# Seismic Retrofit of Steel Truss Bridge Using Buckling Restrained Damper

^{*}

## Abstract

**:**

## 1. Introduction

_{c}/L

_{total}) of the BRD was taken to be 0.2 to 0.4, and the axial strain was shown to be higher than 3%. For common BRBs, the length ratio typically varies from 0.6 to 0.8, and the axial strain is 1% to 2%. Therefore, they investigated the buckling load of the BRD in two cases: (i) the yielding core was placed in the middle of the BRD, and (ii) the yielding core was placed at the one end of the BRD. The authors also compared the energy dissipated by the BRD with a reduced length of the yielding part and the energy dissipated by a conventional BRD. The study showed that higher buckling capacity is achieved when the short yielding core is placed at the one end of the BRD; therefore, the BRD with the short core has a higher energy absorption capacity of 1.3 times than that of the conventional BRD.

## 2. Analysis Model

#### 2.1. Model of the Existing Bridge

_{y}= 355 N/mm

^{2}) and SM400 (yield stress, σ

_{y}= 235 N/mm

^{2}). The mass density, Young’s modulus, and Poison’s ratio of each steel are taken to be ρ = 7.851 × 10

^{−9}t/mm

^{3}, E = 2.0 × 10

^{5}N/mm

^{2}, and ν = 0.3, respectively. Moreover, beyond the yield stress, the material stiffness is assumed to be E/100, and the elastic-plastic behavior of von Mises type with kinematic hardening rule is assumed.

^{−9}t/mm

^{3}, E = 2.1 × 10

^{4}N/mm

^{2}, and ν = 0.2, respectively. The damage in the concrete deck slab is not taken into account in this study; therefore, the simplified elastic model is employed to consider its spatial stiffness and inertia in the dynamic analysis.

#### 2.2. Safety Evaluation of the Truss Bridge Members

- when the normal stress of the member is positive (in tension):$${R}_{t}=\frac{{\sigma}_{idm}}{{\sigma}_{i,\text{}yd}}1.0$$
- when the normal stress of the member is negative (compression):$${R}_{c}=\frac{{\sigma}_{idm}}{{\sigma}_{i,\text{}rd}}1.0$$

## 3. Seismic Upgrading Model with BRDs

_{y}of the BRD yielding core is 225 N/mm

^{2}. Young’s modulus of steel and Poison’s ratio are taken to be E = 2.0 × 10

^{5}N/mm

^{2}and ν = 0.3, respectively, and the elastic-plastic behavior of von Mises type with kinematic hardening rule and the uniaxial stress-strain relationship with hardening slope 3E/100 are assumed. The yielding part of BRDs is modeled by 2-node truss-element T3D2. The non-yielding part of the BRD is considered to be absolute rigid, and 2 beam-elements and 2 truss-elements are used in modeling of two pairs of BRDs. The damping properties of each model with BRD are assumed to be the same as the damping properties defined for the model without BRD.

## 4. Parametric Evaluation of the BRD

- Length of the yielding core, L
_{c}: 10.5, 7, 3.5 and 1.75 m - Cross-sectional area of the yielding core of the BRD, A
_{c}: 5, 10, 20, 30 and 40 cm^{2} - Inclination of the BRD, α
_{d}: 0°, 5°, 10°, and 15°.

#### 4.1. Influence of the BRD Location on the Axial Stress of the Damaged Members

#### 4.2. Influence of the Length of the BRD Yielding Core on the Axial Stress of the Damaged Members

_{c}) on the axial stress of the damaged members is discussed in this section based on the model with the L-BRD. For this purpose, the ratio between the length of the yielding core and the total length of the BRD (L

_{c}/L

_{total}) is chosen approximately to be 0.85, 0.6, 0.3, and 0.15, and depending on these values, the variable lengths of L

_{c}are given by 10.5, 7.0, 3.5 and 1.75 m, respectively.

_{c}is given by 10.5, 7.0, 3.5 and 1.75 m, the axial compressive stress is reduced by 17.9–68.0%, 23.3–72.1%, 24.5–76.6%, and 52.0–78.4%, respectively, and the axial tensile stress is also reduced by 5.1–13.8%, 5.2–21.3%, 5.6–33.7%, and 6.1–41.9%, respectively. It can be observed that the axial stress reduces as the length of the yielding core decreases. The damage may be occurred due to the length change of the members, and thus, the horizontal displacements at the moveable end of the damaged members are determined from each BRD model to verify the above observation. The horizontal displacement results are shown in Table 6.

_{c}is given by 10.5 to 1.75 m, the horizontal displacement in compressive direction is reduced by −7.4–59.3% while in the tensile direction it is reduced by 74.9–91.6%. It indicates that as the core length L

_{c}reduces, the horizontal displacement at the moveable end of the damaged members is reduced. As a result, the axial stress can be significantly reduced, providing evidence that shortening the yielding part of the BRD is effective not only in reducing the horizontal displacement change at that joint but also in reducing the axial stress on the damaged members.

#### 4.3. Influence of the Cross-Sectional Area of the BRD Yielding Core on the Axial Stress of the Damaged Members

_{c}, is made that as can be seen from the results that when L

_{c}= 3.5 m and when its cross-sectional area, A

_{c}is given by 5, 10, 20, 30 and 40 cm

^{2}, the axial compressive stress is reduced by 24.5%, 44.5%, 72.2%, 74.7%, and 76.6%, respectively, and the axial tensile stress is decreased by 5.6%, 6.3%, 22.5%, 27.2%, and 33.7%, respectively as shown in Table 3. It indicates that as the cross-sectional area of the yielding core increases, the axial stress can also be significantly reduced. Figure 8c shows the plastic behavior of each BRD.

_{c}increases from 5 to 40 cm

^{2}, the horizontal displacement in compressive direction is reduced by 7.1% to 69.4%, while it is in tensile direction, which is 71.6% to 95.8%. The results prove that the horizontal displacement of the moveable end of the damaged members is reduced as the cross-sectional area of the yielding core increases, and, consequently, that of the axial stress has been reduced.

#### 4.4. Influence of the Inclination of the BRD on the Axial Stress of the Damaged Members

## 5. Conclusive Remarks

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## References

- Jun-ichi, H.; Guangfeng, Z. Performance of seismic retrofitted highway bridges based on observation of damage due to the 2011 Great East Japan Earthquake. J. JSCE
**2013**, 1, 343–352. [Google Scholar] [CrossRef] - Kawashima, K.; Unjoh, S. Seismic design of highway bridges. J. Japan Assoc. Earthq. Eng.
**2004**, 4, 283–297. [Google Scholar] [CrossRef] - Symans, M.D.; Charney, F.A.; Whittaker, A.S.; Constantinou, M.C.; Kircher, C.A.; Johnson, M.W.; McNamara, R.J. Energy dissipation systems for seismic applications: current practice and recent developments. J. Struct. Eng.
**2008**, 134, 3–21. [Google Scholar] [CrossRef] - Takeuchi, T.; Wada, A. Buckling Restrained Braces and Applications, 1st ed.; in English; The Japan Society of Seismic Isolation: Tokyo, Japan, 2017; pp. 3–5. [Google Scholar]
- Usami, T. A new seismic performance upgrading method for existing steel bridges using BRBs. In Proceedings of the SECED Earthquake Risk and Engineering towards a Resilient World, Cambridge, UK, 9–10 July 2015. [Google Scholar]
- Usami, T.; Lu, Z.; Ge, H. A seismic upgrading method for steel arch bridges using buckling-restrained braces. Earthquake Engng Struct. Dyn.
**2005**, 34, 471–496. [Google Scholar] [CrossRef] - Hoveidae, N.; Tremblay, R.; Rafezy, B.; Davaran, A. Numerical investigation of seismic behavior of short-core all-steel buckling restrained braces. J. Constr. Steel Res.
**2015**, 114, 89–99. [Google Scholar] [CrossRef] - Mirtaheri, M.; Gheidi, A.; Zandi, A.P.; Alanjari, P.; Samani, H.R. Experimental optimization studies on steel core lengths in buckling restrained braces. J. Constr. Steel Res.
**2011**, 67, 1244–1253. [Google Scholar] [CrossRef] - Muhamed, P.; Sahoo, D.R. Cyclic testing of short-length buckling-restrained braces with detachable casings. Earthq. Struct.
**2016**, 10, 699–716. [Google Scholar] [CrossRef] - Razavi Tabatabaei, S.A.; Mirghaderi, S.R.; Hosseini, A. Experimental and numerical developing of reduced length buckling-restrained braces. Eng. Struct.
**2014**, 77, 143–160. [Google Scholar] [CrossRef] - Tsai, K.; Lai, J.; Hwang, Y.; Lin, S.; Weng, C. Research and application of double-core buckling restrained braces in Taiwan. In Proceedings of the 13th World Conference on Earthquake Engineering, Vancouver, BC, Canada, 1–6 August 2004. [Google Scholar]
- Abaqus/CAE Ver. 6.13. User’s Manual; Dassault Systems Simulia Corp.: Providence, RI, USA, 2013. [Google Scholar]
- Goto, Y.; Kawanishi, N.; Honda, I. On impacts caused by sudden failure of diagonal tension members in steel truss bridges. J. Struct. Eng.
**2010**, 56A, 792–805. [Google Scholar] - Chopra, A.K. Dynamics of Structures: theory and applications to earthquake engineering, 4th ed.; Prentice Hall: London, UK, 2013. [Google Scholar]
- Japan Society of Civil Engineers. Standard Specifications for Steel and Composite Structures, First Edition, I General Provision, II Structural Planning, III Design, 2009. Available online: http://www.jsce-int.org/system/files/Standard.pdf (accessed on 21 October 2010).
- Japan Road Association, Technical data. Available online: https://www.road.or.jp/dl/tech.html (accessed on 2 March 2012).
- J.R. Association. Design Specifications for Highway Bridges, Part V Seismic Design. 2002. Available online: http://iisee.kenken.go.jp/worldlist/29_Japan/29_Japan_2_HighwayBridge_Code_2002_01.pdf (accessed on 1 September 2002).

**Figure 5.**Deformation patterns of the truss bridge due to (

**a**) dead-load; (

**b**) the large earthquake in compressive direction; (

**c**) the large earthquake in tensile direction.

Name Description of Members | Location between the Nodes Numbered in Figure 2 | Cross Section | Web (mm) | Flange (mm) | Steel Grade |
---|---|---|---|---|---|

Lower chord | 1–5, 21–25, 2–6, 22–26 | 430 × 9 | 450 × 10 | SM400 | |

5–9, 17–21, 6–10, 18–22 | 412 × 22 | 450 × 19 | SM490Y | ||

9–17, 10–18 | 400 × 25 | 450 × 25 | SM490Y | ||

Upper chord | 27–33, 45–51, 28–34, 46–52 | 518 × 14 | 450 × 16 | SM490Y | |

33–37, 41–45, 34–38, 42–46 | 506 × 19 | 450 × 22 | SM490Y | ||

37–41, 38–42 | 502 × 21 | 450 × 24 | SM490Y | ||

Inclined post | 1–29, 49–25, 2–30, 50–26 | 412 × 28 | 400 × 19 | SM490Y | |

5–33, 45–21, 6–34, 46–22 | 418 × 22 | 400 × 16 | SM400 | ||

9–37, 41–17, 10–38, 42–18 | 430 × 13 | 400 × 10 | SM400 | ||

End vertical | 1–27, 2–28, 25–51, 26–52 | 430 × 13 | 400 × 10 | SM400 | |

Inclined post | 29–5, 21–49, 30–6, 22–50 | 422 × 14 | 350 × 14 | SM490Y | |

37–13, 13–41, 38–14, 14–42 | 430 × 11 | 350 × 10 | SM400 | ||

33–9, 17–45, 34–10, 18–46 | 422 × 12 | 350 × 14 | SM400 | ||

Inner vertical | 5–31, 6–32, and etc. | 422 × 12 | 350 × 14 | SM400 | |

Outer vertical brace | 25–52, 26–51, 1–28, 2–27 | 318 × 16 | 350 × 16 | SM400 | |

Upper lateral bracing | 27–30, 28–29, and etc. | 138 × 10 | 350 × 14 | SM400 | |

Lower lateral bracing | 1–4, 2–3, and etc. | 180 × 10 | 200 × 10 | SM400 | |

Floor beam | 27–28, 39–30, and etc. | 1068 × 10 | 350 × 16 | SM400 | |

Outer strut | 1–2, 25–26 | 424 × 10 | 400 × 13 | SM400 | |

Inner strut | 3–4, 5–6, and etc. | 230 × 10 | 250 × 10 | SM400 | |

Inner vertical brace | 5–31, 6–32, 22–48, and etc. | 140 × 16 | 250 × 10 | SM400 |

Damaged Members * | Axial Stress, ${\mathit{\sigma}}_{\mathit{i}\mathit{d}\mathit{m}}$ (N/mm^{2}) | R_{c} | R_{t} | |
---|---|---|---|---|

Min. | Max. | |||

1–3; 3–5; 2–4; 4–6 | −252.79 | 251.83 | 1.305 | 1.072 |

Model | $\mathbf{Axial}\text{}\mathbf{Stress},\text{}{\mathit{\sigma}}_{\mathit{i}\mathit{d}\mathit{m}}\text{}(\mathbf{N}/{\mathbf{mm}}^{2})$ | R_{c} | R_{t} | |||
---|---|---|---|---|---|---|

Min. | Reduction by BRD | Max. | Reduction by BRD | |||

Initial model | −252.795 | - | 251.830 | - | 1.305 | 1.072 |

L-10.5-5-0° | −189.083 | 25.2% | 238.879 | 5.1% | 0.976 | 1.017 |

L-10.5-10-0° | −207.537 | 17.9% | 237.994 | 5.5% | 1.071 | 1.013 |

L-10.5-20-0° | −165.261 | 34.6% | 237.668 | 5.6% | 0.853 | 1.011 |

L-10.5-30-0° | −100.729 | 60.2% | 235.763 | 6.4% | 0.520 | 1.003 |

L-10.5-40-0° | −80.886 | 68.0% | 217.084 | 13.8% | 0.418 | 0.924 |

L-7.0-5-0° | −193.986 | 23.3% | 238.681 | 5.2% | 1.001 | 1.016 |

L-7.0-10-0° | −167.945 | 33.6% | 238.228 | 5.4% | 0.867 | 1.014 |

L-7.0-20-0° | −99.704 | 60.6% | 236.315 | 6.2% | 0.515 | 1.006 |

L-7.0-30-0° | −77.834 | 69.2% | 207.515 | 17.6% | 0.402 | 0.883 |

L-7.0-40-0° | −70.642 | 72.1% | 198.125 | 21.3% | 0.365 | 0.843 |

L-3.5-5-0° | −190.793 | 24.5% | 237.748 | 5.6% | 0.985 | 1.012 |

L-3.5-10-0° | −140.195 | 44.5% | 236.026 | 6.3% | 0.724 | 1.004 |

L-3.5-20-0° | −70.343 | 72.2% | 195.143 | 22.5% | 0.363 | 0.830 |

L-3.5-30-0° | −64.069 | 74.7% | 183.292 | 27.2% | 0.331 | 0.780 |

L-3.5-40-0° | −59.115 | 76.6% | 167.083 | 33.7% | 0.305 | 0.711 |

L-1.75-5-0° | −121.362 | 52.0% | 236.561 | 6.1% | 0.626 | 1.007 |

L-1.75-10-0° | −108.312 | 57.2% | 235.380 | 6.5% | 0.559 | 1.002 |

L-1.75-20-0° | -83.310 | 67.0% | 213.966 | 15.0% | 0.430 | 0.910 |

L-1.75-30-0° | −60.885 | 75.9% | 170.123 | 32.4% | 0.314 | 0.724 |

L-1.75-40-0° | −54.691 | 78.4% | 146.279 | 41.9% | 0.282 | 0.622 |

Model | $\mathbf{Axial}\text{}\mathbf{Stress},\text{}{\mathit{\sigma}}_{\mathit{i}\mathit{d}\mathit{m}}\text{}(\mathbf{N}/{\mathbf{mm}}^{2})$ | R_{c} | R_{t} | |||
---|---|---|---|---|---|---|

Min. | Reduction by BRD | Max. | Reduction by BRD | |||

Initial model | −252.795 | - | 251.830 | - | 1.305 | 1.072 |

R-10.5-5-0° | −235.912 | 6.7% | 240.905 | 4.3% | 1.218 | 1.025 |

R-10.5-10-0° | −239.067 | 5.4% | 240.389 | 4.5% | 1.234 | 1.023 |

R-10.5-20-0° | −237.529 | 6.0% | 239.175 | 5.0% | 1.226 | 1.018 |

R-10.5-30-0° | −153.764 | 39.2% | 238.217 | 5.4% | 0.794 | 1.014 |

R-10.5-40-0° | −117.468 | 53.5% | 236.847 | 5.9% | 0.606 | 1.008 |

R-7.0-5-0° | −220.056 | 13.0% | 240.025 | 4.7% | 1.136 | 1.021 |

R-7.0-10-0° | −223.142 | 11.7% | 239.199 | 5.0% | 1.152 | 1.018 |

R-7.0-20-0° | −150.093 | 40.6% | 238.024 | 5.5% | 0.775 | 1.013 |

R-7.0-30-0° | −136.510 | 46.0% | 237.408 | 5.7% | 0.705 | 1.010 |

R-7.0-40-0° | −151.054 | 40.2% | 237.069 | 5.9% | 0.780 | 1.009 |

R-3.5-5-0° | −172.310 | 31.8% | 237.874 | 5.5% | 0.889 | 1.012 |

R-3.5-10-0° | −134.188 | 46.9% | 236.987 | 5.9% | 0.693 | 1.008 |

R-3.5-20-0° | −138.902 | 45.1% | 237.070 | 5.9% | 0.717 | 1.009 |

R-3.5-30-0° | −145.477 | 42.5% | 237.050 | 5.9% | 0.751 | 1.009 |

R-3.5-40-0° | −108.009 | 57.3% | 235.851 | 6.3% | 0.558 | 1.004 |

R-1.75-5-0° | −119.326 | 52.8% | 236.007 | 6.3% | 0.616 | 1.004 |

R-1.75-10-0° | −111.509 | 55.9% | 236.355 | 6.1% | 0.576 | 1.006 |

R-1.75-20-0° | −115.749 | 54.2% | 237.034 | 5.9% | 0.597 | 1.009 |

R-1.75-30-0° | −96.659 | 61.8% | 236.300 | 6.2% | 0.499 | 1.006 |

R-1.75-40-0° | −100.609 | 60.2% | 236.300 | 6.2% | 0.519 | 1.006 |

Model | The Safety Condition | Horizontal Displacement at the Moveable End of the Damaged Members (mm) | ||||
---|---|---|---|---|---|---|

R_{c} | R_{t} | Min. | Reduction by BRD | Min. | Reduction by BRD | |

Initial model | 1.305 | 1.072 | −8.468 | - | 67.525 | - |

L-1.75-20-0° | 0.430 | 0.910 | −3.444 | 59.3% | 5.644 | 91.6% |

R-1.75-20-0° | 0.597 | 1.009 | −7.083 | 16.4% | 11.483 | 83.0% |

**Table 6.**Influence of the length of the BRD yielding core on the horizontal displacement due to the earthquake.

Model | The Safety Condition | Horizontal Displacement at the Moveable End of the Damaged Members (mm) | ||||
---|---|---|---|---|---|---|

R_{c} | R_{t} | Min. | Reduction by BRD | Min. | Reduction by BRD | |

Initial model | 1.305 | 1.072 | −8.468 | - | 67.525 | - |

L-10.5-20-0° | 0.853 | 1.011 | −9.097 | −7.4% | 16.942 | 74.9% |

L- 7.0 -20-0° | 0.515 | 1.006 | −8.909 | −5.2% | 8.549 | 87.3% |

L- 3.5 -20-0° | 0.363 | 0.830 | −5.865 | 30.7% | 4.671 | 93.1% |

L-1.75-20-0° | 0.430 | 0.910 | −3.444 | 59.3% | 5.644 | 91.6% |

**Table 7.**Influence of the cross-sectional area of the BRD yielding core on the horizontal displacement due to the earthquake.

Model | The Safety Condition | Horizontal Displacement at the Moveable End of the Damaged Members (mm) | ||||
---|---|---|---|---|---|---|

R_{c} | R_{t} | Min. | Reduction by BRD | Min. | Reduction by BRD | |

Initial model | 1.305 | 1.072 | −8.468 | - | 67.525 | - |

L-3.5-5-0° | 0.985 | 1.012 | −14.473 | −70.9% | 19.177 | 71.6% |

L-3.5-10-0° | 0.724 | 1.004 | −7.867 | 7.1% | 10.218 | 84.9% |

L-3.5-20-0° | 0.363 | 0.830 | −5.865 | 30.7% | 4.671 | 93.1% |

L-3.5-30-0° | 0.331 | 0.780 | −3.463 | 59.1% | 3.695 | 94.5% |

L-3.5-40-0° | 0.305 | 0.711 | −2.588 | 69.4% | 2.827 | 95.8% |

Model | $\mathbf{Axial}\text{}\mathbf{Stress},\text{}{\mathit{\sigma}}_{\mathit{i}\mathit{d}\mathit{m}}\text{}(\mathbf{N}/{\mathbf{mm}}^{2})$ | R_{c} | R_{t} | |||
---|---|---|---|---|---|---|

Min. | Reduction by BRD | Max. | Reduction by BRD | |||

Initial model | −252.795 | - | 251.830 | - | 1.305 | 1.072 |

L-3.5-20 - 0° | −70.343 | 72.2% | 195.143 | 22.5% | 0.363 | 0.830 |

L-3.5-20 - 5° | −66.839 | 73.6% | 236.677 | 6.02% | 0.345 | 1.007 |

L-3.5-20-10° | −139.010 | 45.0% | 236.794 | 5.97% | 0.718 | 1.008 |

L-3.5-20-15° | −93.184 | 63.1% | 235.561 | 6.46% | 0.481 | 1.002 |

R-3.5-20 - 0° | −138.902 | 45.1% | 237.070 | 5.9% | 0.717 | 1.009 |

R-3.5-20 - 5° | −162.732 | 35.6% | 238.163 | 5.4% | 0.840 | 1.013 |

R-3.5-20-10° | −88.673 | 64.9% | 235.228 | 6.6% | 0.231 | 1.001 |

R-3.5-20-15° | −66.839 | 73.6% | 236.677 | 6.0% | 0.345 | 1.007 |

Model | The safety condition | Horizontal Displacement at the Moveable End of the Damaged Members (mm) | ||||
---|---|---|---|---|---|---|

${\mathbf{R}}_{\mathbf{c}}$ | ${\mathbf{R}}_{\mathbf{t}}$ | Min. | Reduction by BRD | Min. | Reduction by BRD | |

Initial model | 1.305 | 1.072 | −8.468 | - | 67.525 | - |

L-3.5-20 - 0° | 0.363 | 0.830 | −5.865 | 30.7% | 4.671 | 93.1% |

L-3.5-20 - 5° | 0.345 | 1.007 | −6.106 | 27.9% | 5.607 | 91.7% |

L-3.5-20-10° | 0.718 | 1.008 | −7.585 | 10.4% | 8.919 | 86.8% |

L-3.5-20-15° | 0.481 | 1.002 | −9.595 | −13.3% | 10.922 | 83.8% |

R-3.5-20 - 0° | 0.717 | 1.009 | −3.787 | 55.3% | 7.462 | 88.9% |

R-3.5-20 - 5° | 0.840 | 1.013 | −5.488 | 35.2% | 4.370 | 93.5% |

R-3.5-20-10° | 0.231 | 1.001 | −6.900 | 18.5% | 6.121 | 90.9% |

R-3.5-20-15° | 0.345 | 1.007 | −8.765 | −3.5% | 8.978 | 86.7% |

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**MDPI and ACS Style**

Sosorburam, P.; Yamaguchi, E.
Seismic Retrofit of Steel Truss Bridge Using Buckling Restrained Damper. *Appl. Sci.* **2019**, *9*, 2791.
https://doi.org/10.3390/app9142791

**AMA Style**

Sosorburam P, Yamaguchi E.
Seismic Retrofit of Steel Truss Bridge Using Buckling Restrained Damper. *Applied Sciences*. 2019; 9(14):2791.
https://doi.org/10.3390/app9142791

**Chicago/Turabian Style**

Sosorburam, Purevdorj, and Eiki Yamaguchi.
2019. "Seismic Retrofit of Steel Truss Bridge Using Buckling Restrained Damper" *Applied Sciences* 9, no. 14: 2791.
https://doi.org/10.3390/app9142791