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  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 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...
  4. 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...
  5. 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...
  6. 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...
  7. 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)...
  8. 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...
  9. 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...
  10. Perception

    Moment Capacity of Composite Floor Girder

    Hello, I have a few questions on computing the moment capacity of a composite steel deck + concrete slab beam system as follows: 1) If a girder only has simply supported beams framing into it on one side, are the beams considered as lateral bracing points assuming web shear plate connections...
  11. Perception

    Incorrect formula for composite design in AISC?

    Hello everyone, I have a question about the formula to compute the moment capacity of a composite beam when the PNA is in the flange of the steel beam. I am perplexed by the formula given by AISC to compute moment capacity. First the stress distribution that AISC bases their formula off of is...
  12. Perception

    Concrete slab on Composite Steel Deck Design

    Hello everyone, I am getting into composite floor system design, and I have a quick question about utilizing the Vulcraft steel decking catalog. 1. Are the concrete slabs in the composite tables capable of carrying the superimposed live loads allowed for the deck? I saw that Vulcraft listed...
  13. Perception

    Concrete Interaction Diagrams

    Hello everyone, I have a question about the range of values interaction diagrams are produced for. From what I can tell most sources only produce interaction diagrams from gamma = 0.6 to gamma = 0.9, where, gamma*h = center - center distance between longitudinal rebar. Does any one know the...
  14. Perception

    Bearing on Experimental Beam Design

    Hello everyone, I am designing a reinforced concrete beam to be broken utilizing our Civil Engineering lab. The beam will be put into 3 point bending until it fails. The beam will be supported by resting on two W24 x 192 sections. I am looking to get a flexural failure out of the test, so I...
  15. Perception

    Snow Load Questions

    Hello everyone, I have two general questions about snow load calculations in ASCE 7-10. 1. In section 7.6.1 it is mentioned that: "Roofs with an eave to ridge distance, W, of 20 ft or less, having simply supported prismatic members spanning from ridge to eave shall be designed to resist an...
  16. Perception

    Question about example from Blodgett

    Hello everyone, I am looking at an example from Blodgett where the resultant shear force on a weld group is found. The weld group is loaded with both an in plane and out of plane load at an eccentricity. The example is shown in the attachment. What I don't understand about the example is why...
  17. Perception

    Derivation of bolt group moment of inertia

    Hello everyone, I have a formula that I can not seem to derive. The moment of inertia for a bolt group is given about the x axis (at C.G. of bolt group) as: Ix = 1/12*[nb^2*(n^2-1)] where n = rows of bolts, b = spacing between bolts I tried assuming the bolt group had a unit width with a...
  18. Perception

    Nomenclature for Joist

    Hello everyone, I am looking at a set of plans that are using custom designed joists for a roof. I don't have as much experience with the nomenclature for custom joists. On the plans there are joists called: Joist Designation = 96G14N12.8k On the roof, 2 simply supported beams frame into...
  19. Perception

    Plastic Neutral Axis in Composite Beam

    Hello everyone, I have a question about locating the plastic neutral axis in a composite beam. In a steel design book it is stated that the plastic neutral axis will be located in the slab if: a < ts where a is the depth of the compression block, and ts is the thickness of the slab. Wouldn't...
  20. Perception

    Reinforced Concrete Columns and the Plastic Centroid

    Hello everyone, I don't understand why it is necessary to sum moments about the plastic centroid when analyzing columns with axial loads + moments. In theory shouldn't the sum of the moments about any point on the cross section produce the same results? In beam analysis this was the case...

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