Seismic damage characteristics of steel structures
Second, the destruction of components
This form of damage is very common in frame-supported steel structures building. The supporting rod can be regarded as a simply supported axial force member at both ends. Under the action of wind load and frequent earthquakes, the supporting rod can be kept in an elastic working state. Generally, it will not lose the overall stability as long as the design is proper. Under the action of rare earthquakes, the central support members will be subject to huge reciprocating tension and compression, generally the overall instability will occur and enter the plastic yield state, dissipating energy. However, with the increase of the number of tension-compression cycles, the bearing capacity will degenerate. When the support loses its stability under the action of pressure, it will become the bent rod, the load force will drop rapidly and the plastic hinge will be formed in the central part of the rod. Because of the residual plastic bending deformation, the tensile stiffness is very small. Only when the plastic hinge is formed in the opposite direction, the tensile stiffness of the support gradually recovers until the full cross-section is supported by the slenderness ratio of the yield and elongation. The overall loss The stability of the bearing capacity than the slender than the smaller is much more serious.
Third, the collapse of the structure destroyed
In the 1985 Mexican earthquake, one of the three 22-story steel structure building towers of the PinoSuarez complex in Mexico City collapsed and the remaining two also suffered serious damage, of which one was nearly collapsed. The analysis of the structure of the three towers is the analysis of the support structure of the frame. One of the main reasons for the collapse and serious damage to the tower is that the vertical and horizontal vertical supports are offset and set so that the stiffness center and the mass center of gravity are far apart. During the earthquake Resulting in a larger torsional effect, resulting in a steel column force greater than its bearing capacity, triggering three identical towers severely damaged or collapsed. Thus, the symmetrical steel structural symmetry of the system will be very favorable for the earthquake.