On Predictions and Performance of Machine Foundations

A model for predicting the amplitude versus frequency response for surface footings under vibrations is presented. The model considers the effects of soil nonlinearity and confining pressures on soil modulus and has been verified by comparing model predictions with performance field tests. The elastic half space analog solutions have been used to develop a computer program for this prediction model (Manyando, 1990). Soil nonlinearity has been accounted for by incorporating an iterative procedure in the computer program. The computer program was used to predict the footing response in vertical, torsional and coupled rocking and sliding vibrations. Predicted resonant amplitudes, resonant frequencies and the total sweeps have been compared with the measured values. It has been found that predictions by this model closely match the measured data. Vertical and coupled rocking and sliding vibrations predictions closely match measured data when material damping is neglected. Predictions for torsional vibrations are observed to be satisfactory when 10 percent material damping is used and the slip at the base of the footing is neglected

Vibration Mitigation for Brewery Stockhouse Demolition

Nineteen thirty\u27s vintage reinforced concrete brewery stockhouses, collectively known as Borsari Cellars, were demolished to make space for the construction of a new stockhouse. (A brewery stockhouse is a refrigerated building containing beer storage or aging tanks.) The stockhouses to be demolished shared three common walls with two other stockhouses which were to remain intact during the demolition. It was necessary that the three shared walls remain attached to the remaining stockhouses and that the demolition take place without causing vibration damage to glass-lined tanks in the remaining stockhouse, adjacent stockhouscs, and to several underground tunnels present below the demolition site. The following tasks were performed to successfully complete this project: (I) design and install a rock-anchored tie-back system for retaining the three shared walls: (2) evaluate ambient ground vibrations during normal business activities in the subject stockhouscs and general project area: (3) recommend an allowable demolition vibration criteria and develop a monitoring program; and (4) implement the monitoring program. A resultant peak particle velocity (RPPV) of 1.0 inch per second was recommended as the threshold for low-risk demolition. This program was used successfully to demolish the Borsari Cellars without causing damage to adjacent stockhouses, glass-lined beer tanks, and underground tunnels on the project site. This approach could be used for similar situations or for demolition in areas where industrial buildings with sensitive equipment are in close proximity