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Direct Displacement-Based Seismic Design of Eccentrically Braced Steel Frames Gerard J. O’Reilly & Timothy J. Sullivan Abstract A series of eccentrically braced frames (EBF) are designed and subjected to nonlinear analyses to highlight ambiguities and differences in current seismic design provisions for EBF structures. This provides motivation to implement better guidance for the checking of local displacement demand considerations and move towards a displacement-based design approach. A recently proposed direct displacement-based design (DDBD) procedure for EBFs is then described and further developed in this paper through the calibration of a spectral displacement reduction factors that relate the displacement of an inelastically responding structure to that of the equivalent linear representation used in the DDBD of EBFs. Such an expression is calibrated as part of this study using an experimentally validated numerical model also proposed here for the EBF links such that the actual hysteretic behaviour of the links is well represented. The DDBD guidelines are applied to EBF systems from 1 to 15 storeys in height and their performance is verified via nonlinear dynamic analyses using two different sets of design spectrum compatible ground motions. The results of the study indicate the robustness of the proposed DDBD method in limiting the interstorey drifts to design limits for a variety of EBF systems with short links, thus demonstrating that the proposed DDBD method is an effective tool for seismic design of EBFs. TandF_1485618928.rar

Strengthening Demand of Columns in A RCC Structure Due To Construction of An Additional Storey Mohd Irfan, D r . Abhay Sharma, Dr. Vivek G arg PG Scholar, Associate Professor Assistant Profe ssor Civil Engineering Department Civil Engineering Department Civil Engineering Department NIT Bhopal, Madhya Pradesh, India. NIT Bhopal, Madhya Pradesh, India NIT Bhopal, Madhya Pradesh, India .Abstract - Generally the people construct the structure to fulfill their current needs but with the passage of time they realize that their demands have increased and there is a need for the addition/alteration of the current structure. This demand can be fulfilled by constructing a new storey. However, provision for additional load due to the new construction over existing structure was not made in the structural design of the old structure. Therefore, the construction of new storey requires the strengthening of the old structure. The present study investigates the structural behaviour of an RC frame under the additional load in the form of a new storey. The analysis of existing structure (two storey) and proposed structure (one additional storey constructed over existing two storey structure) is performed by using structural analysis software i.e. STAAD Pro. The analysis results of existing and proposed structure are compared to evaluate the increase in structural forces due to the construction of a new storey. The results indicates that the significant increase is found in the axial force and bending moment in columns. The weak and deficient columns are identified and strengthened for the additional loads and additional moments. The strengthening of columns is done by jacketing of the columns using four steel angles at corners, confined with the help of batten plates placed at equal spacing along the length of the column. Keywords- Concrete; Steel; Jacketing; Strengthening. منبع : کانال تلگرام بهسازی و مقاوم سازی سازه ها [Hidden Content] V3I8_IJERTV3IS080489.pdf