Post TensionEd Concrete Slabs

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Tutorial Post-tensioned concrete slab EN1992-1-1 Tutorial of post-tensioned concrete slab EN1992-1-1 Luk Dlouh 2 All information in this document is subject to modification without prior notice. No part or this manual may be reproduced, stored in a database or retrieval system or published, in any form or in any way, electronically, mechanically, by print, photo print, microfilm or any other means without prior written permission from the publisher. Scia is not responsible for any direct or indirect damage because of imperfections in the documentation and/or the software. (1) Copyright 2011 Scia Group nv. All rights reserved. Table of contents 3 Table of contents 1 Description of the tutorial ....................................................................................................... 12 Input .......................................................................................................................................... 32.1 Material characteristics ................................................................................................ 32.2 Supports ........................................................................................................................ 32.3 Loadcases ..................................................................................................................... 42.4 Loads ............................................................................................................................. 52.5 Combinations ................................................................................................................ 52.5.1 Combination in case of real tendon .......................................................................... 52.5.2 Combination in case of equivalent load .................................................................... 62.6 Classes .......................................................................................................................... 73 Design of the prestressing ...................................................................................................... 83.1 Design of prestress force ............................................................................................ 93.1.1 Concrete cover .......................................................................................................... 93.1.2 Maximal stress in strand ......................................................................................... 103.1.3 Determination of prestress force load balancing method .................................... 104 Prestressing of 2D members in Scia Engineer ................................................................... 144.1 Three possibilities of prestressing input ................................................................. 144.1.1 Definition of the equivalent load .............................................................................. 144.1.2 Real tendon on the 1D rib ....................................................................................... 194.1.3 Real tendon on the 2D member directly ................................................................. 214.2 Real tendon input ....................................................................................................... 215 Results .................................................................................................................................... 285.1 Mesh settings, size and refinements ........................................................................ 285.1.1 Recommended values of the Mesh size ................................................................. 285.1.2 Setting for using Hanging nodes ............................................................................. 285.2 Averaging strips ......................................................................................................... 286 Evaluation of internal forces ................................................................................................. 306.1 Elementary design magnitudes - results ................................................................. 316.2 Elementary design magnitudes concrete ............................................................. 366.3 Shear effect during design of reinforcement ........................................................... 417 Design of nonprestressed reinforcement ........................................................................... 447.1 Concrete 2D data ........................................................................................................ 447.2 User reinforcement ..................................................................................................... 457.3 Design of necessary area of non-prestressed reinforcement ............................... 487.3.1 Design ULS ............................................................................................................. 487.3.2 Design ULS+SLS .................................................................................................... 517.3.3 Summary from Design ULS+SLS of longitudinal reinforcement ............................. 547.4 Definition of column head .......................................................................................... 567.5 Definition of additional required reinforcement ...................................................... 617.5.1 Definition of additional longitudinal reinforcement .................................................. 618 Check punching ..................................................................................................................... 648.1 Punching data ............................................................................................................. 648.2 Punching check .......................................................................................................... 659 Check of prestressed concrete ............................................................................................ 699.1 Check of prestressing reinforcement ....................................................................... 699.1.1 Stress prior an after anchoring (chapters 5.10.2.1 and 5.10.3(3) from [1]) ............ 709.1.2 Stress limitation due to cracks or deformation from characteristic combination (7.2(5) from [1]) ............................................................................................................................ 719.2 Check of allowable concrete stresses ...................................................................... 729.2.1 Concrete stress after anchoring .............................................................................. 73 Tutorial of post-tensioned concrete slab EN1992-1-1 Luk Dlouh 4 9.2.2 Concrete stress under characteristic combination longitudinal cracks (7.2(2)) ... 749.2.3 Concrete stress under quasi permanent combination nonlinear creep (7.2(3)) .. 759.3 Check capacity ............................................................................................................ 769.4 Check crack width ...................................................................................................... 7610 Check deflection code dependent calculation (CDD) ................................................ 7810.1 Concrete combinations .............................................................................................. 7810.2 Code dependent calculation ...................................................................................... 7910.3 Stiffness presentation ................................................................................................ 8110.4 Deformation check ..................................................................................................... 8410.4.1 Total deflection ...................................................................................................... 8410.4.2 Additional deflection .............................................................................................. 8611 Summary and conclusions .............................................................................................. 8712 Bibliography ...................................................................................................................... 88 Tutorial of post-tensioned concrete slab EN1992-1-1 Luk Dlouh 1 1 Description of the tutorial The idea of this tutorial is to provide the user with information how to define prestressing in such a type of structure and perform the design of required reinforcement and verify the structure according to EN1992-1-1 [1]. Two main types of modelling such structure are described in this tutorial: - Model with real defined prestressing tendon - Model using equivalent load method Each model is explained later in the text (from chapter 4). Some of the detailed outputs are demonstrated mainly for the typical slab S138. This example does not deal with the user definition of a structure. Input and definition of the typical entities as beams, slabs, load cases, combinations etc. are explained in the other manuals or tutorial. This manual is especially designed for experienced user and focuses on the definition, calculation, design and check of prestressed 2D structures. A prestressed 1D structure is not described in this manual. The calculation of the column is also explained in a different manual. The design example proposed in this tutorial is related to a small five floor parking house. The building is designed in category F. The floor structure is directly subject to the load by transport. The columns are rectangular with dimensions BxH =0.55x0.55m. The slab thickness is 290mm. The dimensions of the static system are the following. - nx