Seismic response of friction damped and base-isolated frames considering serviceability limit state (original) (raw)
Related papers
Seismic Upgrading of Steel Moment-Resisting Frames by Means of Friction Devices
The Open Construction and Building Technology Journal, 2014
In recent decades, several passive energy dissipation systems have been conceived in order to minimize the damage in structural and non-structural components of either new or existing buildings. In this study, the use of friction damped tension-compression diagonal braces for seismic upgrading of a steel moment resisting frames is investigated. To this aim, nonlinear time history analyses have been carried out on a set of representative frames with and without friction damped braces. In the nonlinear time history analyses, two sets of natural accelerograms compatible with seismic hazard levels of 10% and 2% probability of exceedance in 50 years have been considered. Under these records, the structural response has been comparatively investigated in terms of the maximum inter-storey drift ratio, maximum storey acceleration, residual drift ratio and displacement demand for the friction device. The results clearly highlighted that the application of friction damped braces allows reducing the damages to the main structural elements, thus significantly improving the seismic behaviour of the frame.
Moment resisting steel frames under repeated earthquakes
In this study, a systematic investigation is carried out on the seismic behaviour of plane moment resisting steel frames (MRF) to repeated strong ground motions. Such a sequence of earthquakes results in a significant damage accumulation in a structure because any rehabilitation action between any two successive seismic motions cannot be practically materialised due to lack of time. In this work, thirtysix MRF which have been designed for seismic and vertical loads according to European codes are first subjected to five real seismic sequences which are recorded at the same station, in the same direction and in a short period of time, up to three days. Furthermore, the examined frames are also subjected to sixty artificial seismic sequences. This investigation shows that the sequences of ground motions have a significant effect on the response and, hence, on the design of MRF. Additionally, it is concluded that ductility demands, behaviour factor and seismic damage of the repeated ground motions can be satisfactorily estimated using appropriate combinations of the corresponding demands of single ground motions.
Effects of the isolation parameters on the seismic response of steel frames
Earthquakes and Structures, 2018
In this paper, an analytical study was carried out to propose an optimum base-isolated system for the design of steel structures equipped with lead rubber bearings (LRB). For this, 5 and 10-storey steel moment resisting frames (MRFs) were designed as Special Moment Frame (SMF). These two-dimensional and three-bay frames equipped with a set of isolation systems within a predefined range that minimizes the response of the base-isolated frames subjected to a series of earthquakes. In the design of LRB, two main parameters, namely, isolation period (T) and the ratio of strength to weight (Q/W) supported by isolators were considered as 2.25, 2.5, 2.75 and 3 s, 0.05, 0.10 and 0.15, respectively. The Force-deformation behavior of the isolators was modelled by the bi-linear behavior which could reflect the nonlinear characteristics of the lead-plug bearings. The base-isolated frames were modelled using a finite element program and those performances were evaluated in the light of the nonlinear time history analyses by six natural accelerograms compatible with seismic hazard levels of 2% probability of exceedance in 50 years. The performance of the isolated frames was assessed in terms of roof displacement, relative displacement, interstorey drift, absolute acceleration, base shear and hysteretic curve.
Seismic performance evaluation of steel moment resisting frames through incremental dynamic analysis
Journal of Constructional Steel …, 2010
Earthquake hazards effect significant damage to structures and cause widespread failure throughout buildings. Momentresistingframes are widely used as lateral resisting systems when sufficient ductility is to be met. Generally three types of momentresistingframes are designed in practice namely Special, Intermediate and Ordinary MomentFrames, each of which has certain level of ductility. Comparative studies on the seismicperformance of these three different types of structure are performed in this study. Analytical models of connections are employed including panel zone and beam to column joint model. Incrementaldynamicanalysis is then utilized to assess the structural dynamic behavior of the frames and to generate required data for performance based evaluations. Maximum annual probability of exceeding different limit states may reveal the superiority of a ductile structure in which a greater behavior factor is employed. Special momentresistingframes are expected to perform better once a certain level of ductility is to be met but the amount of superiority may be the subject of investigation especially from a performance based design standpoint.
Buildings
An innovative, simplified, and accurate model is proposed and developed to enable simplified yet realistic time history analysis of multi-storey buildings with moment resisting connections using friction energy dissipaters in the commonly used structural analysis and design program, SAP2000. The analyses are rapid to undertake, thereby enabling detailed study of the influence of many building system effects on the overall response. This paper presents the outcome of dynamic analysis of a complete 13-storey moment resisting steel building with Sliding Hinge Joints as the beam-column connections, considering the influential self-centring factors such as MRF and gravity columns continuity as well as column base and diaphragm flexibilities. The building is one of the Te-Puni towers, which are structural steel apartment buildings with steel-concrete composite floors, designed according to the low damage design philosophy, built in Wellington, New Zealand in 2008 and which have already be...
Seismic damage avoidance design of moment resisting frames with innovative resilient connection
2020
Moment-resisting frames are one of the efficient lateral-load resisting systems in terms of providing architectural freedom in design and imposing smaller forces on foundations. Recent major earthquakes have resulted in significant plastic deformations in the beam-column connections causing irrecoverable damage in such structures. As a result, engineers have focused on developing new systems which not only provide the life-safety of the residents, but also minimise the damage such that the building could be reoccupied quickly after severe events with minimal business interruption and repair costs. In this paper, a self-centring damage avoidance concept using the innovative Resilient Slip Friction Joint (RSFJ) is developed for steel Moment Resisting Frames (MRFs). The RSFJ provides the selfcentring behaviour as well as energy dissipation in one compact component requiring no post-event maintenance. In this concept, the beam is connected to the column using a pin mechanism at the top,...
International Advanced Researches & Engineering Congress, 2017
Many researchers have already acknowledged the base isolation system as the most feasible and economical method for civil engineering structures exposed to the seismic excitation. The Friction Pendulum Systems (FPS) have steel concave surface connected with articulated friction slider and that utilized the concept of pendulum for lengthening the period of the superstructure so as to dissipate the seismic energy. The present study investigates on various design approaches for the evaluation of the seismic response of steel frames equipped with FPS. The response of isolated frames is simply adjusted by several parameters such as the friction coefficient (, the radius of curvature (R) and the axial load and so 2D, three bay 3 and 7-storey steel moment resisting frames (SMRF) are designated as isolated frames in order to examine the effect of variation of the R and the friction coefficient on the seismic response of the isolated frames. The R and the friction coefficient are predefined as 1, 1.55, 2.25 and 0.025, 0.05, 0.1, respectively. The seismic response of the modelled isolation systems has been evaluated through nonlinear time history analyses, a set of ground motions using SAP2000 software. The local and global deformations are employed to compare the seismic performance of different isolation frames through nonlinear analysis. The results showed that the isolated frames having greatest radius of curvature with lowest friction coefficient exhibited better seismic performance than other models in terms of the local and global deformations.
Seismic performance of dual-steel moment resisting frames
Journal of Constructional Steel Research, 2014
Traditionally, lateral stiffness and strength of the gravity frames in steel buildings are neglected in structural analysis. During the past earthquakes, such as Northridge, USA, 1994 and Kobe, Japan, 1995, unexpected failures were detected at beam-tocolumn connections of steel moment resisting frames (MRFs). In the aftermath of these earthquakes, extensive research has been carried out to reveal the causes of these failures. Based on the detailed observations, it is likely that the reserve capacity provided by the gravity frames prevented the highly damaged steel buildings from collapsing, since majority of the momentresisting connections failed prematurely during the Northridge earthquake (1994). Even though the influence of gravity frames (GFs) on structural behavior can be substantial, little attention is paid to evaluate its impact on structural response. With this paper, the contribution of interior GFs in seismic performance of special moment resisting steel frames (SMRFs) is evaluated. For this purpose, 4-and 9-story SMRFs were designed in accordance with the requirements of Draft Turkish Seismic Code (2016). The frames are, then, subjected to incremental dynamic analysis. To evaluate the contribution of the interior GFs on the overall seismic performance of structural system, inelastic behavior of shear tab (simple) connections at beam-to-gravityonly columns were idealized as semi-rigid joints. A general purpose structural analysis software, ETABS, is utilized for the analyses. The results of the study are presented in terms of story drifts, base shear vs. roof displacement.
Using bracing systems to improve the seismic performance of moment resisting frame
JES. Journal of engineering sciences, 2022
Bracing systems [BS] have been widely adopted as the primary lateral load resisting system in medium and high-rise buildings due to their inherent substantial lateral stiffness and load resistance, and it is considered the most effective method for fusing existing RC structures. Therefore, the seismic response of steel braced frames [SBF] with bracing members connected to the columns had been explored for a moment-resisting frame [MRF]. And different configurations of BS had been investigated to study their effects on lateral load resistance and get the optimized bracing configurations. Moreover, the study doesn't take into consideration only the BS over the height of the building, but it also reduces the length of the bracing element by adding many bracing panels over the height of stories which can lead to an increase in the resistance of seismic loading. The bracing panels can be an effective technique in dealing with the architects' constraints. Therefore, smaller brace components can be chosen for studying to avoid the architect's constraints and create different configurations while still meeting code criteria for brace strength and overall slenderness. The earthquake behavior of the retrofitted structure was analyzed by distributing the SB of various types (X, V inverted) over the height of the RC frame. The results demonstrate that the smaller brace components for X & V inverted bracing can contribute to reducing the lateral displacement and maximum story drift.