Gravity effects on the earthquake response of yielding structures
The effect of gravity on the earthquake response of one degree of freedom yielding structures is studied by subjecting them to earthquake-like excitation. Interest is centered on the time required for yielding to progress to the point of collapse. The results show that the effect of gravity is to in...
| Summary: | The effect of gravity on the earthquake response of one degree of freedom yielding structures is studied by subjecting them to earthquake-like excitation. Interest is centered on the time required for yielding to progress to the point of collapse. The results show that the effect of gravity is to increase significantly the development of permanent set over that occurring when gravity is ignored. Because the gravity effect increases as the deflection grows, the permanent set increases rapidly just prior to failure.
A statistical study of the time to failure for elasto-plastic structures indicates that the average time to failure is inversely proportional to the square of the ratio of the earthquake strength to the lateral yield level of the structure, implying that an earthquake of short duration would have to possess significantly higher accelerations than a longer earthquake in order to cause failure of a given structure.
It was found that for the range of periods considered the average time to collapse for the yielding structures was independent of period. For the bilinear hysteretic structure the results show a large increase in the time of failure when the second slope increases from zero.
Calculations made with simultaneous vertical and horizontal excitation, and with recorded strong earthquake accelerograms, indicate that the thesis results, obtained from artificial earthquakes, should be applicable for strong earthquake excitation.
Comparison of the results with those of a one-dimensional random walk indicates that on the average a yielding structure will collapse after the input of a certain amount of energy. |
|---|