Seismic behavior of precast

piers on high speed railway

bridges

André Monteiro

António Arêde

Nelson Vila Pouca

2016

PhD 2016 | 2

2016 CONSTRUCT PhD Workshop

1. PhD framework:

• Main work developed on the scope of the SIPAV project.

• Challenged proposed by Mota-Engil, Betões e Prefabricados:

– Full-scale application viable for high-speed railway bridges (HSRL);

– Precast solution for fast construction;

– Reinforced concrete (RC) based layout;

– Focus on the piers for seismic behavior assessment;

HSRL Precast solution RC Piers Virtually non-existent

• State-of-art of relevant areas reviewed accordingly:

• Opportunity to address the shortcoming by aiming to apply

common precast solutions for HSRL Piers as well.

PhD 2016 | 3

2016 CONSTRUCT PhD Workshop

2. HSRL Bridge Piers:

• Common Layouts for HSRL Bridge piers:

Single Column Pier

(often with flare)

• Increased stiffness relative to equivalent motorway bridge piers.

• Strict deformation limits for HSRL running safety limit state, e.g.:

– Maximum radius for lateral deflection of 1.50 x 10-3 rad;

– Maximum longitudinal displacement of 5.00 mm;

• High seismic forces are expected.

Wall Pier

Multiple Column Pier

(Bent-type column)

Tall viaducts

Long/short viaducts

PhD 2016 | 4

2016 CONSTRUCT PhD Workshop

3. Base Structure for Study:

• Poceirão – Caia HSRL proposal for long and low height viaducts:

– Double Column RC Pier (5.00m < Hpier < 20.00m);

– Short span coupling beam (αs = 1.0);

– High stiffness columns;

Seismic design guidelines:

– Plastic hinges;

– High ductility;

• Height dependent stiffness ratios lead to difficulty in evaluating

suitable locations for inelastic

deformations.

• Possibility for high shear ductility

demand in the beams.

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Cu

rva

ture

(ra

d/m

)

H (m)

Elastic 50%Col_stiff 50%Beam_stiff MomCur_BEAM

PhD 2016 | 5

2016 CONSTRUCT PhD Workshop

4. Prototype Solutions:

• Beam reinforcement layouts based on applications for coupling

beams of shear walls:

Bi-diagonal layout (Eurocode 8 / ACI318 ).

Rhombic truss (Tegos and Penelis (1988)).

Dowel Rhombic truss (adapted from Tassios et al. (1996)).

• Precast system based on a top-down assembly (2 columns +

beam), enforcing reinforcement yielding at the joint.

21

43

100% Asl

50% Asl

Moment

capacityStrain concentration Joint Opening

Monolithic Scenario Idealized Precast Scenario

VS.

Assembly Procedure

Precast Joint Reinforcement Design:

PhD 2016 | 6

2016 CONSTRUCT PhD Workshop

5. Experimental Campaign

• Test setup designed and installed in LESE accounting for:

– Constant axial loading on both columns (300 kN);

– Free rotation on column bases;

– Cyclic loading applied through shear;

Vertical Jacks Reaction Frame

Horizontal Actuator

Dywidag Ø26.5 Rods

Hinge System

Vertical Jacks

Threadbar Connection

Shear Loading Plates

Rotation Hinge

PhD 2016 | 7

2016 CONSTRUCT PhD Workshop

6. Main Observations

• Monolithic Specimens largely influenced by beam shear,

providing generally low ductility capacity.

Sliding shear

Diagonal splitting

Low ductility and energy dissipation

• Precast Specimens benefitting from the flexibility provided by the

joint, although still subjected to heavy damage.

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Fo

rce (

kN

)

Lateral Drift (%)

Collapse

Yielding_cot1.8

Fu+ = 205.48 kN

Fu- = 171.44 kN

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orce (

kN

)

Lateral Drift (%)

Collapse

Joint_bending

Beam_shear

Fu+ = 158.85 kN

Fu- = 147.99 kN

Large joint displacements

Heavy damage on larger drifts

Increased ductility

and energy dissipation

PhD 2016 | 8

2016 CONSTRUCT PhD Workshop

7. Numerical Modelling • 2D FEM based plane stress approach on Cast3m, with individual

constitutive characterization of:

– Concrete (Faria, R. and Oliver, J. (1993));

– Steel reinforcement (Menegotto, M. and Pinto, P. (1973));

– Bond-slip behavior (Eligehausen et al. (1982));

– Joint behavior (Snyman et al. (1991));

Monolithic specimen

Precast specimen

ε11 strains at first yielding:

σ22 stresses:

Monolithic specimen

Precast specimen

Rebar stresses:

Both specimens

PhD 2016 | 9

2016 CONSTRUCT PhD Workshop

8. Seismic Performance

• Experimental data used to calibrate global modelling tools for

seismic performance assessment:

– Viaduct modelling using 2D characterization in OpenSees;

– Lumped plasticity at the base of each pier calibrated accordingly, for Monolithic and

Precast specimens (Ibarra et al. (2005));

– IDA procedures (Vamvatsikos, D. and Cornell, C.A. (2002));

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CD

F (

DS

| I

M )

Instensity Measure, Sa1 (g)

Mono_yieldingPrecast_yieldingMono_ccrackingPrecast_ccrackingMono_collapsePrecast_collapse

DM #1 – Structural Damage

Comparison of different Damage Measures: DM #1 - Structural Damage;

DM #2 – Lateral Deflection;

DM #3 – Spectral Intensity;

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Drift (%)

Experimental_scaled

IMK_Pinched

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Drift (%)

Experimental_scaled

IMK_Pinched

Conclusions • A double column bent pier system was studied for

precast application;

• There is a high shear ductility demand in the beam of

the structural system, requiring unconventional

reinforcement layouts;

• Experimental evidence showed that the precast system

helps with increasing overall ductility and energy

dissipation;

• Numerical analyses confirm that the precast system is

able to globally improve the seismic performance of the

studied viaducts;

Thank you!