Giải thích hệ số PBN - Kennedy and Sennah

Task 2 – Range of structural forms, materialsand range of application  There is no reason at this point to limit range of application we can include range outside of conventional practi

Kennedy and Sennah

better accuracy)

European Practice

Summary

Task 2 – Range of structural forms, materials

and range of application

 There is no reason at this point to limit range of

application (we can include range outside of

conventional practice and geometries)

 “All” parameters will be included in the

database

 A large amount of data is available from

several sources (see Task 6 tables)

 Additional data can be added

Task 3 Analytical method

Task 3 Analytical method

 Numerical methods

 Finite difference

 Finite element method (plate or shell elements)

 Grillage

 Finite Strip Method

 Harmonic analysis (Sanders and Elleby)

Theorem Requirements

forces are in equilibrium

must be ductile

Independent of themodeling assumptions!

No instability or fracture

The lower bound theorem is one of the most important

theorems/concepts in

structural engineering.

The lower bound theorem is

one of the most important

Task 4 Process Detail and Chaining

Effort Do it? Sample

1 12-50 -> BRASS -> Computation -> 12-50 Small yes

2 12-50 -> BRASS -> Input File -> FEA -> 12-50 Large yes

3 12-50 -> BRASS -> Input File -> FSM -> 12-50 Medium yes

Process NCHRP 12-50

CSA NCHRP 12-62

TN Tech, Set 1

12-26

Task 4 Process Matrix

Notes NCHRP 12-50 TN Tech Set 1 NCHRP 12-26 CSA Sanders LRFR AASHTO Std S/D equation, program into an automated approach process 1 process 4 process 7 process 10 process 13 process 16

AASHTO LRFD LRFD Eqs, program into an automated approach process 1 process 4 process 7 process 10 process 13 process 16

AASHTO LRFD Lever Rule Program into an automated approach process 1 process 4 process 7 process 10 process 13 process 16

AASHTO LRFD Rigid Method Program into an automated approach process 1 process 4 process 7 process 10 process 13 process 16

Sanders Program into an automated approach process 1 process 4 process 7 process 10 process 13 process 16

Canadian Specification (CSA) Program into an automated approach process 1 process 4 process 7 process 10 process 13 process 16

Henry (Modified) Program into an automated approach process 1 process 4 process 7 process 10 process 13 process 16

Rigorous FEA FEA engine and/or a commercial FEA engine process 2 process 5 process 8 process 11 process 14 process 17

Rigorous FSM Available FSM program process 3 process 6 process 9 process 12 process 15 process 18

Task 6 – Parametric Study

 321 Total Data Sets

 AASHTO Type A

Task 6 – Parametric Study

 176 Total Data Sets

 AASHTO Type K

Task 6 – Parametric Study

 74 Total Data Sets

 AASHTO Types E and J

Task 6 – Parametric Study

Task 6 – Parametric Study

 Spread Concrete Boxes

Task 6 – Parametric Study

 307 Total Data Sets

 AASHTO Types D, F, and G

Task 6 Wood Bridges

Additional Load Distribution Issues

Parameters Skew Barriers Diaphragms Location

Location (e.g Fatigue) Maybe Yes Maybe Yes

Additional Parameters

Perform separate parametric studies to focus

Three primary questions for the

panel

lanes

Number of Lanes Loaded

•Issue for our study – not total design load for girder systems

•Integer number

or decimal value

•Should not be overly sensitive to

Live Load Position – Interior Girder

6-4-6-6 (critical)

6-4-6-4-6 (critical)

6-6-6-6-6 (critical)

Live Load Position (exterior girder)

2-6-4-6-6

2-6-4-6-4-6

2-6-6-6-6-6

Multiple Presence – separate from

live load distribution

 Task 6 distribution factors will be computed for

one-, two-, three-, etc-lanes loaded This could be

combined, if necessary, later

 Research simplified methods will not include m.

 Rearch simplified methods will permit one-, two-,

three-, etc-lanes loaded to be computed and

independently applied

 The specification can clearly indicate (apriori)

how the number of controlling lanes, i.e., it can be

0.851.01.2

MultiplePresenceFactor

z.Z3

y.Y2

x.X1

FactorRequired byMethod

Number of

lanes loaded