The Analysis On Dynamic Response Of Single Pipe Pile Based On Shaking Table Model Test

With the development of China’s economic construction, more and morearchitectural forms begin to appear, and the geological conditions of the buildings arealso more and more complex. Prestressed concrete pipe pile (PHC) is increasinglypopular because its reliable pile-forming, low cost, good compressive property andflexural performance. However, several large earthquakes in recent years werewake-up calls to the seismic design, especially for the seismic design of the buildingfoundations. So far, the research and specification about the foundation design are less,it’s difficult to find the exact basis from the design of the PHC and the seismicproblems. In this paper, the strain response of the single pile under differentconditions from the experiment design and operation, and the pile internal forcesthrough theoretical derivation were obtained. The internal force distribution law ofsingle pile under different loading ways and vibration forces was summarized fromcombining the experimental data. Thus, the law could provide the later seismic designof PHC with some experimental support.Contrasting conditions experiment was used to design test conditions in thispaper, including different loading ways, divided into dynamic and static load, andexcitation waveforms. Dynamic load was the table shaking test, simulating the effectof seismic action on single pile, which obtained the different working conditionsthrough changing the acceleration wave peak and wave frequency. While the workingconditions of static load were adjusted by changing loading strength.Among the test, the initial strain data of single pile was obtained with simulatingthe response of single pile-earth-upper structure under different conditions. Thedistributions of pile bending moment, shearing force, axial force, load anddisplacement, through data processing, were derived.Through this single pile shaking table simulation test, the following results couldapproximately be obtained:(1) The strain of the single pile along the pile was generated by the bendingstrain of bending moments, together with the axial strain for the additional axial force.Analyzing the data showed that the stress of upper part of the single pile (from the top of the pile depth of more than600mm) was mainly to bending, while the lower part(from the top of the pile depth of less than600mm) was mainly to axial force.(2) The distribution shapes of the strain, bending moment, shearing force andaxial force of the single pile along the pile were obtained under different conditions ofshaking table test. The distribution shapes were in the same, respectively, and havenothing to do with the working conditions. Meanwhile, the maximum point of eachinternal force was gotten.(3) Under different conditions, the strain and internal force strength along thepile of single pile in the earthquake varied with the excitation force. If the vibrationwaveform frequency was same, the acceleration wave peak would promote eachreaction of single pile. If the acceleration wave peak was in common, the reaction ofsingle pile was related to the approximation degrees of vibration wave frequency andnatural vibration frequency of the upper structure.(4) Load and displacement distribution shapes of single pile along pile had nodifference, but the magnitude was related to loading ways and vibration waveforms.(5) In the same conditions, the maximum dynamic shear and static load of toppile was same, the reaction shapes of single pile under dynamic load and static loadwere in common. However, reaction strength of single pile under static load wasmuch less than single pile under dynamic load.