Rail-Structure Interaction using MIDAS. Sean McAuley, P.E. Scott Henning, P.E.

Transcription

1 Rail-Structure Interaction using MIDAS Sean McAuley, P.E. Scott Henning, P.E.

2 CA HSR CP miles of HSR infrastructure 18 HST Bridges 32 Roadway Overpasses 25 kv a.c. Electrification Design Speed: 250 mph/400km/hr CP 2-3

3 Track Structure Interaction Analysis Goals Ensure passenger comfort, safety, and track serviceability Investigations Frequency Vertical, Longitudinal, Transverse, Torsional Serviceability Deflections in all directions Rail Structure Interaction (Focus of this presentation) Dynamic Modeling Dynamic Impact Factor Deck Acceleration

4 Rail Structure Interaction Analysis Goals Investigate Rail Stress Investigate Relative Displacements at Expansion Joints Investigate and Limit Rail Stress and Relative Displacements to prevent rail fracture

5 Modeling Requirements Generating Geometry of the Track Ballasted Track CW Rail Centroid of Superstructure Top of Rail Tie

6 Modeling Requirements Assign Properties Rail elements as beams Only concerned with axial stress, bending stress controlled by displacements and rotations Linear springs vertically and transverse Vertical spring modeled as fully elastic for ballasted structures, uplift only checked for direct fixation fasteners Bi-linear springs longitudinally Captures fastener slip

7 Modeling Requirements

8 Modeling Requirements Assign Properties Foundation stiffness 6 DOF spring for foundation elements Approach embankment stiffness 6 DOF spring for approach For rail stress and relative displacement calculations a fixed embankment spring can be conservatively used For total displacement checks or for calculating rail-structure interaction forces (forces imposed on the bridge by a continuously welded rail) compare fixed condition and a lower bound embankment stiffness

9 Loads and Load Case Requirements Construction Stages Capture rail installation timeframe Consider/Investigate Creep and Shrinkage Generate non-linear load combinations 1. LL 2 + LF ± Temp (±40⁰ F) 2. LL 1 + LF ± 0.5 Temp + Operation Based EQ (OBE) LF includes Braking/Traction for Load Case 1 LF includes only Braking for Load Case 2

10 Live Loads Modified Cooper E-50 Loading Deflections and Rail Stress High Speed Rail Trainsets Dynamic Analysis

11 Thermal Loads ±40⁰ F Temperature Differential Temperature applied to the Bridge Simulates the effect of restraining movement of the rail due to the bridge expanding/contracting Thermal rail stress controlled by limiting thermal length

12 Analysis Types

13 Analysis Types Non-linear Static Analysis Covers non-seismic load combination Elastic Multi-Linear Link

14 Analysis Types Non-linear time-history analysis Covers seismic load combinations General Link (Force-Type-Hysteretic)

15 Analysis Types

16 Rail Structure Interaction in MIDAS Example Structure: CIP PT Box Girder span configuration Integral connection to superstructure Founded on pile group foundation

17 Rail Structure Interaction Model Features Superstructure using Beam Elements Rail using single beam to represent 2-rail track Bi-linear Springs to represent fasteners Multi-linear Elastic Links for nonlinear Static Analysis General Link for Nonlinear Time History Analysis Rail Extension to capture approach embankment Point Spring Boundary Spring

18 Rail Structure Interaction Model Features Rigid Elastic Links Elastic Links (linear and bi-linear)

19 Rail Structure Interaction Model Features Construction Stage Implementation Rail Installation Timeframe Coordinate schedule Figure 1: Completion of post-tensioning Figure 2: Rail Installation at 2 years Allows for time-dependent effects on rail to begin at proper time

20 Rail Structure Interaction Model Features Non-linear load case development Combination of static load cases into single case Cannot implement moving loads with non-linear analysis Non-Linear Time History Analysis Review Development of Analysis Model

21 Rail Structure Interaction Analysis Results Review Rail Stress Results Maximums at Expansion Joints, as expected Figure 3: Group 4 Stress Results

22 Rail Structure Interaction Analysis Results Expansion displacement within limits Figure 3: Group 4 Stress Results

23 Conclusions Lessons Learned and Troubleshooting Linear superposition (static + time history) Verify Bi-linear Link Behavior Expansion Jt

24 Conclusions Lessons Learned and Troubleshooting Creation of Critical Live Load Generates wheel loads to specified max force Write text file for static load to MCT Command shell

25 Thanks Acknowledgement California High Speed Rail Authority MIDAS Contacts Questions: Compliments: