Abstract
Remarkable and vigorous progress has been made in recent years in theoretical studies on aseismatic structural engineering, especially studies on response analysis of structure under seismic loading. On the other hand, experimental studies on dynamic failure of materials or members of structure has just started, and it seems to be lagging behind the former. The reason has been simpley that we were not able to possess a suitable dynamic loading machine to test the structural members. While our study regarding automatic load control for making the most suitable dynamic loading machine to test structural members continues, we wish to summarize the results of our studies achieved so far. It is desirable that the testing machine should be able to give irregular waves of load to test the structural members under seismic load. To satisfy this condition, a testing machine driven by electrohydraulic servo mechanism is perhaps the most suitable. This type of testing machine, which has an electrohydraulic servo valve, utilizes an automatic load control system, whereby the machine regenerates irregular waves of load for any desired load programme, when electric signals are given. But to test the structural members, several dozen tons of load capacity and about 10 cycles/sec of loading rate are necessary. Ordinary servo valves are far insufficient in out-flow-rate to meet these requirements. In this study, to increase the out-flow rate of the system, we adopted a sort of 2 stage hydraulic system whose first stage is operated by an ordinary servo valve, and suceeded in incressing its out-flow rate 10 times or more. Moreover, we deviced an apparatus of high-performance ability and highspeed loading rate by means of arranging several large accumulators in series. This report (original) describes also the progress of projecting the machine system, determination of proportioning, explanations of various elements of machine and the results of some tests conducted after the machine had been completed.
