Midspan joints

The company BASF (Germany) has launched the production of poly-ethersulfone labeled Ultrason E [169] representing amorphous thermoplastic product of polycondensation it can be characterized by improved chemical stability and fire-resistance. The pressed articles made of it differ in solidity and rigidity at temperature 200 °C. It is assumed to be expedient to use this material when producing articles intended for exposure to increased loadings when the sizes of the article must not alter at temperatures from -100 °C till 150 °C. These items are, for instance in electrotechnique, coils formers, printing and integrated circuits, midspan joints and films for condensers. 

For a simple rectangular pinned base frame made of shear deformable members joined together by semi-rigid connections with a linear moment-rotation characteristic, it is possible to develop simple closed-form expressions for the deformations at points of particular interest, e.g. midspan deflection (wj and joint rotations. Such expressions have been derived assuming that the beam (span=b) and columns (height=a) are made of the same sections. For example, the expression for the mid-span deflection of the beam when the frame is loaded in a flexural mode is as follows ... 

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