الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 118 |  |  |
| | | from | 118 | | |
Abstract
The aim of the present work is to investigate the effects of irregularities in the distribution of building columns on the behavior of these building under the effect of lateral load or ground motion, For this purpose a solution technique based on finite element method is used, and three dimensional linear analyses for static and dynamic analysis are carried out using standard program ( ST AAD III ).
In the analysis, Three different patterns of columns distribution are adopted. In the first pattern, the columns are put in rows parallel to each other in the two directions to give symmetric structure. In the second pattern, the columns are put in irregular distributions but the symmetry of the structure is kept, while the third pattern represents the general case ~f irregularity, Each case of columns distribution pattern is analyzed for two different cases of loadings: static lateral load, and ground acceleration loadings. The sum of columns stiffnesses at each story and the beams stiffness in the two direction at each level are kept constant in the three patterns. Effect of cracks is considered by modifying the gross moment of inertia of the beam and column cross-sections. Several buildings of different floor systems (beams and flat plate) are solved for the two cases of loading considered.
Irregular distribution of columns, even if they are symmetric, increases the flexibility of building and hence the straining actions in columns and beams. The flexibility of the building increases for unsymmetric cases and increases more as the eccentricity of center of rigidity ;ncreases. The effect of irregularities on frequency range of building (period of vibration) and its damping characteristic can be ignored although, the effect of this irregularities on response amplitude and hence the internal forces should be considered.