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User's Manual - PHI FACTOR

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User's Manual - PHI FACTOR

    PHI FACTOR AASHTO LRFD 2007 EDITION

Issue Date Subject of issue / Revision

    1 28/05/2008 First Issue

     Issue : 1 Nom Date Visa Written by : TEODOR DOBRINESCU Checked by : S.MONTENS / T.DUCLOS A.CHEIKH MHAMED Approved by : Y. GAUTHIER

    PHI FACTOR DETERMINATION

    ACCORDING TO

    AASHTO LRFD 2007 EDITION

    PHI FACTOR Page 1 / 17 AASHTO LRFD 2007 EDITION

    PHI FACTOR AASHTO LRFD 2007 EDITION

    TABLE OF CONTENTS

    ?0 : INTRODUCTION & NOTATION ............................................. 3 0.1 INTRODUCTION ....................................................................................................................................................... 4 0.2 NOTATIONS............................................................................................................................................................. 5

    ?1 : PRESTRESSED AND REINFORCED CONCRETE ................. 6 1.1 FLOWCHART ........................................................................................................................................................... 7 1.2 AASHTO LRFD 2007 EXTRACT .............................................................................................................................. 8 1.3 SPREADSHEETS LIMITS ........................................................................................................................................... 9 1.4 INTERFACE PRESENTATION ...................................................................................................................................... 9 1.4.1 INPUT range: ............................................................................................................................................... 9 1.4.2 OUTPUT range:.......................................................................................................................................... 10 1.4.3 Other element(s):......................................................................................................................................... 10

    ?2 TENSIONED CONTROLLED PARTIALLY PRESTRESSED

    CONCRETE IN FLEXURE.............................................................. 12 2.1 INTRODUCTION ..................................................................................................................................................... 13 2.2 AASHTO LRFD 2007 CODE EXTRACT ................................................................................................................... 13 2.3 SPREADSHEETS LIMITS ......................................................................................................................................... 14 2.4 INTERFACE PRESENTATION .................................................................................................................................... 14

    ?3 CONCLUSION ........................................................................... 15

    ?4 BIBLIOGRAPHY ....................................................................... 17

    PHI FACTOR Page 2 / 17 AASHTO LRFD 2007 EDITION

PHI FACTOR AASHTO LRFD 2007 EDITION

?0 : Introduction & Notation

PHI FACTOR Page 3 / 17 AASHTO LRFD 2007 EDITION

    PHI FACTOR AASHTO LRFD 2007 EDITION

    0.1 Introduction

The present user’s manual treats the spreadsheet used to determine the resistance factor (φ).

    The code used as base for the spreadsheets development was the 2007 edition of the American code

    AASHTO LRFD.

    A 1987 Transportation Research Board study concluded that the American Association of State Highway and Transportation Officials' (AASHTO) Standard Specifications for Highway Bridges contained gaps and inconsistencies and did not use the latest design philosophy and knowledge. In response, AASHTO first adopted the Load and Resistance Factor Design (LRFD) Bridge Design

    Specification in 1994 and the Guide Manual for Condition Evaluation and Load and Resistance Factor Rating (LRFR) of Highway Bridges in 2002.

    LRFD incorporates analysis and design methodologies with load and resistance factors based on the known variability of applied loads and material properties. These load and resistance factors are calibrated from actual bridge statistics to ensure a uniform level of safety.

    With LRFD, a bridge designer focuses on a design objective or limit state, which can lead to a similar probability of failure in each component. Bridges designed with the LRFD specifications should have more uniform safety levels, which should ensure superior serviceability and long-term maintainability.

    PHI FACTOR Page 4 / 17 AASHTO LRFD 2007 EDITION

    PHI FACTOR AASHTO LRFD 2007 EDITION

0.2 Notations

AASHTO EXCEL Description Symbol Notation

    ---------- type designed member’s type (i.e. prestressed, non prestressed) ---------- weight weight type of concrete (i.e. lightweight, normal weight) ---------- load loading type (see corresponding table in spreadsheet for further details) d dt distance from the extreme compression fiber to the extreme tension steel element’s centroid t

    cc distance from the extreme compression fiber to the neutral axis

    ffy specified yield strength of reinforcing steel bars y

    f fpy yield strength of prestressing steel py

    AAps total area of prestressing steel ps

    AAs area of nonprestressed tension reinforcement s

    φ phi resistance factor

    PPR PPR partial prestress ratio

    Table 1 Notations used

    PHI FACTOR Page 5 / 17 AASHTO LRFD 2007 EDITION

PHI FACTOR AASHTO LRFD 2007 EDITION

?1 : Prestressed and reinforced concrete

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    PHI FACTOR AASHTO LRFD 2007 EDITION

1.1 Flowchart

    Here below is the flowchart of the algorithm:

     Figure 1 Flowchart for calculating sections with bonded tendons

    Remark:

    For this spreadsheet, there is no VBA code implemented.

    Therefore the OUTPUT data changes automatically with

    any change in the INPUT data.

    PHI FACTOR Page 7 / 17 AASHTO LRFD 2007 EDITION

    PHI FACTOR AASHTO LRFD 2007 EDITION

1.2 AASHTO LRFD 2007 extract

     Here below is an extract of the code used as base for the sheet:

    Figure 2 Extract of the AASHTO LRFD code

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    PHI FACTOR AASHTO LRFD 2007 EDITION

1.3 Spreadsheet’s limits

    The calculated values are valid only for conventional construction (as in Article 5.5.4.2.1 [1]) for non prestressed reinforced concrete and for totally prestressed concrete.

     For compression controlled sections with spirals or ties for seismic zones 3 and 4 at the the

    extreme event limit state the user should refer to Article 5.10.11.4.1.b [1]

     Additional resistance factors are specified in Article 12.5.5 [1] for buried pipes and box structures made of concrete

    1.4 Interface presentation

     General overview: PHI Factor Determination

     Figure 3 General overview of the spreadsheet 1.4.1 INPUT range:

     Table 2 The INPUT section

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    PHI FACTOR AASHTO LRFD 2007 EDITION

    For the INPUT range there are 4 columns:

    ; Symbol indicating the name of the respective input data (for more information see

    Chapter 0.2. Notations)

    ; Value appearing in blue; it is the effective input range

    ; Unit indicating the unit of the respective input data

    ; Description brief description of the respective input data dt

    Additional geometrical input data is required for load case 1 and a schematic view of a flanged beam

    along with the identification of the required distances is present.

    ex

    cNeutral Axis

1.4.2 OUTPUT range:

     Table 3: OUTPUT section

For the OUTPUT data, the spreadsheet returns “φthe resistance factor

    1.4.3 Other element(s):

    Remark:

    The change of INPUT data will result in

    the change of OUTPUT data automatically

     Figure 4 : user instructions

    This zone resumes the steps for making calculations in the spreadsheet. It also informs the user of the

    tables that are to be used for conventional construction and for segmental construction respectively.

    PHI FACTOR Page 10 / 17 AASHTO LRFD 2007 EDITION

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