Vibration analysis of foundations subjected to pulse excitations with negative phase
- Vol.52(5), Oct
- USA Springer 2022
- 1065-1078p.
Analysis of a hammer foundation subjected to combined action of rectangular pulse due to its operation and exponential pulse excitation with negative phase in an event of explosion is carried out in this study. The foundation is considered to be a one-mass foundation and the soil-foundation system is modeled as elastic single degree of freedom (SDOF) system. Based on time duration of rectangular pulse loading and time of arrival of exponential pulse excitation, four cases of analysis are considered. For each case, closed-form solutions are derived for underdamped system using analytical approach considering the interaction of two different types of pulse loading namely (i) rectangular pulse, and (ii) exponential pulse having positive and negative phases. A detailed parametric study is carried out to understand the influence of various input parameters on time-displacement history of the system for all the four cases. These parameters include mass and stiffness of machine-foundation system, damping ratio, magnitude of pulse loadings, and wave decay parameter for exponential pulse excitation. The peak responses are found to reduce to an extent of about 68% when stiffness of the soil-foundation system is increased from 250 to 1000 kN/mm. The maximum response is found to occur for wave decay parameter as 0.6. Other parameters also have significant influence on the response of the system. This study finds application in the design of hammer foundations under simultaneous impact (rectangular) and exponential pulse excitations.