scholarly journals Seismic Vulnerability Analysis of Rural Modified Raw-Soil Structures

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Shiwei Hou ◽  
Hao Zhang ◽  
Yuzhe Zhang ◽  
Xin Chen ◽  
Suyun Meng
Keyword(s):  
Seismic Vulnerability ◽  
Waste Utilization ◽  
Coal Gangue ◽  
Calcined Clay ◽  
Response Characteristics ◽  
Soil Model ◽  
Structural Resistance ◽  
Soil Structures ◽  
Probabilistic Seismic Demand ◽  
Modified Soil

Based on the concept of environmental protection of solid waste utilization, material testing is conducted to achieve native improvement using coal gangue-based limestone-calcined clay cement (LC3). Finite element (FE) models of rural raw-soil architecture with a colored-steel roof (RACSR) were established. The effect of modified soil type and seismic character on the vulnerability of single-story raw-soil structures was investigated using probabilistic seismic demand (PSD) analysis. The seismic response characteristics of 80 representative sequences were comparatively investigated when subjected to northwest clay (raw soil) of China, fiber and stone-improved clay (modified soil), and coal gangue-based limestone-calcined clay cement (LC3 soil). The maximum interstory drift angle (ISDAmax) was lower in the LC3 soil model and the modified soil model compared to the raw-soil model. The use of LC3 soil improves structural resistance and reduces the damage probability of a structure, and the influence of different ultimate failure states on the vulnerability of the raw-soil structure was studied.

scholarly journals Seismic Vulnerability Evaluation of a Three-Span Continuous Beam Railway Bridge

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Chongwen Jiang ◽  
Biao Wei ◽  
Dianbin Wang ◽  
Lizhong Jiang ◽  
Xuhui He
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Seismic Isolation ◽  
Seismic Vulnerability ◽  
Element Model ◽  
Seismic Demand ◽  
Continuous Beam ◽  
Railway Bridge ◽  
Demand Model ◽  
Probabilistic Seismic Demand

In order to evaluate the seismic vulnerability of a railway bridge, a nonlinear finite element model of typical three-span continuous beam bridge on the Sichuan-Tibet railway in China was built. It further aimed at performing a probabilistic seismic demand analysis based on the seismic performance of the above-mentioned bridge. Firstly, the uncertainties of bridge parameters were analyzed while a set of finite element model samples were formulated with Latin hypercube sampling method. Secondly, under Wenchuan earthquake ground motions, an incremental dynamic method (IDA) analysis was performed, and the seismic peak responses of bridge components were recorded. Thirdly, the probabilistic seismic demand model for the bridge principal components under the prerequisite of two different kinds of bearing, with and without seismic isolation, was generated. Finally, comparison was drawn to further ascertain the effect of two different kinds of bearings on the fragility components. Based on the reliability theory, results were presented concerning the seismic fragility curves.

Univariate Fragility Models for Seismic Vulnerability Assessment of Refinery Piping Systems

2017 ◽  
Author(s):  
Stefano Caprinozzi ◽  
Mohammad M. Ahmed ◽  
Fabrizio Paolacci ◽  
Oreste S. Bursi ◽  
Vincenzo La Salandra
Keyword(s):  
Seismic Vulnerability ◽  
Critical Role ◽  
Demand Analysis ◽  
Piping System ◽  
Seismic Demand ◽  
Support Structure ◽  
Probabilistic Seismic Demand Analysis ◽  
Piping Systems ◽  
Damage States ◽  
Probabilistic Seismic Demand

Piping systems of energy industries in oil & gas play a critical role in meeting the increasing global energy demand. A great portion of these pipelines is located in high seismic-prone areas. Such systems have been found to be quite vulnerable to seismic events. Current seismic design approaches to piping systems are mainly based on the allowable stress method, even though more modern design methods are currently available for buildings or nuclear power plants; for example, the Performance-Based Earthquake Engineering (PBEE) framework has not been applied yet to piping systems and relevant structures. In this respect, both information about the quantification of limit states for pipes and adequate non-linear structural models for seismic analysis of piping systems and relevant structures are very limited. One of the key ingredients of PBEE approach for the assessment of the seismic vulnerability of existing structures is the evaluation of fragility curves, namely the probability of exceeding a certain level of damage for a given seismic intensity measure (IM). However, the contributions in the literature on this delicate aspect are very limited. This paper deals with such a problem by using a very popular method, namely the Cloud Analysis, originally developed as a method for probabilistic seismic demand analysis of civil structures. This method is here applied to a typical piping system for process plants. For this purpose, the structure is properly modelled, especially support structure and pipe, including pipe fittings like elbows and bolted flange joints. Using natural accelerograms selected from the PEER database and in accordance with given hazard conditions, the probabilistic seismic demand analysis is performed adopting different engineering demand parameters (EDP) consistent with the damage states expected in the pipes and fittings and in the support structure. According to the results of experimental tests campaign performed in the past by some of the authors on flanged joints, and elbows, different damage states (leakage, yielding, rupture) have been identified and related to the corresponding EDP and the corresponding probability of exceeding has been determined by assuming a lognormal distribution of the response. The analysis intends to recognise the most probable damage condition in a refinery piping system subjected to a seismic input.

scholarly journals Experimental Study on Consolidation-Creep Behavior of Subgrade Modified Soil in Seasonally Frozen Areas

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5138
Author(s):  
Fuyu Wang ◽  
Weichen Pang ◽  
Ziqi Li ◽  
Haibin Wei ◽  
Leilei Han
Keyword(s):  
Experimental Study ◽  
Fly Ash ◽  
High Strength ◽  
Crumb Rubber ◽  
Climatic Conditions ◽  
Waste Utilization ◽  
Road Design ◽  
Creep Characteristics ◽  
Modified Fly Ash ◽  
Modified Soil

Frost heaving and boiling are the most common road disorders due to the special climatic conditions in a seasonal frozen area. From the perspective of controlling road disorders in seasonally frozen areas and making effective use of industrial waste residue, two kinds of subgrade modified soil—crumb rubber modified fly ash soil (CRFS) and oil shale waste residue modified fly ash soil (OSFS)—were proposed by the research group. The research results proved that the two new subgrade fillers both have excellent engineering characteristics in cold areas, such as high strength and low thermal conductivity, and both have the function of waste utilization, giving them broad application prospects. In road engineering, the instability of slopes and retaining walls and the uneven settlement of the subgrade are closely related to soil creep, which are problems that cannot be ignored in road design and use. As a new material to treat road disorders in seasonally frozen areas, more attention should be paid to the continuous deformation property of modified soil under long-term load. The study on the creep characteristics of the modified soil can provide reliable parameters for the design of the modified soil subgrade and predict the settlement of the subgrade after construction, which is of great significance to the stability of the subgrade. In this paper, an experimental study on the consolidation–creep characteristics of two kinds of subgrade modified soil in a seasonal frozen region was carried out, the relationship between modified soil deformation and time is discussed, and the effects of different moisture contents and compaction degrees on the creep characteristics of modified soil were analyzed. The test results provide parameters for the engineering design of modified soil subgrade and provide data support for the popularization and application of modified soil in seasonally frozen subgrade.

Simulation of ground‐penetrating radar waves in a 2-D soil model

Geophysics ◽  
1996 ◽  
Vol 61 (4) ◽  
pp. 1034-1049 ◽  
Author(s):  
David A. Casper ◽  
K ‐J. Samuel Kung
Keyword(s):  
Ground Penetrating Radar ◽  
Flow Simulation ◽  
Absorbing Boundary Conditions ◽  
Absorbing Boundary ◽  
Background Medium ◽  
Soil Model ◽  
Soil Structures ◽  
Homogeneous Background ◽  
Ground Penetrating ◽  
Radar Wave

We have developed a pseudospectral forward modeling algorithm for ground‐penetrating radar (GPR) based on an explicit solution of the 2-D lossy electromagnetic wave equation. Complex soil structures can be accommodated with heterogeneous spatial distributions of both wave velocity and electrical conductivity. This algorithm uses a Gaussian line source with uniform directivity, and there are conductive buffer regions surrounding the soil model to approximate absorbing boundary conditions. Three soil models are used to illustrate different aspects of radar wave propagation. The first model is lossless with homogeneous layers imbedded in a homogeneous background medium, the second model has the same lossless layers in a lossy background medium, and the third model is lossless and uses a nonsaturated water flow simulation to create a complex spatial velocity distribution. Two separate simulations with different source frequencies are presented for each soil model. Results indicate that higher frequency GPR will produce a sharper wavelet and can map soil layering structures with high resolution. In a conductive soil, however, higher frequencies attenuate more rapidly and the radar may not detect deeper layers.

scholarly journals Mechanical and permeation response characteristics of basalt fibre reinforced tailings to different reinforcement technologies: an experimental study

2021 ◽  
Vol 8 (9) ◽  
pp. 210669
Author(s):  
Jianzhong Liu ◽  
Han Yang ◽  
Dongming Zhang ◽  
Yun Wang ◽  
Weijing Xiao ◽  
...  
Keyword(s):  
Experimental Study ◽  
Permeability Coefficient ◽  
Friction Angle ◽  
Dam Failure ◽  
Tailings Dam ◽  
Compression Index ◽  
Basalt Fibre ◽  
Optimal Length ◽  
Response Characteristics ◽  
Soil Structures

Tailings dam is a man-made hazard with high potential energy; dam failure would cause great losses to human lives and properties. However, the limitations of conventional reinforcement methods like geosynthetic make it easy to slide along the weak structural plane. In this paper, we innovatively added basalt fibre (BF) with different lengths ( l ) and contents ( ω ) into tailings to study its mechanical and permeation characteristics. The results indicate that BF can improve the shear strength ( τ ), cohesion ( c ) and compression index ( C c ) of tailings, but it has little effect on internal friction angle ( φ ). When l is constant, τ , c and C c are positively correlated with ω . One notable phenomenon is that τ and c do not constantly increase with l when ω is constant, but obtain the maximum under the optimal length of 6 mm. Moreover, when ω > 0.6%, permeability coefficient ( k ) is greater than that of the original tailings and the sensitivity of c , φ , τ , C c , k to fibre content is greater than that of length. The research results facilitate the understanding of BF reinforced tailings, and could serve as references for improving the safety of tailings dam and other artificial soil slopes or soil structures.

scholarly journals Probabilistic Seismic Demand Analysis of Soil Nail Wall Structures Using Bayesian Linear Regression Approach

2021 ◽  
Vol 13 (11) ◽  
pp. 5782
Author(s):  
Mahdi Bayat ◽  
Amir Homayoon Kosarieh ◽  
Mehran Javanmard
Keyword(s):  
Fragility Curves ◽  
Intensity Measure ◽  
Intensity Measures ◽  
Performance Levels ◽  
Soil Nail ◽  
Soil Model ◽  
Wall Structures ◽  
Probabilistic Seismic Demand ◽  
Soil Nail Wall ◽  
Hardening Soil Model

This paper presents the seismic analytic fragility curve of soil nail wall structures. The numerical modeling procedure of the soil nail wall is presented and discussed in detail. Nonlinear elements have been used to provide an accurate finite element modeling of the soil nail wall. The effect of different soil modeling approaches is studied. Detailed procedures to select an efficient intensity measure are presented. Analytical fragility curves for the different performance levels of the soil nail wall are developed. Detailed techniques have been used to generate accurate soil modeling, such as the Mohr-Coulomb model (MC), Hardening Soil model (HS), and Hardening Soil model with Stiffness effect from small strains (HSS), and these are studied. Incremental dynamic analysis (IDA) is implemented to capture the response of the wall from linear to nonlinear levels. The efficiency of the two common intensity measures is studied (PGA and Sa(T1,5%)). It has been demonstrated that HSS and HS models are more reliable techniques for soil modeling. Two common intensity measures are studied, and the efficiency and the sufficiency of them are compared. It has been suggested that Sa(T1,5%) is a more efficient intensity measure than PGA for soil nail structures due to less depression in the IDA results. Different performance levels were defined to develop analytical fragility curves for different damage states.

scholarly journals Mechanism on Activation of Coal Gangue Admixture

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Jixi Chen ◽  
Xiao Guan ◽  
Mengyu Zhu ◽  
Jie Gao
Keyword(s):  
Evaluation Method ◽  
Particle Surface ◽  
Waste Utilization ◽  
Coal Gangue ◽  
Mineral Admixture ◽  
Activation Mechanism ◽  
Activation Effect ◽  
Mortar Strength ◽  
Chemical Activator ◽  
Secondary Hydration

Coal gangue, an industrial waste, is rich in silicon and aluminum phase and may be used as a mineral admixture in concrete after moderately stimulating activity, allowing for efficient solid waste utilization. This study used a mortar strength and activity evaluation method to investigate single or compound activation methods to find the optimum activation method of coal gangue. FLIR, XRD, and SEM were used to investigate the activation mechanism of different modes, providing a theoretical foundation for the study of coal gangue as a concrete admixture. Results showed that mechanical ball milling, microwave, and chemical activator could activate coal gangue, and the composite activation effect was the best. The fineness of the coal gangue powder was more than 300 mesh, according to the optimal compounding method. Accordingly, the particle surface was smooth, the internal defects were reduced, and the microwave irradiation temperature was 700°C–800°C, causing the coal gangue particles to form a bonding surface and gradually agglutinate and densify. Meanwhile, the layered structure of kaolin minerals was destroyed, and a significant amount of glassy active SiO2 and Al2O3 was produced, enhancing the gel ability and activity of coal gangue. Finally, 8% Ca(OH)2 was added in the production of mortar specimens, which increased the alkalinity of the slurry, stimulated the rapid cracking and secondary hydration of the coal gangue, and enhanced the strength of mortar. At this time, the activity rate of coal gangue powder reached the highest, which was 90.5%.

Retrofit of Masonry Buildings through Seismic Dampers

2019 ◽  
Vol 817 ◽  
pp. 293-300
Author(s):  
Babak Jafarzad Eslami ◽  
Andrea Del Grosso
Keyword(s):  
Seismic Vulnerability ◽  
Passive Control ◽  
Failure Modes ◽  
Base Isolation ◽  
Masonry Walls ◽  
Isolation System ◽  
Finite Element Software ◽  
Structural Resistance ◽  
Fixed Base ◽  
Base Isolation System

After the recent earthquakes occurred in some cities in Iran, such as Bam and Kermanshah, the engineering community was forced to pay special attention to the seismic vulnerability of traditional structures. Unreinforced masonry walls exhibit poor seismic performance under moderate and high seismic demand, due to the rapid degradation of stiffness. The development of effective techniques for the strengthening of these walls is an urgent need. The Base Isolation System (BIS) provides solutions to mitigate seismic hazard [1]. In this work, the seismic vulnerability of heritage masonry walls is assessed by conducting extensive numerical studies on both unreinforced (fixed-base) and reinforced (Base Isolation System) masonry walls. In this manner, modeling and analysis are conducted using standard finite element software, ABAQUS 6.13, and results of fixed-base masonry wall and similar base-isolated walls retrofitted with laminated rubber bearings are compared. Nonlinear time history analyses (using the actual Bam earthquake), which enable description of the pre-peak and post-peak behavior of walls, have been used to describe the behavior of structures.Finally, comparison of the failure modes between unreinforced and reinforced masonry walls reveals efficiency of using the rubber bearing isolation (passive control vibration devices) for a reduction in acceleration and an increase in the structural resistance to earthquake excitations [2].

Smoothing Facilitates the Detection of Coupled Responses in Psychophysiological Time Series

2000 ◽  
Vol 14 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Joni Kettunen ◽  
Niklas Ravaja ◽  
Liisa Keltikangas-Järvinen
Keyword(s):  
Time Series ◽  
Type I Error ◽  
Electrodermal Activity ◽  
Moving Average ◽  
Type I ◽  
Facial Electromyography ◽  
Response Characteristics ◽  
Smoothing Methods ◽  
Response Systems ◽  
Different Response

Abstract We examined the use of smoothing to enhance the detection of response coupling from the activity of different response systems. Three different types of moving average smoothers were applied to both simulated interbeat interval (IBI) and electrodermal activity (EDA) time series and to empirical IBI, EDA, and facial electromyography time series. The results indicated that progressive smoothing increased the efficiency of the detection of response coupling but did not increase the probability of Type I error. The power of the smoothing methods depended on the response characteristics. The benefits and use of the smoothing methods to extract information from psychophysiological time series are discussed.

Interpreting Open- and Closed-Loop Transfer Relations Between Cardiorespiratory Parameters: Lessons Learned from a Computer Model of Beat-to-Beat Cardiovascular Regulation

1997 ◽  
Vol 36 (04/05) ◽  
pp. 237-240
Author(s):  
P. Hammer ◽  
D. Litvack ◽  
J. P. Saul
Keyword(s):  
Computer Model ◽  
Closed Loop ◽  
Computer Models ◽  
Cardiovascular Regulation ◽  
Cardiovascular Control ◽  
Lessons Learned ◽  
Multiple Systems ◽  
Response Characteristics ◽  
Similarities And Differences

Abstract:A computer model of cardiovascular control has been developed based on the response characteristics of cardiovascular control components derived from experiments in animals and humans. Results from the model were compared to those obtained experimentally in humans, and the similarities and differences were used to identify both the strengths and inadequacies of the concepts used to form the model. Findings were confirmatory of some concepts but contrary to some which are firmly held in the literature, indicating that understanding the complexity of cardiovascular control probably requires a combination of experiments and computer models which integrate multiple systems and allow for determination of sufficiency and necessity.

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