Performance of seismic‐isolated bridges with and without elastic‐gap devices in near‐fault zones

Dicleli, Murat

doi:10.1002/eqe.797

Cited by 19 publications

(8 citation statements)

References 19 publications

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“…For structures subjected to earthquakes with intense long duration acceleration pulses, although seismic isolation technology may be used to reduce and control the magnitude of the forces, such a system alone may not be adequate to reduce the displacement demand to practical ranges of application [1]. In such cases, a combination of seismic isolation and dampers is used to reduce and control both forces and displacements.…”

Section: Introductionmentioning

confidence: 99%

Systematic development of a new hysteretic damper based on torsional yielding: part I—design and development

Milani

Dicleli

2015

Earthq Engng Struct Dyn

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Analytical and experimental studies into the behavior of a new hysteretic damper, designed for seismic protection of structures is presented in two papers. Although the subject matter of the papers is a specific system, they are also intended as an illustration of practical application of diverse engineering tools in systematic development of an anti-seismic product. The Multi-directional Torsional Hysteretic Damper (MTHD) is a recently patented invention in which a symmetrical arrangement of identical cylindrical steel energy dissipaters is configured to yield in torsion while the structure experiences planar movements due to earthquake shakings. The device has gone through many stages of design refinement, prototype verification tests and development of design guidelines and computer codes to facilitate its implementation in practice. The first of this two-part paper summarizes the development stages of the new system, conceptual and analytical. The experimental phase of the research is the focus of the accompanying paper. The new device has certain desirable properties. Notably, it is characterized by a variable and controllable-via-design or adaptive post-elastic stiffness. This feature gives the isolated structure the capability to evade the dominant period of the ground motion leading to reduced displacements while having force levels comparable to regular bilinear isolation systems. The device has already been applied to four major bridges.The appropriate numerical solution procedure of the above equations depends on the form and nature of torque-twist angle (T-θ) relationships, which will be discussed in Section 6. 850 A. SALEM MILANI AND M. DICLELI Figure 10. Displacement-dependent variation in tangent stiffness-based period of an isolated structure equipped with MTHD + sliding bearings (μ = 0.01), in case of a typical MTHD with (a) HI = 1.5; (b) HI = 2.0. 858 A. SALEM MILANI AND M. DICLELI Figure 12. Effect of displacement direction in MTHD: (a) angle, α to characterize the orientation of the imposed displacement relative to the configuration of the EDs, (b),(c): properties of the MTHD versus angle α.860 A. SALEM MILANI AND M. DICLELI Figure 13. (a) FE model. Distribution of plastic strain in peripheral elements over the height of the ED (along the uniform part) at increasing twist angles (θ): (b) E t /E = 0.0002 (nearly elasto-plastic) with the presence of bending, (c) E t /E = 0.002 with the presence of bending, (d) E t /E = 0.002 with pure torsion (no bending)

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Section: Introductionmentioning

confidence: 99%

Systematic development of a new hysteretic damper based on torsional yielding: part I—design and development

Milani

Dicleli

2015

Earthq Engng Struct Dyn

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“…Large pulses and permanent displacements are characteristic for near‐fault ground motion and as such, strong shaking close to earthquake sources can be completely different from far‐field motions. It has been shown that when an earthquake fault is near, structural responses are noticeably affected by the amplitude and period of the velocity pulses 33–38 . It has also been shown that consideration of the ground‐motion vertical component in the design of highway bridges, particularly those near faults, is important 39,40 .…”

Section: Introductionmentioning

confidence: 99%

Near‐fault ground motion effects on pounding and unseating using an example of a three‐span, simply supported bridge

Khakzand

Jalali

Veisi

2022

Earthquake Engineering and Resilience

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A simple model of a three-span, simply supported bridge consisting of three rigid decks supported by two axially rigid piers and rigid abutments at two ends is analyzed by solving the dynamic differential equations. The response spectrum method is not considered, and it is assumed that there is no soil-structure interaction. The bridge is acted upon by the acceleration of gravity, g, and excited by differential horizontal-, vertical-, and point-and cord-rocking components of nearfault ground motion. The model's in-plane linear response shows that the vertical and rocking ground-motion components have no noticeable effect on the maximum pounding force between bridge segments when computed for horizontal ground motion only. For the model with system periods longer than 1 s subjected to the strong motion pulse corresponding to magnitude M = 7, the vertical groundmotion component contributes to the destabilizing effect of the gravity. For bridge periods longer than 0.5 s, the simultaneous action of horizontal and vertical groundmotion components can noticeably increase the minimum gap size required to prevent pounding and the minimum seating length to avoid the unseating of bridge segments when computed for horizontal ground motion only. For system periods shorter than 1 s, the time delay of input ground motion has a significant effect on the minimum gap size to prevent pounding as well as on the minimum seating length to avoid unseating of the deck. The response of the bridge subjected to differential horizontal, vertical, and point-rocking ground-motion components is almost the same as the response under differential horizontal and vertical components of the ground motion. The main contribution to changes in the response, which is computed for horizontal ground motion only, is caused by the vertical and cord rocking of the ground motion. The minimum seating length to avoid the unseating of bridge segments suggested in seismic Iranian Code, No: 463 (Road and railway bridges seismic-resistant design code, 2008), is conservative for pulses with magnitudes M = 5 and 6, but not conservative for bridge periods longer than about 0.6 s and a near-field pulse with M = 7 magnitude.

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“…Collision shear walls have been found to be effective in reducing the consequences of pounding (Anagnostopoulos and Karamaneas, [5]). Elastic gap devices (see, for example, Dicleli, [6]), have been shown to be effective in mitigating damage caused by pounding.…”

Section: Introductionmentioning

confidence: 99%

Shared Tuned Mass Dampers for Mitigation of Seismic Pounding

2020

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This study explores the effectiveness of shared tuned mass damper (STMD) in reducing seismic pounding of adjacent buildings. The dynamics of STMDs is explored through numerical simulations of buildings idealized as single and multiple degree of freedom oscillators. An optimization method proposed in the literature is revisited. It is shown that the optimization results in two different solutions. The first one corresponds to the device being tuned to one of the buildings it is attached to. The second solution corresponds to a very stiff system where the TMD mass hardly moves. This solution, which has been described as an STMD in the literature, is shown to be impractical due to its high stiffness and use of a heavy stationary mass that plays no role in response mitigation but adds unnecessary load to the structure. Furthermore, it is shown that the second solution is equivalent to a viscous coupling of the two buildings. As for the properly tuned solution, i.e., the first solution, sharing the device with an adjacent building was found to provide no added benefits compared to when it is placed on one of the buildings. Based on results from a large set of real earthquake ground motions, it is shown that sharing a TMD mass with an adjacent building, in contrary to what is reported in the literature, is not an effective strategy.

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Performance of seismic‐isolated bridges with and without elastic‐gap devices in near‐fault zones

Cited by 19 publications

References 19 publications

Systematic development of a new hysteretic damper based on torsional yielding: part I—design and development

Systematic development of a new hysteretic damper based on torsional yielding: part I—design and development

Near‐fault ground motion effects on pounding and unseating using an example of a three‐span, simply supported bridge

Shared Tuned Mass Dampers for Mitigation of Seismic Pounding

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