This paper describes the development of robotic manipulator's shock isolation control algorithm which provides stable and efficient gripping of a pendulum-motion object wire-suspended by a crane. This control algorithm requires dynamic modeling of the hanging object to estimate the amount of the shock. The dynamic model mimics the steel beam suspended by the crane and the robot to grip the beam in 3-dimesional space. Under limited impact, the manipulator grips the object with pre-acting control that can increase the duration of the impact time. In this paper, assuming that location information is provided by a vision system, dynamic simulations are presented, which is very similar to the actual steel beam assembly in building construction environment. The goal of this paper is to evaluate how force, vibration, and stabilization time exerted on the entire robot arm system change before and after applying 'pre-acting control algorithm' through the simulations. Also, based on the simulation results, it was concluded that this pre-acting control algorithm can be efficiently applied to real construction sites as well as other industrial sites in the future.