Comparative Evaluation of Behavior Factor of SMRF Structures for Near and Far Fault Ground Motions

In common design codes, earthquake loads are reduced by a coefficient (behavior factor) which depends on nonlinear seismic performance of structure during earthquake event. Nonlinear performance of structures depends on structural properties and ground motion characteristics. There are different methods for estimation of seismic response parameters such as behavior factor. One of the approaches is using incremental dynamic analysis. This paper gives estimations of behavior factor for special moment-resisting steel frames under near and far fault records using incremental dynamic analyses. Three moment resisting frames with, 3, 6, and 10 stories, are considered for evaluations employing two performance levels (Life Safety and Collapse Prevention). One aspect of difference among earthquake records is existence of velocity pulse in their time-history. This issue is investigated through evaluation of R factor for three frames. It is shown that behavior factor for near fault records is averagely 23% less than far fault records

E-discovery viewed as integrated human-computer sensemaking: the challenge of 'Frames'

In addressing the question of the design on technologies for e-discovery it is essential to recognise that such work takes place through a system in which both people and technology interact as a complex whole. Technology can promote discovery and insight and support human sensemaking, but the question hangs on the extent to which it naturally extends the way that legal practitioners think and work. We describe research at UCL which uses this as a starting point for empirical studies to inform the design of supporting technologies. We report aspects of an interview field study with lawyers who worked on a large regulatory investigation. Using data from this study we describe document review and analysis in terms of a sequence of transitions between different kinds of representation. We then focus on one particular transition: the creation of chronology records from documents. We develop the idea that investigators make sense of evidence by the application of conceptual ‘frames’ (Klein et al’s, 2006), but whilst the investigator ‘sees’ the situation in terms of these frames, the system ‘sees’ the situation in terms of documents, textual tokens and metadata. We conclude that design leverage can be obtained through the development of technologies that aggregate content around investigators’ frames. We outline further research to explore this further

Assessment Of Building Fragility Curve Due To Earthquake Excitation

In this study, the main objective is to develop fragility curve of regular and irregular moment-resisting frame based on different types of structural material, height, and ground motion records. 6 sets of concrete and steel frames were used in this study and varied in terms of heights which are 3-, 6- and 9-storey for regular and irregular frame. Each structure frames was designed based on Eurocode 2 and 3 with the aid Eurocode 8 for earthquake loading. The SAP2000 was used as the main tool to carry out the analysis. A pushover analysis (POA) was performed to get the performance of the structure due to static load. Triangular load was used to produce base shear-drift relationship. Then, an incremental dynamic analysis (IDA) was carried out with 3 ground motion records for each set near and far field. In addition, the Ranau earthquake also considered in this study for two types of case; single and repeated earthquake. While to develop the fragility curve, the result from IDA will be used as the main parameters. The IDA curves were compared with five level of performance level from Xue et al. (2008) study which are operation phase (OP), immediate occupancy (IO), damage control (DC), life safety (LS), and collapse prevention (CP). On the basis of the result of this thesis, it can be concluded that from POA result showed regular frames demonstrate a higher demand compared to irregular frames for concrete and steel frames. From the IDA results, it was proven that regular frames perform better for both materials under near and far field records. Based on the fragility curves developed for the near and far field records, irregular frames showed a higher probability of reaching or exceeding the performance level for concrete frame. On the other hand, regular steel frames showed a higher probability of reaching and exceeding the performance level

Refining Historical earthquake Data Through Modeling and Scale Model Tests

This study was performed for the reevaluation of historical earthquake records which occurred in Korea through tests and numerical analyses. For the scale model tests, static and cyclic lateral load tests on wooden frames that constitute a Korean ancient commoner’s house were conducted. Full-scale models of two types of frames were used for testing. Two 1:4 scale models were tested for rock and soil foundation conditions. Scaled real earthquake time histories were inputted for the tests. The peak ground acceleration (PGA) at the collapse of the house at the soil site was 0.25g, whereas PGA for moderate damage at the rock site was 0.6g. The intensity of major historical earthquake records related with house collapses was reevaluated based on the results of these scale mode1 tests. The magnitudes of historical earthquake records related with house collapses were estimated considering the magnitude, epicentral distance, soil condition and aging of the house. Eighteen artificial time histories for magnitudes 6-8, epicentral distances 5 km - 350 km and hard and soft soil condition were generated. The aging effects of the house was modeled as the lateral loading capacity of wooden frames represented by hysteretic stiffness decreased linearly with time

Seismic performance of ductile corrosion-free reinforced concrete frames

Corrosion of steel bars is the main cause of the deterioration of reinforced concrete (RC) structures. To avoid this problem, steel rebars can be replaced with glass-fiber-reinforced-polymer (GFRP). However, the brittle behaviour of GFRP RC elements has limited their use in many applications. The use of shape memory alloy (SMA) and/or stainless steel (SS) rebars can solve this problem, because of their ductile behaviour and corrosion resistance. However, their high price is a major obstacle. To address issues of ductility, corrosion, and cost, this paper examines the hybrid use of GFRP, SS, and SMA in RC frames. The use of SMA provides an additional advantage as it reduces seismic residual deformations. Three frames were designed. A steel RC frame, SS-GFRP RC frame, and SMA-SS-GFRP RC frame. The design criteria for the two GFRP RC frames followed previous research by the authors, which aimed at having approximately equal lateral resistance, stiffness, and ductility for GFRP and steel RC frames. The three frames were then analyzed using twenty seismic records. Their seismic performance confirmed the success of the adopted design methodology in achieving corrosion-free frames that provide adequate seismic performance

Single-shot ultrafast imaging attaining 70 trillion frames per second

Real-time imaging of countless femtosecond dynamics requires extreme speeds orders of magnitude beyond the limits of electronic sensors. Existing femtosecond imaging modalities either require event repetition or provide single-shot acquisition with no more than 10¹³ frames per second (fps) and 3 × 10² frames. Here, we report compressed ultrafast spectral photography (CUSP), which attains several new records in single-shot multi-dimensional imaging speeds. In active mode, CUSP achieves both 7 × 10¹³ fps and 10³ frames simultaneously by synergizing spectral encoding, pulse splitting, temporal shearing, and compressed sensing—enabling unprecedented quantitative imaging of rapid nonlinear light-matter interaction. In passive mode, CUSP provides four-dimensional (4D) spectral imaging at 0.5 × 10¹² fps, allowing the first single-shot spectrally resolved fluorescence lifetime imaging microscopy (SR-FLIM). As a real-time multi-dimensional imaging technology with the highest speeds and most frames, CUSP is envisioned to play instrumental roles in numerous pivotal scientific studies without the need for event repetition

A simplified model for seismic response prediction of concentrically braced frames

This paper proposes a simplified analytical model for seismic response prediction of concentrically braced frames. In the proposed approach, a multistory frame model is reduced to an equivalent shear-building one by performing a static pushover analysis. The conventional shear-building model has been improved by introducing supplementary springs to account for flexural displacements in addition to shear displacements. The adequacy of the modified model has been verified by conducting non-linear dynamic analysis on 5, 10 and 15 story concentrically braced frames subjected to 15 synthetic earthquake records representing a design spectrum. It is shown that the proposed improved shear-building models provide a better estimate of the non-linear dynamic response of the original framed structures, as compared to the conventional models. While simplifying the analysis of concentrically braced frames to a large extent, and thus reducing the computational efforts significantly, the proposed method is accurate enough for practical applications in performance assessment and earthquake-resistant design