Elastic stability of a pony truss

Alexander Hrennikoff
The author of this paper endeavor to find an expression for the value of the load, which causes collapse of certain type of bridge without the top lateral bracing. A qualitative study of the question reveals, that the resist lag action of the web members is greatly affected by the magnitudes of their axel stresses; and this conclusion leads to the necessity of determination of web resistances in terms of loading the energy method consisting in comparison of the elastic energy of structure with
more » ... of structure with the work done by the loading during buckling, is used as the method of attack of the main problem. After evaluation of various terms in the energy equation, expressions for the critical values of different types of loadings are found. An observation of the fact, that the shape of buckling curve is affected by the loading only very slightly leads to the idea of reciprocal influence line of critical loading, allowing an easy treatment of the questions involving movable load. The application of the formulas developed is demonstrated on an example, and the paper is concluded with some final remarks, on the method and its assumptions.
doi:10.14288/1.0050911 fatcat:vdz2d6ibu5dkpn4ujwvo2x33ki