The self-reaction frame is used in two situations. One is that there is no reaction foundation where you want to install the load frame. Another is the maximum load exceeds the capacity the reaction foundation can bearing.
According to the purpose of the testing system, the self-reaction frame has different structure and appearance with different load capability and price. For example, the self-reaction frame of a Teaching Testing System has a rectangular appearance with load ability 500kN with total weight 3 ton, but the load frame of a Multi-purpose Servo-hydraulic controlled Structure Testing System can have a load capacity of 30,000kN and total weight of over 200 ton.
The follow figure is a typical 500kN Teaching Testing system with a self-reaction frame.
The follow figure is a 1000 ton Multi-purpose Electro-hydraulic Servo Controlled Structure Testing System with automatic testing space adjusting ability. It has a self-reaction four column frame.