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  1. Olivaw

    Modal Mass Participation

    I am designing a 10-story building with 2 basement levels. Im using ETABS. I don't know if there is something wrong but I have low mass participation ratios on the firts couple of modes. See tables below. Mode 2 has 24% mass participation, but mode 20 has 18% and mode 21 has 12%. Mode 1 has...
  2. Olivaw

    Preliminary Design for Shear Wall Buildings

    Thank you GErald123, I made an excel spreadsheet to calculate the shear distribution. But I haven't been able to reproduce exactly the same results as ETABS.
  3. Olivaw

    Preliminary Design for Shear Wall Buildings

    I am designing a 10-story building with 2 basement levels. When running the model in ETABS, several walls are not functioning properly. They have shear stresses exceeding the maximum allowed by the code. I haven't been able to obtain reliable results from the model. Some walls experience...
  4. Olivaw

    Basement wall design - Load combinations

    My local code (Chile) is based on ASCE 7. It defines the additional soil pressure due to earthquake as an uniform load applied to the basement wall: σs = 0,3 CR γ h A0 / g. I asked another engineer and he told me I should apply both pressures in the same load combination. I looked up another...
  5. Olivaw

    Basement wall design - Load combinations

    I know that when a basement wall is restrained by a floor slab, you have to use the K0 coefficient since the wall is subjected to at rest lateral earth pressure. I also know how to calculate the seismic lateral earth pressure as defined by my local code. But I don't know how if I have to...
  6. Olivaw

    Elastomeric isolator connection

    I'm designing the connections of a seismic elastomeric isolator, but I'm having problems with yielding of the base plate. I'm getting about 1 3/4'' thick. What I've seen so far on other connection details of isolators, is about 3/4'' thick. I'm using AISC Design Guide 01. For base plate...
  7. Olivaw

    Steel chevron brace into reinforced concrete frame

    Im working on a 6 story plus 2 basements shear wall building on a high risk seimic area. Due to architectural concerns we can't add more walls on the first floor to resist the seismic load. So we came up with the idea to add a steel chevron brace on some concrete frames on the perimeter of the...
  8. Olivaw

    What measures can you take against buoyancy on a building?

    A few days ago we solved this problem. We had made a SAFE model of a raft foundation, but the concrete material had the wrong density on the program, so it wasn't adding all the weight from the foundation slab. Once we fixed that, we had enough weight to control overturning. It wasn't my most...
  9. Olivaw

    What measures can you take against buoyancy on a building?

    There is this proyect on my office: a 6 story building with 2 basements and a high water table (about 20 ft of water pressure). We have enough dead loads to resist uplift from hydrostatic forces, but ASCE 7 guidelines says that we need to check both earthquake and soil pressure loads (E and H...
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