Summary: A feedback control problem for a beam under constant and harmonic moving loads is formulated and solved. The objective of the control is to satisfy a barrier condition which places an upper bound on the deflection. The feedback is taken proportional to the transverse displacement of the beam. The location and time of the maximum deflection depend on the feedback parameter which is determined from the solution of a minimax problem. Numerical results are given for various problem parameters and the efficiency of the proposed control is investigated. A measure of the amount of force spent in the control process is also determined to assess the effect of displacement constraint on the force expenditure.