Effect of Tributary Area of Columns on the Progressive Collapse of Reinforced Concrete Structures

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Effect of Tributary Area of Columns on the Progressive Collapse of Reinforced Concrete Structures

ارائه دهنده: Provider: Fatemeh Vakili Zahir

اساتید راهنما: Supervisors: Freydoon Rezaie (Ph.D)

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: دکتر محمود نیلی - دکتر مصطفی مقدسی

زمان و تاریخ ارائه: Time and date of presentation: 29/11/98

مکان ارائه: Place of presentation: آمفی تئاتر

چکیده: Abstract: The extension of the initial localized chain failure from one member to another which eventually causes the entire structure to collapse or disproportionately destroy a large part of it, is called progressive collapse. The purpose of this study is to evaluate the effect of tributary area of columns on the progressive collapse due to sudden removal of column in regular reinforced concrete structures with bending frame system in both directions. Progressive collapse in two buildings of 5 and 6 stories with different span lengths has been investigated by nonlinear dynamic analysis based on the alternative path method based on GSA code in Opensees software. In the 5-storey structure, the spans are the same length and the three modes of corner, middle and outer column removal have been investigated. But the 6-storey structure has different span lengths and 8 column removal modes are considered in different plan positions with different tributary areas. The results of the analysis including the rotation of beams attached to the removed member, the vertical displacement of the point above the removed member column, the axial force changes in the adjacent columns of the removed column, the shear force changes in the adjacent columns of the removed column, and the vertical velocity of the point above the removed column . In the 5-storey structure, the largest value of λ index is related to the removal of the corner column. In the first floor of the 6-storey structure, the largest value of λ index is related to the removal of the middle column, which has the largest area of the column tributary . The increase in λ index indicates that the structure loses more gravity hardness when removing the column. The column tributary area and column's positioning have a significant impact on the vertical displacement of the removed column. Also, the smaller the column cross section, the greater the vertical displacement. moreover, removing the column in the first floor is more critical than removing the third floor column. The largest value of the β index or the column sensitivity index is related to the removal of the external column. In other words, the most critical load distribution in the adjacent columns of the removed column occurs in the external column deletion mode. The smaller the tributary area of the columns adjacent to the removed columns, the greater the load distribution in the adjacent columns removed. In the five-storey model, the most critical load distribution mode is the removal of the corner column. Key Words: Progressive collapse, Tributary area of columns, Nonlinear dynamic analysis, Sudden removal

فایل: ّFile: Download فایل