Investigating the effects of combinations of irregularities on seismic ductility demands and mean response for four-span RC bridges considering displacement direction

2021 ◽  
Vol 16 (2-3) ◽  
pp. 105-117
Author(s):  
Mohsen Sajed ◽  
Payam Tehrani
Keyword(s):  
Time History ◽  
The Past ◽  
History Analysis ◽  
Different Types ◽  
Displacement Direction ◽  
The Mean ◽  
Support Conditions ◽  
Irregular Bridges ◽  
Ground Motion Records ◽  
The Impact

The effects of combinations of different types of irregularities have not been studied in details in the past and current seismic design codes do not address this issue appropriately. In this research, 76 regular and irregular bridges with irregularities in both superstructure and substructure were designed and evaluated to investigate the impact of combinations of irregularities on the seismic ductility demands. The irregularity parameters considered in this study include irregularities in span arrangement, different lengths of columns, different abutments support conditions and different stiffness of superstructure. The bridges were designed and checked according to AASHTO provisions. Inelastic time history analysis was conducted using OpenSees software and ductility demands in bridge columns for different bridge configurations were predicted. Predictions of ductility demands were based on the mean responses obtained using a number of ground motion records. Finally, the effect of considering displacement directions in predicting the mean bridge response (i.e., using different methods for predicting the mean response) for irregular and regular bridges was investigated. The results indicate that the combinations of irregularities can significantly increase the ductility demands in some cases compared to the case of regular bridges.

scholarly journals Investigating the Use of Natural and Artificial Records for Prediction of Seismic Response of Regular and Irregular RC Bridges Considering Displacement Directions

2021 ◽  
Vol 11 (3) ◽  
pp. 906
Author(s):  
Payam Tehrani ◽  
Denis Mitchell
Keyword(s):  
Seismic Response ◽  
Radial Displacement ◽  
Time History ◽  
Good Prediction ◽  
3D Analysis ◽  
Combination Rules ◽  
Principal Axes ◽  
Artificial Records ◽  
The Mean ◽  
Irregular Bridges

The seismic responses of continuous multi-span reinforced concrete (RC) bridges were predicted using inelastic time history analyses (ITHA) and incremental dynamic analysis (IDA). Some important issues in ITHA were studied in this research, including: the effects of using artificial and natural records on predictions of the mean seismic demands, effects of displacement directions on predictions of the mean seismic response, the use of 2D analysis with combination rules for prediction of the response obtained using 3D analysis, and prediction of the maximum radial displacement demands compared to the displacements obtained along the principal axes of the bridges. In addition, IDA was conducted and predictions were obtained at different damage states. These issues were investigated for the case of regular and irregular bridges using three different sets of natural and artificial records. The results indicated that the use of natural and artificial records typically resulted in similar predictions for the cases studied. The effect of displacement direction was important in predicting the mean seismic response. It was shown that 2D analyses with the combination rules resulted in good predictions of the radial displacement demands obtained from 3D analyses. The use of artificial records in IDA resulted in good prediction of the median collapse capacity.

scholarly journals The Effect of slit-friction hybrid damper on the Performance of Dual System

2019 ◽  
Vol 13 (1) ◽  
pp. 271-280
Author(s):  
Azadeh Khoshkroodi ◽  
Hossein Parvini Sani
Keyword(s):  
Time History ◽  
Steel Structures ◽  
Repair Cost ◽  
Friction Dampers ◽  
History Analysis ◽  
Different Types ◽  
Moment Resisting ◽  
Hybrid Damper ◽  
Large Earthquakes ◽  
Different Levels

Aims: The aim of the present paper is to evaluate the behavior of slit friction hybrid dampers (SFHD) on steel structures. Therefore, the behavior moment resisting steel frames of structures in original stats and structures equipped with hybrid damper with two different types of behavior was analyzed and evaluated. Background: The recent study evaluated the combined effect of shear-friction dampers and slit dampers with measurements of non-uniform strips in seismic protection for different levels of energy. The recent study was carried out a about hybrid dampers, consisting of friction and split dampers in response to small and large earthquakes. Previous results have shown the ability of inactive hybrid systems in improving the reaction of structures to traditional lateral-systems. Kim and Shin showed that structures consisted of hybrid dampers needed less repair cost and time. Methods: Pushover and time history were carried out on original structures and structures equipped with dampers, in 5 and 10 stories structures. Results: Analysis about the probability of collapse showed about 30% and 84%. Conclusion: According to the result, by adding the SFHD, increased stiffness by 17% in retrofitted structures such as drift and displacement of roof decreases by 27% and 20% in push over analysis, respectively. Also, displacement in time history analysis up to 55% reduces in average. Also, the results of the IDA show that adding the SFHD to structures significantly increases by 55% the spectral acceleration capacity in structures.

The distribution and prehistory of Eucalypt diversicolor F. Muell., E. marginata Donn ex Sm., and E. calophylla R. Br. in relation to rainfall

1968 ◽  
Vol 16 (1) ◽  
pp. 125 ◽  
Author(s):  
DM Churchill
Keyword(s):  
Relative Increase ◽  
Temperature Data ◽  
Forest Trees ◽  
The Past ◽  
Peat Deposits ◽  
Close Relationship ◽  
The Mean ◽  
The Impact ◽  
Substantial Change ◽  
Eucalyptus Diversicolor

Fossil pollen of Eucalyptus diversicolor, E. marginata, and E. calophylla has been identified in peat deposits from south-western Australia, where the species are prominent and economically important forest trees. The extant distribution of each species has been surveyed and the presence or absence of each, within and beyond the margins of their ranges, shows a close relationship with the mean rainfall of the wettest and driest months of the year. No such relationship was found with temperature data, and it is evident that the availability of water is a major factor influencing the distribution of these three species. Past changes in the relative eucalypt pollen frequencies have been dated by radiocarbon assay, and the dates appear to cluster around 3000,1200, and 500 B.C. and A.D. 400 and 1200. Charcoal is common in the peat and it is evident that fires have frequently occurred around the sites investigated, for at least the past 5000 years. Many of these fires have severely burnt and truncated the peat deposits. However, charcoal is not always present at levels of substantial change in the pollen frequencies, from which it is concluded that equilibrium between these forest eucalypts and fire has existed for at least the past 7000 years. Fossil evidence of the presence of prehistoric man in Australia predates the period under investigation, but the impact of man on the vegetation was probably limited to his use of fire. From what is known of the moisture requirements of the two species, it seems probable that a climate which favoured a relative increase of the E. diversicolor/E. Calophylla ratio would be much wetter than that which would favour a high E. calophylla/E. diversicolor ratio. This being the case, it is evident from the prehistoric changes in the ratios of these two species that the climate from at least 4000 until 3000 B.C. was wetter than at present, and thereafter it became increasingly dry (maximum dryness at c. 1200 B.C.) until about 500 B.C., when conditions once more became wetter and continued so until A.D. 500; after this a period of rapid drying out is evident until A.D. 1200-1500, when conditions became wetter up to the present day.

scholarly journals The Impact of Improved Thermistor Calibration on the Expendable Bathythermograph Profile Data

2017 ◽  
Vol 34 (9) ◽  
pp. 1947-1961 ◽  
Author(s):  
Marlos Goes ◽  
Elizabeth Babcock ◽  
Francis Bringas ◽  
Peter Ortner ◽  
Gustavo Goni
Keyword(s):  
Small Sample Size ◽  
Heat Content ◽  
Small Sample ◽  
Profile Data ◽  
Expendable Bathythermograph ◽  
Different Types ◽  
Long Term Trends ◽  
The Mean ◽  
The Impact

AbstractExpendable bathythermograph (XBT) data provide one of the longest available records of upper-ocean temperature. However, temperature and depth biases in XBT data adversely affect estimates of long-term trends of ocean heat content and, to a lesser extent, estimates of volume and heat transport in the ocean. Several corrections have been proposed to overcome historical biases in XBT data, which rely on constantly monitoring these biases. This paper provides an analysis of data collected during three recent hydrographic cruises that utilized different types of probes, and examines methods to reduce temperature and depth biases by improving the thermistor calibration and reducing the mass variability of the XBT probes.The results obtained show that the use of individual thermistor calibration in XBT probes is the most effective calibration to decrease the thermal bias, improving the mean thermal bias to less than 0.02°C and its tolerance from 0.1° to 0.03°C. The temperature variance of probes with screened thermistors is significantly reduced by approximately 60% in comparison to standard probes. On the other hand, probes with a tighter weight tolerance did not show statistically significant reductions in the spread of depth biases, possibly because of the small sample size or the sensitivity of the depth accuracy to other causes affecting the analysis.

IMPACT OF KVK TRAINING PROGRAMMES ON KNOWLEDGE AND ADOPTION OF CHICKPEA PRODUCTION INNOVATIONS IN MADHYA PRADESH, INDIA

2015 ◽  
Vol 30 (1) ◽  
Author(s):  
L. K. MEENA ◽  
Lokesh SIROHIYA ◽  
S. KANT ◽  
S. L. BAIRWA ◽  
A. JHAJHARIA
Keyword(s):  
Production Technology ◽  
Madhya Pradesh ◽  
Low Level ◽  
Pulse Crop ◽  
The Past ◽  
The Mean ◽  
Recommended Practices ◽  
Training Programmes ◽  
The Impact

Chickpea is an important pulse crop in India. Its production is stagnating and its variability is increased in the past three decades. The present study is an attempt to examine the impact of KVK Training programmes on knowledge and adoption of Chickpea production technology among participating and non- participating farmers of Sihora block of Jabalpur District Madhya Pradesh. The mean knowledge scores of participating and non-participating respondents about chickpea practices were 23.53 and 16.03 indicating that through training imparted by the KVK, the participating respondents have shown better results over non- participating respondents. Comparatively higher percentages of non- participating respondents were observed in medium and low level of adoption. Overall mean adoption score indicates that respondents have not fully adopted the recommended practices of chickpea crop. Difference in extent of adoption between participating and non-participating respondents was highly significant.

Influence of Non-Linear Properties of Fluid Viscoelastic Properties on Seismic Damping Properties of a Ten Stories Building Using ANSYS Program

2014 ◽  
Vol 658 ◽  
pp. 245-248 ◽  
Author(s):  
Adriana Ionescu ◽  
Mihai Negru ◽  
Cristian Burada
Keyword(s):  
Viscoelastic Fluid ◽  
Time History ◽  
Seismic Energy ◽  
Nonlinear Damping ◽  
Damping Properties ◽  
Damping Property ◽  
History Analysis ◽  
Different Types ◽  
Nonlinear Features ◽  
Fluid Dampers

This paper presents the simulation of the influence of viscoelastic fluid dampers, with nonlinear damping properties, on damping property of a ten stories building structure. The study was made using Finite Elements Method and ANSYS program, on a 3d F.E.M. model. In order to obtain the influence of different types of damping nonlinearities of the viscoelastic fluid dampers on the damping property of the entire structure, there were made different types of simulations using modal analysis and seismic time history analysis. The graphics obtained can be used for determining the nonlinear features of fluid dampers for achieving different degrees of seismic energy dissipation for the analyzed building.

scholarly journals Species Diversity of Oak Stands and Its Significance for Drought Resistance

2018 ◽  
Author(s):  
Jan Kotlarz ◽  
Sylwia Nasiłowska ◽  
Karol Rotchimmel ◽  
Katarzyna Kubiak
Keyword(s):  
Species Diversity ◽  
Satellite Images ◽  
Aerial Images ◽  
Summer Drought ◽  
Different Types ◽  
The Mean ◽  
The Individual ◽  
Pca Algorithm ◽  
The Impact ◽  
Remote Sensing Indices

Drought periods have an adverse impact on the condition of oak stands. Research on different types of ecosystems has confirmed a correlation between plant species diversity and the adverse effects of droughts. The purpose of this study was to investigate the changes which occurred in an oak stand (Krotoszyn Plateau, Poland) under the impact of the summer drought in 2015. We used a method based on remote sensing indices from satellite images in order to detect changes in the vegetation in 2014 and 2015. A positive difference was interpreted as an improvement, whereas a negative one was treated as a deterioration of the stand condition. The Shannon-Wiener species diversity was estimated using an iterative PCA algorithm based on aerial images. We observed a relationship between the species indices of the individual forest divisions and their response to drought. The highest correlation between the index differences and the Shannon-Wiener indices was found for the GNDVI index (+0.74). In addition, correlations were observed between the mean index difference and the percentage shares in the forest divisions of species such as Pinus sylvestris (+0.67 ± 0.08) and Quercus robur (-0.65 ± 0.10). Our results lead us to infer that forest management based on highly diverse habitats is more suitable to meet the challenges in the context of global climatic changes, characterized by increasingly frequent droughts.

GENERATION OF A PAIR OF SURFACE TIME HISTORIES FOR JAKARTA USED FOR EARTHQUAKE RESISTANCE DESIGN OF INFRASTRUCTURES

2015 ◽  
Vol 77 (11) ◽  
Author(s):  
B.M. Hutapea ◽  
M. Asrurifak ◽  
Hendriyawan Hendriyawan ◽  
Masyhur Irsyam
Keyword(s):  
Ground Surface ◽  
Time History ◽  
Hazard Maps ◽  
Surface Time ◽  
History Analysis ◽  
Earthquake Design ◽  
Time Histories ◽  
Design Loads ◽  
Dynamic Time ◽  
The Impact

It is not the earthquake but the collapse of the building and infrastructure that will cause the damage and the loss of human lives. To mitigate these hazards, the building and infrastructure need to be designed such that will not collapse due to earthquake. This paper presents the procedure for generating time histories at ground surface for Jakarta area. Required data to generate these modified time histories were extracted from the Team for Revision of Seismic Hazard Maps of Indonesia 2010. The results are used as input motions in dynamic time history analysis for predicting earthquake design loads for infrastructures, such as bridges such that those structures can be designed to bear the impact of an earthquake and prevent collapse

scholarly journals THE IMPACT OF NEW TARGETING METHODS IN THE CANCER THERAPY

2019 ◽  
pp. 1-6
Author(s):  
ZAKARIYA AL-MASHHADANI ◽  
RUA A. NASER ◽  
MUNAF H. ZALZALA
Keyword(s):  
Cancer Therapy ◽  
Literature Review ◽  
Information Sources ◽  
Rapid Development ◽  
Malignant Cell ◽  
Cancer Targeting ◽  
The Past ◽  
Toxic Drug ◽  
Different Types ◽  
The Impact

Rapid development has achieved in treating tumor to stop malignant cell growth and metastasis in the past decade. Numerous researches have emerged to increase potency and efficacy with novel methods for drug delivery. The main objective of this literature review was to illustrate the impact of current new targeting methods to other previous delivering systems to select the most appropriate method in cancer therapy. This review first gave a brief summary of cancer structure and highlighted the main roles of targeting systems. Different types of delivering systems have been addressed in this literature review with focusing on the latest carrier derived from malarial protein. The remarkable advantages and main limitations of the later have been also discussed. PubMed and Science Direct were the main search engines that have been used as information sources to prepare this review. Articles related to cancer targeting system, active and passive processes, current nanoparticles, antibody carriers, and current novel cancer carriers were used as sources in this review. Important points from many references published in the last decade (2008-2018) were selected and included. Several targeting methods were introduced to enhance the efficacy and tolerability of the toxic drug by active and passive processes, but there is still no conclusive carrier without certain drawbacks. A combination of targeting methods probably shows the most appropriate choice for increasing selectivity and safety of anticancer drugs via reducing the concentration of carriers used.

The impact of explicit instruction on different types of linguistic properties

2019 ◽  
Author(s):  
Joana Teixeira
Keyword(s):  
Explicit Instruction ◽  
The Past ◽  
European Portuguese ◽  
Different Types ◽  
L2 Development ◽  
Post Test ◽  
Syntactic Properties ◽  
Locative Inversion ◽  
Discourse Interface ◽  
The Impact

Abstract Over the past decades, L2 research has shown that properties involving the syntax-discourse interface are typically more complex to acquire than strictly syntactic properties. To determine whether the complexity of the target property moderates the effectiveness of explicit instruction, this study investigates the impact of explicit instruction on the development of a syntactic property (the ungrammaticality of free inversion) and a syntax-discourse property (the unacceptability of locative inversion with informationally heavy verbs) in L1 European Portuguese-L2 English (B2 and C1 levels), using a pre-test/post-test design. Results reveal that instruction only produced lasting effects when it targeted syntax and learners were at the C1 level. These results indicate that syntax may be more permeable to instructional effects than the syntax-discourse interface and that the effectiveness of explicit instruction depends on learners’ stage of L2 development.

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