further reduce the resultant forces/moment on the...
  18. xkybb

    Stiffness Matrix Method

    Hello! According to my understanding, Stiffness Matrix Method is often applied for structural analysis (both computer and manual) in obtaining the forces/moments in structural elements. However, it seems that the Stiffness Matrix Method and the Beam Curvature equation only works when the...
  19. xkybb

    Design of Simple RC Substructure

    Hello! I am designing a simple rectangular RC structure (8x8m) with 2 stories (A superstructure and substructure of 4m height respectively). 1.The structure consists of 4 columns (400x400mm) in 4 corners extending to the raft foundation. 2. The ground floor slab (200mm) and top slab (200mm)...
  20. xkybb

    Raft Foundation on Rock

    Anyone can help me ?

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