Energy Absorbing Beam-Column Connections

BEB801 – Project 1

Keagan Leamy n8329559

Presentation Overview

• Problem Overview

• Research Background• Concrete Connection Types

• Energy Dissipation Devices

• Proposed System• Model

• Loading

• Results

• Conclusion

Problem Overview

Beam-Column connections are vulnerable locations in a structure, especially under seismic loading.

𝐹 𝑡 = 𝑀 𝑢 + 𝐶 𝑢 + 𝐾 𝑢

Dynamic Energy = Energy to Vibrate Structure + Energy absorbed + Energy to deform structure

Aim to increase energy absorbed, reducing energy to vibrate and deform structure

Cyclic Loading

Boundary Conditions used for Seismic Loading, Cantilever

Column (Xue & Zhang, 2014)

Concrete Connection Types

• Monolithic Cast-In-Place

• Precast

• Ductile Connection

• Moment Connection

• Composite Beams

Monolithic Cast-In-Place

Example Reinforced Concrete Connection Geometry and

Steel Layout (Li & Pan, 2004)

Monolithic Cast-In-Place

Typical Failure mode and Flexural Cracks of a Monolithic Connection

(Parastesh, Hajirasouliha, & Ramezani, 2014)

Flexural Cracks began to form in both column and beam at half theoretical ultimate load

Precast - Ductile

Example Precast Ductile Connection Geometry and Steel

Layout (Khaloo & Paratesh, 2003)

Precast - Ductile

Typical Failure mode and Flexural Cracks of a Precast

Ductile Connection (Khaloo & Paratesh, 2003)

Connection prevented

crack propagation

from beam to column

Precast - Moment

Example Precast Moment Connection Geometry and Steel

Layout (Parastesh, Hajirasouliha, & Ramezani, 2014)

Precast - Moment

Typical Failure mode and Flexural Cracks of a Precast Moment

Connection (Parastesh, Hajirasouliha, & Ramezani, 2014)

Cracks occurred at connection zone, preventing flexural cracks to form in beam

Composite Beams

Example Composite Beam Column Geometry and Steel Layout

(Xue & Zhang, 2014)

Composite Beams

Typical Failure mode

and Flexural Cracks of

a Composite Beam

Section (Xue & Zhang,

2014)

Severe Cracking due to

neutral axis being closer to

slab.

Performance very similar to

cast-in-place systems

Energy Dissipation Devices

• Friction Damper

• Shear Links

• Viscoelastic Damper

Energy Dissipation Devices

Idealised Hysteresis Loops of Energy Dissipation Devices (Constantinou, Soong, & Dargush, 1998)

Friction Damper

Prototype Friction Damper (Morgen & Yahya, 2004)

Designed to aid with gap

opening behaviour of post

tensioned pre cast beams.

Increased energy dissipation of

specimen significantly.

Friction Damper

Simplified Numerical Model for Friction Damper (Valente,

2013)

Energy Dissipated by

structure decreased as

energy dissipation was

concentrated in device.

This reduced the plastic

demand of the structure.

Shear-Links

Schematic Diagram of an Aluminium Shear Link Included

into a Chevron-type OCBF (Rai & Wallace, 1998)

Viscoelastic Damper

Picture of Viscoelastic-Wall Dampers (Liu, Wang, & Ren,

2015)

Proposed System

Proposed System

Proposed System - Control

Parameter Value

Stiffness: 𝒌 =𝟏𝟐𝑬𝑰

𝑳𝟑 = 0.527 × 106𝑁/𝑚𝑚

Mass (kg) 6932.2kg

Circular Frequency of Vibration: 𝝎 =

𝒌

𝒎(rad/sec)

= 8.72𝑟𝑎𝑑/𝑠𝑒𝑐

Period of Vibration: 𝑻 =𝟐𝝅

𝝎(sec) 0.72sec

Frequency: 𝒇 =𝟏

𝑻1.4 Hz

Proposed System - Control

-1.5

-1

-0.5

0

0.5

1

1.5

0 1 2 3 4 5 6 7

Forc

e (

kN

)

Time (s)

Force vs Time Graph

Proposed System - Control

Proposed System - Device

Variable Parameter Value

Breadth b (mm) 450

Thickness d (mm) 40

Length L (mm) 270

Mass (kg) 38.151

Young’s Modulus E (Mpa) 200 000

Second Moment of

Area 𝐼 =𝑏𝑑3

12(𝑚𝑚4)

2.4 × 106

Axial Stiffness=𝐴𝐸

𝐿(𝑁/𝑚𝑚)

13.333 × 106

Lateral Stiffness=12𝐸𝐼

𝐿3(𝑁/𝑚𝑚)

0.293 × 106

Proposed System - Device

Proposed System - Results

Proposed System - Results

-15

-10

-5

0

5

10

15

0 1 2 3 4 5 6 7

Dis

pla

cem

ent

(mm

)

Time (sec)

Comparrison in Displacement vs Time with and without Device

Control Device

Proposed System - Results

-30

-20

-10

0

10

20

30

-0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4

Forc

e (

kN

)

Displacement (mm)

Hysterises Loop For Device

Conclusion