While assigning plastic hinges, I have an option of using ASCE 41-17 (Seismic Evaluation and Retrofit of Existing buildings". I will be using ETABS 2017 for performing Pushover Analysis. Until now, I have decided to go with "Displacement Co-efficient method". I'll be performing "Non-Linear Static Pushover Analysis" for my model.
I am interested in performing "Performance Based Design" for a 20 story building. Preferable bar size for stirrups (Normally #3, or #4 bars are used). Minimum reinforcing bar size used for flexural reinforcement of this beamĮ. Structural frame system used (OMRF, IMRF, SMRF, etc.)ĭ. Earthquake zone or seismic design category of the area in which the structure is located.Ĭ. It would be better & simplify the detailing a lot, if the beam is subdivided into 4-equal parts, before analysis.Ĭ. Image showing required shear reinforcement values, after changing the active units to 'kip-in' for all the structural parameters, similar to ETABS 9. In case your lengths in 'inches', and shear reinforcement in in 'sq.in/in.' units, you may calculate required stirrup spacing, similar to column tie spacing discussed earlier, keeping in view relevant ACI requirements.Ħ. For exact detailing of the 18 ft span referred beam, following further information is required:ī. Now referring to the beam shown in your attached image, the value shown in the middle (0.1000), indicates maximum required shear reinforcement applicable to middle portion of the beam, whereas the other two values (0.1521 & 0.1351) are the maximum required shear reinforcement, to be placed at the relevant beam portions adjacent to supports (columns) on the relevant ends. This spacing will however subject to relevant provisions of ACI 318-08 Chapter 21, depending upon the earthquake zone or design category of the area in which your structure is located.ĥ. Upto which distance, what stirrup spacing is to be provided depends upon the shear force distribution along the beam, as will be clear from shear force diagram for the controlling load combination. Calculation of required stirrup spacing is similar, to that described for the ties in case of columns in my earlier post.Ĥ. If the beam is not subdivided into smaller parts, shear reinforcement value would generally be larger at both ends, as compared to that for the middle portion of the beam.(Beam in your attached image is indicating the similar results.)ģ. For these beams, ETABS indicates shear reinforcement at 3 points along the beam _ at the start, at the middle and at the other end of beam span. In case of beams supported at both ends, shear force (& accordingly, shear reinforcement) is more near the beam ends, as compared to middle portion of the beam. Otherwise you might miss some important point.Ģ. However, in order to understand the explanation given in the following, you will need to change active system of units your model to 'kip-in' for all quantities.
In these later ETABS versions, systems of adoptable units have been improved, and new options of units have also been implemented. You are probably using ETABS 13 or later version. In the following explanation, I am referring to ETABS version 9.7.4, with active units of 'kip-in' for all quantities.
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