2020 Midas Civil Webinar
Automation of Refined
Grillage Model for MultiGirder Bridges
Yun Lin, PhD, PE
yun.lin@greshamsmith.com
Overview of Grillage
Model
How does Bridge
Automation Improve
Engineering workflow
How to Create Automation
Program Compatible with
Midas Civil
The barrier of refined analysis is diminishing!
In lieu of more refined analysis,........
In absence of a more refined analysis, …….
For……, a more refined analysis is required.
Unless a more refined analysis is made, an approximate……
…………….
Benefits of
Refined Analysis
• More accurate representation of structures
• More accurate results
𝐷𝐿 + 𝐿𝐿
𝐷𝑒𝑠𝑖𝑔𝑛 𝑅𝑎𝑡𝑖𝑜 =
𝐶
Approximate
and Refined
Analysis
𝐶 − 𝐷𝐿
𝑅𝑎𝑡𝑖𝑛𝑔 𝐹𝑎𝑐𝑡𝑜𝑟 =
𝐿𝐿
Detailed
Grillage
Model
General
Process of
FEA
Modeling
Automation
How does
Automation
Program
Work?
Read User Input
(Span length, overhang,
beam spacing, beam
section, Strands …)
Translate inputs into
FEA languages
(Nodes, Elements,
Stiffnesses, Loads,
Boundary Conditions, …)
Output Midas Civil
Model Script in MCT
format
(Arrange data to be
compatible with your
FEM software)
Import MCT to Finish Modeling
PSC Bridge (simples span) Example
Span 1
Span 2&3
• Node / Element:
*NODE
*ELEMENT
• Section / Material:
MCT Commands
(PSC Girder Bridges
‘Grillage Model’)
*SECTION
*TDM-ELAST
*TDM-LINK
*MATERIAL
*TDM-TYPE
• Load / Load Case
*STLDCASE
*SELFWEIGHT
*AREA-PRESSURE
*USE-STLD
*BEAMLOAD
*CONLOAD
• Boundary Condition
*RIGIDLINK
*CONSTRAINT
*ELASTICLINK
• Tendon / Prestress Force:
*TDN-PROPERTY
*TDN-PROFILE
*TDN-PRESTRESS
*AETD_TENDON_LOSSES
• Moving Live Load:
MCT Commands
(PSC Girder Bridges
‘Grillage Model’)
- Continued
*MVLDCODE
*LINELANE
*VEHICLE
*MVLDCASE
• Grouping:
*GROUP
*BNDR-GROUP
*LOAD-GROUP
*TENDON-GROUP
• Construction Stage:
*STAGE
*STAGE-CTRL
*CPOSECT4CS
• PSC Design:
*DGN-MATL
*LOADCOMB
*PSC-DGN-PARAM
Create Nodal Table (*NODE)
// Highlighted areas represent direct or indirect user-input
Title = “*NODE”
m=1
for i = 0 : No_of_Span - 1
for j = 0 : No_of_Girder - 1
for k = 0 : No_of_Node_per_Girder - 1
x = ...... //Define x coordinate based on user input
y = ...... //Define Y coordinate based on user input
z = ...... //Define z coordinate based on user input
M_node[m-1] = concat[num2str(m), ”,” num2str(x), “,”
num2str(y), “,” num2str(z)]
m=m+1
return M_node
return M_node
return M_node
M_node = stack(Title, M_node)
Define Tendons Profiles
Definition of One Tendon Profile
Define Tendons Profiles (Line 1)
NAME = S1B1L1, Tendon_6/10, 1to12, 0, 0, SPLINE, 3D
Tendon Profile Definitions (Line 1)
NAME = S1B1L1, Tendon_6/10, 1to12, 0, 0, SPLINE, 3D
Tendon Profile Definitions (Line 1)
Customized to your needs
Full control of modeling
Advantages
over Struct.
Wizards
Quick strand profile definition/modification
Load cases can differentiated instead of just CS loads.
Easier to modify
Eliminate the process of Mat/Sec definitions
Analysis/ Design settings can also be automated
Benefits?
EFFICIENCY
REPEATABILITY
EASIER TO CHECK
Email: yun.lin@greshamsmith.com