scholarly journals Fragility Curves and Probabilistic Seismic Demand Models on the Seismic Assessment of RC Frames Subjected to Structural Pounding

2021 ◽  
Vol 11 (17) ◽  
pp. 8253
Author(s):  
Maria G. Flenga ◽  
Maria J. Favvata
Keyword(s):  
Fragility Curves ◽  
Seismic Demand ◽  
Rc Structures ◽  
Structural Pounding ◽  
Rc Frames ◽  
Rc Structure ◽  
Demand Models ◽  
Probabilistic Seismic Demand ◽  
Displacement Based ◽  
The Impact

This study aims to evaluate five different methodologies reported in the literature for developing fragility curves to assess the seismic performance of RC structures subjected to structural pounding. In this context, displacement-based and curvature-based fragility curves are developed. The use of probabilistic seismic demand models (PSDMs) on the fragility assessment of the pounding risk is further estimated. Linear and bilinear PSDMs are developed, while the validity of the assumptions commonly used to produce a PSDM is examined. Finally, the influence of the PSDMs’ assumptions on the derivation of fragilities for the structural pounding effect is identified. The examined pounding cases involve the interaction between adjacent RC structures that have equal story heights (floor-to-floor interaction). Results indicate that the fragility assessment of the RC structure that suffers the pounding effect is not affected by the examined methodologies when the performance level that controls the seismic behavior is exceeded at low levels of IM. Thus, the more vulnerable the structure is due to the pounding effect, the more likely that disparities among the fragility curves of the examined methods are eliminated. The use of a linear PSDM fails to properly describe the local inelastic demands of the structural RC member that suffers the impact effect. The PSDM’s assumptions are not always satisfied for the examined engineering demand parameters of this study, and thus may induce errors when fragility curves are developed. Nevertheless, errors induced due to the power law model and the homoscedasticity assumptions of the PSDM can be reduced by using the bilinear regression model.

scholarly journals Effect of Aftershocks on Seismic Fragilities of Single-Story Masonry Structures

2021 ◽  
Vol 9 ◽  
Author(s):  
Hao Zhang ◽  
Tong Sun ◽  
Shi-Wei Hou ◽  
Qing-Meng Gao ◽  
Xi Li
Keyword(s):  
Seismic Response ◽  
Fragility Curves ◽  
Limit State ◽  
Unreinforced Masonry ◽  
Aftershock Sequence ◽  
Seismic Demand ◽  
Masonry Structures ◽  
Confined Masonry ◽  
Demand Models ◽  
Probabilistic Seismic Demand

The effect of aftershocks on the fragility of single-story masonry structures is investigated using probabilistic seismic demand analysis Finite element models of an unreinforced masonry (URM) structure and a confined masonry (CM) structure are established and their seismic response characteristics when subjected to mainshock, aftershock, and the mainshock-aftershock sequence are then comparatively investigated. The effects of aftershocks and the use of confining members on the seismic response are studied. Probabilistic seismic demand models of the structures are built, and fragility curves under various conditions are derived to investigate the effect of aftershocks on structural fragility. The maximum roof displacement and maximum inter-story drift ratio are lower in the confined masonry model than in the unreinforced masonry model; additionally, the probability of exceedance (PE) values of each damage limit state reduced, and those of the mainshock-damaged models subjected to aftershock significantly increase compared to those directly subjected to a same-intensity aftershock. The probability of severe damage or collapse compared with the mainshock-damaged CM model is greater than when each is subjected to a same intensity aftershock. The use of confining members benefits aftershock resistance and reduces the failure probability of the mainshock-damaged structure. The PE values significantly increase with the aftershock scaling factor δ. Therefore, the effect of aftershocks should be considered in the seismic design and analysis of masonry structures.

scholarly journals Fragility Curves for RC Structure under Blast Load Considering the Influence of Seismic Demand

2020 ◽  
Vol 10 (2) ◽  
pp. 445
Author(s):  
Flavio Stochino ◽  
Alessandro Attoli ◽  
Giovanna Concu
Keyword(s):  
Reinforced Concrete ◽  
Simulation Analysis ◽  
Fragility Curves ◽  
Probabilistic Approach ◽  
Blast Load ◽  
Seismic Demand ◽  
Technical Standards ◽  
Rc Structure ◽  
Probabilistic Study ◽  
Explosion Load

The complex characteristics of explosion load as well as its increasingly high frequency in the civil environment highlight the need to develop models representing the behavior of structures under blast load. This work presents a probabilistic study of the performance of framed reinforced concrete buildings designed according to the current Italian NTC18 and European EC8 technical standards. First, a simplified single degree of freedom model representing the structural system under blast load has been developed. Then, a probabilistic approach based on Monte Carlo simulation analysis highlighted the influence of seismic demand on the behavior of Reinforced Concrete RC buildings subjected to blast load.

Tension Stiffening Analysis for Cyclically Loaded RC Beams

2014 ◽  
Vol 567 ◽  
pp. 517-521
Author(s):  
Ahmad Azim Bin Shukri ◽  
Mohd Zamin Jumaat
Keyword(s):  
Rc Beams ◽  
Interaction Theory ◽  
Tension Stiffening ◽  
Rc Structures ◽  
Friction Theory ◽  
Rc Structure ◽  
Partial Interaction ◽  
Interface Displacement ◽  
Displacement Based ◽  
The Moment

Ductility is an important aspect of cyclically loaded reinforced concrete (RC) structures. One of the method that can be used to measure the ductility of an RC structure is the moment-curvature approach. However, due to it being a strain-based approach it cannot be used to directly simulate behaviour associated with interface displacement that occur when an RC member is cracked. This leads to dependency on empirical values, which imposes limitations on how the moment-curvature approach can be used. In recent years a new displacement based method for measuring ductility has been developed, and can simulate the interface displacement behaviours through the use of partial-interaction theory and shear friction theory. This paper aims to extend the general tension stiffening analysis of the displacement-based approach to allow for cyclic loading. The tension-stiffening analysis was then validated against experimental results and the results were found to agree fairly.

scholarly journals Fragility Analyses of Bridge Structures Using the Logarithmic Piecewise Function-Based Probabilistic Seismic Demand Model

2021 ◽  
Vol 13 (14) ◽  
pp. 7814
Author(s):  
Yinghao Zhao ◽  
Hesong Hu ◽  
Lunhua Bai ◽  
Mengxiong Tang ◽  
Hang Chen ◽  
...  
Keyword(s):  
Fragility Curves ◽  
Statistical Significance ◽  
Seismic Intensity ◽  
Fragility Analysis ◽  
Seismic Demand ◽  
Demand Model ◽  
Intensity Measure ◽  
System Fragility ◽  
Probabilistic Seismic Demand ◽  
Seismic Demand Model

Seismic fragility analysis is an efficient method to evaluate the structural failure probability during earthquake events. Among the existing fragility analysis methods, the probabilistic seismic demand model (PSDM) and the joint probabilistic seismic demand model (JPSDM) are generally used to compute the component and system fragility, respectively. However, the statistical significance behind the parameters related to the current PSDM and JPSDM are not comparable. Aside from that, when calculating the system fragility, the Monte Carlo sampling (MCS) method is time-consuming. To solve the two flaws, in this paper, the logarithm piecewise functions were used to generate the PSDM and the JPSDM, and the MCS was replaced by the univariate conditioning approximation (UCA) method. The concepts and application procedures of the proposed fragility analysis methods were elaborated first. Then, the UCA method was illustrated in detail. Finally, fragility curves of a steel arch truss case study bridge were generated by the proposed method. The research results indicate the following: (1) the proposed methods unify the data sources and statistical significance of the parameters used in the PSDM and the JPSDM; (2) the logarithmic piecewise function-based PSDM sensitively reflects the changing trend of the component’s demand with the fluctuation of the seismic intensity measure; (3) under transverse seismic waves, major injuries happen on the side bearings of the bridge, while slight damage may occur on each pier, and as the seismic intensity measure increases, the side bearings are more likely to be damaged; (4) for the severe damage and the absolute damage of the studied bridge, the system fragility curves are closer to the upper failure bounds; and (5) compared with the MSC method, the accuracy of the UCA method can be guaranteed with less calculation time.

scholarly journals Novel Global Interconnect structure with improved Elmore Delay Estimation for Low-Power Applications

2021 ◽  
Author(s):  
Himani Bhardwaj ◽  
Shruti Jain ◽  
Harsh Sohal
Keyword(s):  
Power Consumption ◽  
Vlsi Circuits ◽  
Delay Estimation ◽  
Rc Structures ◽  
Vlsi Interconnects ◽  
Rc Structure ◽  
Distributed Circuits ◽  
Scale Down ◽  
Relationship Of ◽  
The Impact

Abstract With advancements in technology, size and speed have been the important facet in VLSI interconnects. Interconnects are known as the basic building block that provide a connection between two or more blocks and have scaling problems that an IC designer faces while designing. As scaling increases, the impact of interconnect in the VLSI circuits became even more important. It controls all the important electrical characteristics on the chip. With scale-down technology, interconnects not only become closer with each other but their dimensions also change which can directly impact the circuit parameters. Certain RC structures have already been defined to control these parameters but in this paper, authors have proposed a new interconnect structure with improved Elmore delay estimation to reduce delay and power consumption in lumped and distributed interconnect circuits using Pulse and Ramp inputs. Further, the proposed model is estimated and verified theoretically. The linear relationship of power consumption and delay for the RC structure has been observed. The proposed structure with improved Elmore delay estimation shows improvement in delay by 64.25% in lumped circuits and 68.75% in distributed circuits in comparison to existing Elmore delay calculations which help in increasing the overall speed of the interconnect circuit.

scholarly journals Effect of Aftershock Characteristics on the Fragility Curve of Post-Mainshock RC Frames

2021 ◽  
Author(s):  
Ali Massumi ◽  
Kabir Sadeghi ◽  
Omid Ghojoghi
Keyword(s):  
Fragility Curves ◽  
Significant Duration ◽  
Rc Frames ◽  
Collapse Probability ◽  
Site Characteristics ◽  
Wide Range ◽  
Seismic Records ◽  
Earthquake Sequences ◽  
The Impact ◽  
Selection Of

Abstract Buildings constructed in seismic zones are not only damaged by mainshocks but may also be damaged by the impact of aftershocks and cause them to collapse. Therefore, studying the behavior of the damaged structures due to the mainshock and aftershock helps in post-mainshock decision making and also in the selection of suitable aftershock records for seismic assessing of the structure under earthquake sequences. This paper presents the effects of aftershock ground motion on the collapse capacity of post-mainshock buildings. The mean period (Tm), predominant velocity period (Tg), frequency bandwidth (Ω), the 5%-95% significant duration (Ds) and seismic records of different sites were selected to evaluate the effect of its characteristics on the collapse capacity of buildings. The intensity of the ground motions was determined by the first-mode spectral acceleration with 5% damping. Collapse capacities of two non-ductile reinforced concrete (RC) frames with 3 and 6 stories were evaluated using a set of 62 aftershock records with a wide range of characteristics. Box plot collapse diagrams and fragility curves have been developed by applying the incremental dynamic analysis (IDA). The results show that in the frequency content with a longer period, the probability of its collapse is higher. In addition, the high significant duration of aftershocks increases the collapse probability of structures. Also, the evaluation of the site characteristics shows differences in collapse capacities of the same frames in varying sites. Therefore, the effect of aftershock characteristics on the capacity of the structures is significant and it is necessary to carefully determine the seismic sequences’ recordings for the evaluation of the seismic behavior of the structures.

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