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  1. BryanStein

    Thermal Movements in Large Format Structures

    There are lots of good guidelines to use for predicting volume change movements in large structures. Once a structure reaches a certain size, expansion joints are required becuase the stresses to restrain the thermal (creep, shrinkage) movements become excessive. This is a major consideration...
  2. BryanStein

    Slab Buckling

    Great post by Structuresareus. Just one oversight needs to be mentioned. Any downward loading on the end walls should be tranfered into a footing and not into the slab unless you design the slab for this end load and resulting moment. If the downward load from the end walls is transfered into...
  3. BryanStein

    Concrete International Magazine Article

    Agreed that it has been very interesting reading. It is difficult, however, (as is often is when attorneys are involved) to tell which side is actually telling the truth ... or reporting the full story. It appears to me that the judges decision was dictated not by the facts of the case, but...
  4. BryanStein

    re_bar couplers use in R.C.C

    Just for completeness, let me add that the "slackness" issue with many threaded couplers (especially with load reversals) has not been addressed by any governing body. It is an area that needs some research to determine the "real world" affect on structures. The intuitive...
  5. BryanStein

    Working Loads Vs Limit State Loads

    I haven't read much that I agree with yet. Concrete is not designed with Limit State Design (LSD). It is designed with Ultimate Strength Design (USD). There is a huge difference. Steel LRFD is not a limit state design. LSD in steel is more like full plastic design. LSD in concrete is a...
  6. BryanStein

    P-delta effects per 97 UBC 1630.1.3

    You are correct. The amplification factor should be applied to the story shears. A response spectrum analysis would use a modal superposition to determine the forces. I believe the IBC will actually tell you that a response spectrum analysis should not be mixed with P-Delta amplification factors.
  7. BryanStein

    "Rubber" Pad @ Truss Connection?

    Several posters have nailed the purpose of the pad ... to avoid an end moment connection to the column. I've investigated several failures where the end connection was designed as simply connected but erected with hard connections on top and bottom chords. I've made it a practice to stop the...
  8. BryanStein

    torque tensioning

    You're about to make a HUGE mistake. TORQUE CANNOT be converted to TENSION. AISC allows erectors to callibrate torque to tension on an individual site basis and forces consistency with thread lubrication, etc. As soon as a change is made, the correlations are invalid. I suggest you use the...
  9. BryanStein

    How to select and scale ground motion records

    You need to talk to a geologist .... Preferably one who specializes in seismic records. I've done this a few times myself, but always with factors provided by and derived by a geologist. This applies to the site records, not the scaling factors. There are several good sources for the proper...
  10. BryanStein

    re_bar couplers use in R.C.C

    RiBeneke, A Linton Threaded coupler is the only threaded coupler that does not have any "slack" in the threads because the threads are tappered ... similar to iron pipe threads. Any non-tappered threads will have some slack as a result of the tolerances required to thread a female...
  11. BryanStein

    Who would tell me the creep and shrinkage functions in ACI 209R-92?

    Look them up in ACI 209 or any GOOD text book. Good engineers realize these type calculations are only "order of magnitude" type calculations and adjust or tweek the equations to reflect the reality of their situation.
  12. BryanStein

    Ties at anchor bolts

    NO. But, make sure the loads don't pull the anchor bolt out. ACI 318-2002 (and the IBC 2000) has an appendix that give a method to check this.
  13. BryanStein

    Fly Ash in Theoretical Concrete Mix Design

    Type C fly ash is reactive and most common on in western us. It is more reactive than type F because type C has more free calcium ---- more alkalinity. Calcium hydroxide (lime) is a by product of cement hydration. Fly ash in the presence of free lime and moisture and alkalinity will hydrate...
  14. BryanStein

    ACI 318M-02 Anchorage rules

    Hooked bars have a clearly defined developement length per ACI-318. Additionally, hooked bars for shear purposed are considered "anchored" (ACI-318's word, not mine) when they are below a #5 and are bent around the flexural reinforcing. Does this mean they are fully developed? It is...
  15. BryanStein

    Interstitial condensation - dew point

    I've got a chart, but don't know where I got it. Do a google search. it'll come up.
  16. BryanStein

    hi all how can you calculate the

    AHHH, finite element modeling of concrete. I like to see it because it eventually means more work for me. Few people properly model the cracking effects of concrete they run a FEM of concrete. I've often found good old horse sense works best when analyzing concrete. Be careful with FEM of...
  17. BryanStein

    Anchorage to Concrete according to ACI318/02

    There isn't one. Your limited by the manufacturers literature and tensile capacity of the concrete. I always require random testing of bars (drilled and grouted) when I use them and only use them in direct tension in an emergency. Be careful with the allowable loads/stresses vs ultimate or...
  18. BryanStein

    Allowable amount of Unhydrated Cement Particles???

    Ron and Blues are on the money. There will be some quantity of unhydrated cement in all concrete. Studies have shown that a w/c ratio of 0.28 is required for 100% hydration in sealed laboratory specimens. In the field, good hydration is achieved above 0.40. Any w/c less than that would led...
  19. BryanStein

    Garage Floor Overlay

    GOod luck and I don't envy your situation. Sorry no suggestions.
  20. BryanStein

    Reinforcing Bars - Stabbing into wet concrete

    Concretedoc is right. Its done all the time and there is nothing wrong with it, IF, IF, IF, there is proper developement length embedded on both sides of the joint. Many times, slabs or foundations are not thick enough to get adequate embeddment. Thus, the bars must be bent 90 degrees to get...

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