Earthquake Performance Analysis of Steel Structures with A3 Plan Irregularities

In earthquake engineering, a performance-based design method is used to determine the level of the expected performance of the structures under the earthquake effect. The level of performance is related to the damage situation that could be occurred in the structure after the earthquake. In the performance-based structural design, it is predicted that more than one damage levels emerge under one certain earthquake effect. In this study, the seismic behavior of steel structures with plan irregularities in the Turkey Building Earthquake Code in the 2018 (TBEC-2018) is investigated by the nonlinear static analysis methods. The selected steel structures are located in İzmir, Turkey. The Turkey Earthquake Code in 2018 is considered for assessing seismic performance evaluation of the selected moment-resisting frame steel building. Four different A3 type irregularity was investigated. The steel building with no irregularity in its plan. was selected as the structure of the reference. The performance goals of the five different steel structures are evaluated by applying the pushover and procedures of the TBEC-2018. The steel structures were compared by obtaining pushover curves for both the X and Y directions. The results show that the effects of A3 type irregularity should be not considered in design and buildings without irregularities are safer.

Building Structure Analysis With and Without Direct Foundation Modelling using Reinforced Concrete Special Moment Resisting Frame

The modelling of placement upon the seismic resistant structure can be carried out separately or directly. Separated modelling refers to the modelling using fixed joint, while direct modelling is defined as the lower structure directly using spring on soil-foundation interaction. Both modelling have differences in the context of behaviour and reaction of structure that must be adjusted based on SNI 1726:2019 and pile needs. This research analysed the calculation of static bearing capacity of pile and manual calculation of k coefficient by Nakazawa method and a supporting program SAP2000 V14.2.5. The analysis results indicated that under the manual calculation, total pile needs on fixed joint modelling of spun pile in diameter 600 mm class B are 185 piles within pile cap modelling at every point of column, meanwhile using SAP2000 V14.2.5, it is obtained the pile needs of spring modelling are 176 piles within integral pile cap modelling. The structural behaviour and the reaction of both modelling demonstrated the values of drift control, period, mass participation, static dynamic shear force, and force output in the fixed joint modelling were less than spring modelling.

Seismic Design and Performances of Frame Structures Connected to a Strongback System and Equipped with Different Configurations of Supplemental Viscous Dampers

The paper investigates the dynamic behavior of structural systems obtained by connecting a moment-resisting frame structure with a vertical rigid truss pinned at the base, known in literature as “strongback,” and equipped with added fluid-viscous dampers. The strongback, designed in order to remain in the elastic field under strong seismic ground motion, acts as a mast by imposing to the structure a linear lateral deformed shape. By regularizing the lateral drift profile of the structure, the strongback limits undesired effects such as weak-storey mechanisms, damage concentration and residual drifts. In addition, when supplemental dampers are inserted in the structure, a considerable amount of energy can be dissipated, thus reducing the peak seismic response. The aim of the work is twofold: i) to provide analytical formulations for the preliminary design of added dampers based on the Generalized Single Degree Of Freedom (GSDOF) concept, and ii) to evaluate the increase in energy dissipation capabilities for selected dampers configurations thanks to the presence of the strongback. The formulas are developed for different configurations of added viscous dampers: dampers inserted within the frame between all or selected consecutive storeys (inter-storey placement) and dampers located at the base of the strongback to realize a rigid “dissipative tower.” The effectiveness of the dampers configurations is evaluated through dynamic time-history analyses.