To achieve the minimum weight design of large-span statically determinate trusses under displacement constraint, a method called the coefficient distribution method was proposed. The calculation formula of the displacement for statically determinate trusses was provided at first. Then the critical condition of minimum weight design satisfying the allowable displacement was deduced using Cauchy Inequality. At last, the distribution coefficient of material consumption, which was used to determine

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... the proportional relationship of weight of each member in a truss, was defined. An example was analyzed using the coefficient distribution method. Study results show that the coefficient distribution method is correct, reliable and effective. Keywords-the allowable displacement; the minimum weight design; the coefficient distribution method; large-span determinate truss