This paper presents a finite element seismic response simulation of a typical tower crane frame using SAP2000. Threedimensional beam elements and bar elements are employed for vertical and horizontal frames as well as the tie rods, respectively, to build up the numerical model. Then numerical example is considered and two kinds of earthquake ground accelerations are tested, i.e., 1940 NS component of the El Centro and 1995 Kobe accelerations. The dynamic responses of displacement, velocity and accelerations of a typical node of the tower crane frame are illustrated and discussed. The numerical simulation results show that the maximal displacements might be large to over 1 meter and the associated maximal velocity and acceleration can be greater than 4 m/s and 40 m/s2, respectively at the highest position of tower crane.
Tower cranes are widely employed in civil engineering for construction of high-rise buildings. During the period of construction it becomes an additional structure aside of the constructed building and thus its structural stability and safety is of the same importance with the major target building. In the past many preceding preliminary studies on the static, stability and dynamic behaviors of the tower crane for high-rise buildings have been conducted [1-10]. Some disasters related to the tower cranes occurred in the past in Taiwan and other countries are due to different causes: earthquake shaking-down, fracture of members, flexural failure, etc. . The disasters caused from the tower cranes include the destruction of the construction apparatus, people hit by the heavy falling-down components, induced failure of subordinate structures, etc.
The special features of tower crane structures are their relatively light weight and flexible as compared with the major target building. When subjected to wind loading and earthquake excitation, giant displacements and internal stresses of the structural members might be induced and lead to sudden failure and/or long-term fatigue. From the points of view on structural mechanics, tower crane frame is a integrated three-dimensional truss or frame structure made with a lot of bar elements, to form an integrated structures comprised with a major vertical supporting column, a horizontal loading arm and some tensile tendons. However, analytical structural analysis of tower-type is difficult due to its complicated and three-dimensional features and many trials are based on the matrix methods of structural analysis and finite element methods.
This paper presents numerical modeling and structural dynamic analysis of a typical tower crane employed in construction engineering. SAP2000 software was employed and finite element method is adopted. A typical numerical example was considered, totally 516 three-dimensional beam elements with 207 nodes are employed for the vertical and horizontal frame parts and bar elements are used for tensile tendons, respectively. Natural frequencies and vibration modes were discussed and then the seismic responses due to 1940 NS component of El Centro and 1995 Kobe ground accelerations are discussed in detail.