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  1. fracture_point

    AREMA Rail Design - Spanning between posts without supporting beam

    I'm working on a project where we are trying to determine how far a 136lb AREMA rail can span between posts. The architect wants to maximize the spacing between posts just using a column cap, but we are trying to assess how far these things can span without have a support W-beam beneath.(see...
  2. fracture_point

    ETABS API - GetGridSys_2

    I'm writing some code to draw gridlines through the API using Python, but for some reason the ETABS model does doesn't reflect the data. There is no error showing in my console so it seems like the code passes. xGrids = [0,5,15] yGrids = [0,5,15] xGridNames = ["1","2","3"] yGridNames =...
  3. fracture_point

    SetPresentUnits and SetPresentUnits_2 in ETABS API

    I have tried using both the SetPresentUnits and SetPresentUnits_2 methods in the ETABS API when running my script to draw my framing. It works and places the elements with the correct geometry, however the default viewing units in the model returns to imperial, rather than staying as it has been...
  4. fracture_point

    Add Area by Coord Method - ETABS API

    I'm trying to write some code in Python that draws a slab in ETABS. However, API documentation is scarce for Python for this method. An example is given for VB: 'add area object by coordinates ReDim x(5) ReDim y(5) ReDim z(5) x(0) = 50: y(0) = 0 x(1) = 100: y(1) = 0 x(2) =...
  5. fracture_point

    Error when getting Python to attach to ETABS

    Hi, I'm using the following code: import sys import comtypes.client try: myETABSObject = comtypes.client.GetActiveObject("CSI.ETABS.API.ETABSObject") except (OSError, comtypes.COMError): print("No running instance of the program found or failed to attach.") sys.exit(-1) SapModel =...
  6. fracture_point

    Why isn't continuity of moment around a rigid joint fulfilled under a buckled shape?

    I'm studying from Stability of Structures by Yoo and Lee, and the example is deriving the buckling capacity of a simple frame. In the freebody diagram, there isn't moment continuity around the rigid corner. That is, there's tension on the right side of the column member at the corner, but...
  7. fracture_point

    Question regarding Ultimate Limit State Design

    I was doing some additional background reading on ULS design, and found the following quote on wikipedia: I can't find a reference for the approximation of 15%. We perform sectional analysis of members based on the plastic condition, and these loads are based on partial factors of safety to...
  8. fracture_point

    Seismic design of squat walls - response modification factor

    I'm looking at the seismic design of a series of squat walls (h/l < 2.0) and determining the forces to design them with. Initially, the structure was intended to be designed with special reinforced walls using a response modification = 5 to reduce seismic forces by. Following this through to...
  9. fracture_point

    Interpretation of ASCE 12.9.1 - Modal Response Parameters

    I want to clarify my understanding of this, as I am performing a response spectrum analysis. Using gravity = 9806 and R = 5, Cd = 5, I = 1 in ETABS scaling factor, which of the following options is correct. 1) For member forces: 9806/(5/1) = 1961 Deformations/drifts: 9806 x (5/1) = 49030 OR...
  10. fracture_point

    Seismic Design of Cantilever Stringer Staircase

    Hi all, Hoping you can offer me some guidance/point me in the right direction with resources to my current problem. The architect wants a staircase that is cantilevered from the main structure suspended into an atrium space (see attached paint diagram). It is likely these moment connections...
  11. fracture_point

    Two-way Slab Design - Column Strip vs Band width

    Hi, I have some confusion regarding the strip method that is used and general convention that is used within my company. The company uses finite element analysis to determine forces with column strips defined as L/4 of the minimum bay dimension to average the moment over and design the steel...
  12. fracture_point

    Non-Sway Frame Column

    In the design of a non-sway column, is it necessary to perform a p-delta analysis if you are using the moment magnification method if the column is slender (as per ACI)? Or is the moment magnification a method used in lieu of having to do p-delta? If the latter is true, if we have a stocky...
  13. fracture_point

    Modal Response Spectrum Analysis Forces for Foundation Design

    Response spectrum forces are often outputted from design software (e.g. ETABS) as MAX and MIN envelope values, as in the worst case loading but these load cases do not occur at the same time (it may show two columns going into compression or tension instead of tension & compression couple). How...
  14. fracture_point

    Euler Buckling vs Moment Magnification - RC Columns

    Can someone clarify the difference to these two methods? In school using Eurocode, I remember checking columns against Pcr (Euler buckling) and if the axial load exceeded this, the column would buckle and fail. However, in A23.3 it seems to use a moment magnification method, which calculates...
  15. fracture_point

    Cracked vs Uncracked RC Sections - Modal Analysis/Response Spectrum

    Couple of questions regarding model analysis and cracked/uncracked section properties: 1) Do we use cracked section properties for all of the modal analysis, i.e. to calculate periods, base shear, drifts, forces etc and would also give a worse p-delta effect.. or 2) Do we use uncracked...
  16. fracture_point

    Design of C-shaped and rectangular core walls

    Hi, Does anyone have any good references for the design of C-shape concrete shear walls? I'm looking for specific examples where the analysis and design treats the wall as a complete section, as opposed to splitting it into 3 individual planar walls. I have searched through my design books but...
  17. fracture_point

    Overturning moment on core walls supported by raft

    I have four core walls surrounding a staircase that is subject to tension/compression in opposite walls under seismic loading. The walls will be supported on a raft foundation. What is the best way to model the tension piles to determine the distribution of axial force into each pile? I do not...
  18. fracture_point

    Deflections under seismic loading

    The NBCC (Canadian building code) allows us to reduce the base shear by multiplying by a factor of IE/RDRO. The code then specifies that for deflections, the values should be multiplied by RDRO/IE. My question is, should we be multiplying the reduced base shear values by this factor, to bring...
  19. fracture_point

    Design Forces from Response Spectrum Analysis

    When the modes are combined with various methods (CQC, SRSS etc.) the sign of the displacements and forces are lost within most software, so often when analysing forces due to a response spectrum load case the laws of static are often not obeyed. I have a shear wall being supported on a...
  20. fracture_point

    Seismic Analysis (Static ELF) - Which period to use?

    Hi all, Firstly, let me state that I am going to be undertaking both a static analysis and a dynamic analysis (response spectrum) as I want to compare forces and scale them if necessary. For the ELF in the x-direction, the first mode has a period T = 2.4s, and excited about 16% of the seismic...

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