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Recent content by Perception

  1. Perception

    Influence Line Resources

    Hello everyone, I am studying for the vertical breadth portion of the S.E. exam, and I’m feeling a bit overwhelmed with influence lines. I’m studying using SERM and understand the concepts, but don’t see any resources for influence lines that are available in the various code books we’ll get...
  2. Perception

    AutoCAD Copyright

    Not sure where to ask this question. I’m looking to publish an engineering book, and want to know about the permissions/copyright needed to use AutoCAD drawings I drafted in the book. Do you need permission to use AutoCAD drawings in a book? Do the drawings have to be produced on a specific...
  3. Perception

    LRFD Wood Design

    I agree LRFD is fundamentally different with the statistical modeling, but I feel like they could have made that change and still kept everything in terms of stress. I wonder what the motivation was at the time to move to everything in terms of strength.
  4. Perception

    LRFD Wood Design

    Interesting discussions. I'm going to stick to teaching ASD with a small intro to LRRD. My wood design examples are by hand so I don't have the issue of trying to utilize the results with something else that is LRFD. This discussion reminds me of when I worked at a firm doing steel connection...
  5. Perception

    LRFD Wood Design

    I am a faculty member that teaches wood design as part of an advanced structural design course. In the past I've primarily taught ASD with a short introduction to LRFD wood design. My understanding has been LRFD wood design is not commonly used in practice given the extra factors and with the...
  6. Perception

    Example calculation for Fig. 28.5-1 in ASCE 7-16

    Hello everyone, I am new to the simplified envelope method for low-rise buildings with simple diaphragms (ASCE 7-16, Section 28.4). I am trying to understand how the simplified design wind pressures at 30 ft that are shown in Fig. 28.5-1 are computed. I tried calculating some of the values...
  7. Perception

    Precast wall panel mix design criteria

    Hello everyone, I am working on a project to evaluate the use of a lightweight 1/4 - 1/2 in aggregate for use in non-structural lightweight precast wall panels. I am having trouble finding specifications that a mix like this would need to meet, such as 1-day and 28-day compressive strength...
  8. Perception

    S.E. Exam Question Clarification

    Thanks, StrtPono. That answer makes perfect sense, as shear and axial deformations are not known for being ductile. This semester, I am teaching a structural dynamics class. Since I covered the basics of ASCE 7-16 for buildings, I decided to also cover how to compute seismic forces using...
  9. Perception

    S.E. Exam Question Clarification

    Hello everyone, I wanted to get some clarification on problem 903 (bridge question) of the NCEES SE Practice Exam. I'm not a bridge person, so perhaps I'm missing something. In the problem, the response modification factor is applied to the overturning moment in multiple column bents...
  10. Perception

    Transfer Length in Prestress Concrete

    I am aware that the development length has two distinct stages in prestress concrete. The formula for just the transfer length part is 1/3*fse*(strand diameter) According to PCI, the definition of fse is as follows (pg. 2-7, 7th edition): fse = effective stress in prestressing steel (after...
  11. Perception

    Transfer Length in Prestress Concrete

    Hello everyone, PCI has a formula to calculate transfer length as follows (section 5.2.3): Transfer Length = Effective Prestress/3 * strand diameter Does anyone know where this formula came from? Conceptually, I don't understand why a stress computed considering total losses (service level)...
  12. Perception

    Baisc Prestress Loss Question

    Hello, I feel kinda silly for asking this, but I have a basic conceptual question about losses in prestressed concrete. Shrinkage, creep, elastic shortening, etc. will cause a concrete member to reduce in volume. This reduction in volume leads to the development of forces in the concrete and...
  13. Perception

    Wood Design and Ultimate Strength

    Hello everyone, I'm new to LRFD Wood Design, and I can't find a good source that discusses the stress-strain curve of wood as it relates to ultimate strength. For steel one of the main additions in the introduction of LRFD was the use of ultimate strengths that looked at where the material...
  14. Perception

    Moment Capacity of Composite Floor Girder

    That's interesting hokie66. Is there a AISC provision that addresses this or a study to back this up?
  15. Perception

    Moment Capacity of Composite Floor Girder

    Thank you Seth. I'm curious what RAM does when the beam is sloped at greater than 10 degrees. I guess you could detail how many ribs would actually fall onto the girder, and thus find the space available for installing shear studs. Just to clarify if you don't consider a girder to be braced by...
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