Transient responses of repeated impact of a beam against a stop

Advances in Structural Engineering

Hao

et al. 2015

Vertical earthquake loading is normally regarded not as important as its horizontal components and are not explicitly considered in many seismic design codes. However, some previous severe near-fault earthquakes reveal that the vertical ground motion component can be much larger than the horizontal components and may cause serious damage to the bridge structures. This paper theoretically investigates the vertical pounding responses of a two-span continuous bridge subjected to the severe near-fault vertical ground motions. The bridge is simplified as a continuous beam-spring-rod model. The structural wave effect and the vertical pounding between the bridge girder and the supporting bearing are considered, and the theoretical solutions of bridge seismic responses are derived from the expansion of transient wave functions as a series of eigenfunctions. The effects of vertical earthquake and vertical pounding on the bridge bearing, girder and pier are investigated. The numerical results show that the severe vertical earthquake loading may cause the bridge girder to separate from the supporting bearing and hence result in vertical poundings between them when they are in contact again. These vertical poundings can significantly alter the seismic responses of the bridge structure and may cause severe damage to the bridge components such as bridge girder, supporting bearing and bridge pier. Neglecting the influence of vertical earthquake loading may lead to inaccurate estimation of seismic responses of bridge structures, especially when they are subjected to near-fault earthquake with relatively large vertical motion.

Section: Solutions Of Seismic Responses In the Pounding Phasementioning

confidence: 99%

“…The similar method has been used successfully in solving the multiple-impact problems of two coaxial hollow cylinders (Yin 1997;Yin and Wang 1999;Yin and Yue 2002) and the repeated-impact problem between a cantilever beam and a rod (Yin et al 2007). …”

Section: Solutions Of the Multiple Pounding Forcementioning

confidence: 99%

Theoretical Investigation of Bridge Seismic Responses with Pounding under Near-Fault Vertical Ground Motions

Yang

Advances in Structural Engineering

Hao

et al. 2015

“…In this section, the transient responses of bridge are solved by the use of the expansion of transient wave functions in a series of eigenfunctions (i.e. wave modes) .…”

Section: Solutionsmentioning

confidence: 99%

Transient responses of girder bridges with vertical poundings under near‐fault vertical earthquake

Yang

Earthq Engng Struct Dyn

2015

SUMMARYPrevious studies on pounding responses of bridge structures mainly focus on the horizontal pounding between adjacent structures. However, the vertical pounding responses of bridge are rarely studied. The aim of this paper is develop a theoretical approach to investigate the transient behavior of continuous bridge under near-fault vertical ground motions. The transient behavior of bridge manifests as the earthquake-induced response wave and pounding-induced response wave travel throughout bridge. Based on a new continuous model of beam-spring-rod, the theoretical solution of bridge responses involving multiple vertical poundings is derived by the expansion of transient wave functions in a series of eigenfunctions. A new theoretical solving approach of the multiple vertical pounding forces is presented based on the transient internal force on the contact surface of the girder and bearing. The numerical results show that the present method can reasonably capture the propagations of the earthquake-induced response wave and pounding-induced response wave. The calculations of pounding force by the present method are convergence of the time-step size and truncation number of wave modes. As the effect of transient wave is taken into account, the numerical results show several transient phenomena involving the vertical pounding, the high pounding force, the multiple-pounding phenomenon, the vertical separation of girder from the bearing, the dependence of poundings on earthquake period and the narrow period window of poundings.

“…The repeated contact-impact or/and the repeated friction between the impact drive mechanism (IDM) and the object body are common driving manners of the object body to cumulate micro-displacement and power. The repeated impact [5] , the piezoelectric driving [6][7][8] and the repeated friction will excite the transient waves travelling throughout the connecting flexible components, making the systematic mechanical behaviors complicated and largely influencing the positioning accuracy [9] . The poorly controlled repeated impacts and repeated frictions could bring the system abnormal vibration, lower positioning accuracy and even out of the control.…”

Section: Introductionmentioning

confidence: 99%

Dynamic substructure model for multiple impact responses of micro/nano piezoelectric precision drive system

Shen

Sci. China Ser. E-Technol. Sci.

2009

A dynamic substructure technique which considers the electromechanical coupling effect of the PZT and the inertial effect of flexible components is presented to study the multiple impact dynamic behavior of micro/nano piezoelectric impact drive systems. It can investigate the step-like motion of object body and the multiple impacts behaviors reasonably by the comparison of the experimental data and the numerical solution of the spring-mass model. It is expected to have higher accuracy in the numerical simulations of the motion and the responses, especially to high frequency pulse voltage excitations. The present dynamic substructure technique has firstly studied reasonably the propagations of piezoelectric-induced transient waves and impact-induced transient waves. It is helpful to the failure analysis and the design of piezoelectric stack and flexible components. The present dynamic substructure technique can be applied to the transient dynamics optimization design and the precision control of the micro/nano piezoelectric impact drive systems.piezoelectric micro actuator, multiple impacts, dynamic substructure technique, electromechanical coupling, transient wave propagation, precision positioning