RC slabs to beams transfer load

Because of node limitation in SAP2000 Student version (100 nodes max) only small/ moderate numbers of meshing shell elements in my SAP models, it’s about 80 nodes. For calculation beams bending moment hope it would be satisfied :(    ??

tributareas01.gif 

Cases :

  1. Modelling structures with frame element to represent beam and column. Loads applied to beam in -z direction, distributed as trapezoidal and triangular.
  2. Modelling structures with frame element to represent beam and column, shell element for slabs to study force distribution on beam members. Here’s eccentricity being ignore to simplify.
  3. Modelling structures with frame element to represent beam and column, shell element for slabs. Here’s eccentricity being considered to study force distribution on beam members. How these take effect on beams internal force. Adjacent node shell to beams are connected with rigid link to transfer slab forces.
  4. tributareas1.png 

    Download Files  to see more details you can read/download here: load-path-on-rc-building-structures.pdf

6 thoughts on “RC slabs to beams transfer load

  1. Pak/Om/ syukur alhamdulillah saya nemuin weblog berisikan tentang struktur teknik sipil, setelah beberapa waktu mencari sumber sebagai refensi untuk penyusunan skripsi tahun ini. kalo boleh, saya minta saran/pendapat mengenai judul skripsi saya…saat ini saya ambil struktur beton…
    terimakasih sebelumnya…

  2. trimakasih, syukur juga. mas Fauzi lagi nyusun skripsi … ga usah bingung cari judul :) sebenarnya banyak lho masalah sipil/struktural yg bisa buat topik. keliatannya sih, kita sudah semua dapet dari kuliah tapi setelah baca2 artikel dari banyak sumber yg mempunyai konsep agak lain atau baru. akan menjadi pertanyaan balik buat diri sendiri. oo… ya saya dulu skripsi perencanaan bangunan bertingkat struktur beton, ada beberapa masalah lanjut yg menurut saya perlu dibahas diantaranya :
    – pembesaran momen sekunder kolom (moment magnifier method), perbandingannya dgn analisa orde ke-2 (P-delta) baik akibat defleksi lantai maupun kolom member itu sendiri (global and local). untuk struktur baja sudah ada.
    – distribusi beban gempa tiap portal akibat eksentrisitas bangunan tinjauan statis atau dinamis jika memungkinkan (kalo ngga yg dinamis graybox aja pake software SAP). untuk statis sudah ada.
    – perbandingan analisa dan design plat program bantu SAP/SAFE dan cara konvensional desertai teory dsar pendukungnya. sudah ada juga namun pembandingnya kurang variasi type slabs.

    kalo mas fauzi bahas itu saya akuin salut dgn kemauannya.. and saya juga IA ada waktu bantu dgn obrolan tekniknya plus ref. links. ok, GL

  3. maksudnya graybox itu apa mas?teman-teman saya banyak juga yang belum dapat judul lho mas?ada saran?sebenarnya aku agak giman gitu klo teman-teman buat skripsi cuman biar cepet lulus bukan untuk mencari pengetahuan, minimal untuk dirinya sendiri lah.

  4. maksud sya dari kata grey box itu begini, pada permasalahan lain kalo kita meninjau tekuk kolom dari model elemnt shell, algoritma dan prosedur dari software FE propietary itu ga didokumentasikan dan lagipula itu perhitungan yg sulit. Cara untuk mengujinya ya dengan rumus sederhana, diketahui nilai Panjang, Elastisitas dan Inersia lalu dihitung kalkulator tangan berapa beban kritisnya.. gitu

    kalo graybox dalam permasalahan distribusi beban gempa dinamis begini, untuk portal 2D masih memungkinkan untuk diuji dengan perhitungan tangan, sedangkan jika analisa dimanis 3D itu sesuatu yg sulit. maka cara yang sederhana ya dibadingkan dengan 3D statik.dalam arti analisa dimanis 3D tidak berbeda jauh/menyimpang jika analisa dinamis 2D nya sudah diuji.

  5. To begin with, congratulations for your informative blog and all the effort you have made for every single post.

    I am a student civil engineer in National Technical University of Athens, Greece and for my diploma thesis, I have chosen to analyse and design a reinforced concrete building.

    What is troubling me the most, is the beam-shell interaction.

    I have tried your test-cases for a simple frame as well as the cases that you are trying here (https://syont.wordpress.com/2010/06/29/balok-portal-pd-beban-layan-tinjauan-pesegi-dan-t/).

    Unfortunately, I get the same “saw tooth” bending moment diagram for gravity loads. In the spectrum analysis, the result gets even more messed up.

    How have you come over this issue?

    The best approach I was thinking is to ignore eccentricity of the shell elements and to use them only to simulate the non-diaphragmatic behavior of the building. Underestimating the bending moment in the middle of the beam spans.

    But what if you have different beam sections at the same level (floor)? (ex. B30/60 and B30/40) Connecting centroid with centroid would be wrong. But connecting top-offsets would mess up with the shell elements.

    Thanks in advance,
    Nikos Papandreou

    1. hi,

      when using rigid links to connect beam and shell element it will produce bending moment diagram with saw shapes to balancing axial force in beam element, the magnitude are depending on beam/shell mesh division. more element meshed will smoothing results.

      and further calculation are needed to combined with axial were it’ll occurs due to beam offset.

      in case of different result along lines in same floor level, this modeling are accurate enough rather than using simple assumption, but time consuming in further calculation as describes above. centroid with centroid of each different beam can be connected with rigid links.

      regards,

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