Loading...
Search for:
bayesian-regression
0.01 seconds
Risk-based Approach to Account for Soil-Structure Interaction in Seismic Design of Building Structures
,
Ph.D. Dissertation
Sharif University of Technology
;
Ghannad, Mohammad Ali
(Supervisor)
;
Mahsuli, Mojtaba
(Supervisor)
Abstract
This paper proposes a novel probabilistic approach to account for soil-structure interaction (SSI) in the seismic design of building structures. In this approach, an SSI response modification factor, RSSI, is introduced to capture SSI effects on the seismic performance of structures. The proposed procedure quantifies RSSI such that the probability distribution of the collapse capacity of the structure designed to account for SSI concurs with that of the structure designed using the default fixed-base provisions. The proposed approach is employed for special steel moment frame buildings with surface foundation. A surrogate single degree of freedom (SDOF) system is developed in this study and...
Water Quality Monitoring Using Remote Sensing: A Case Study of Gorgan Bay
, M.Sc. Thesis Sharif University of Technology ; Tajrishi, Massoud (Supervisor)
Abstract
Surface water quality management needs water contaminants monitoring and information about water quality parameters. Field measurement is a costly, time-consuming procedure that limits information about the whole surface of a water body. Remote sensing methods are valuable ways that prepare water quality information using different characteristics between reflectance detected from each parameter. This study aimed to investigate the water quality parameters of Gorgan Bay using field sampling and a feasibility study using Landsat-8 and Sentinel-2 images to estimate the spatial and temporal changes of optically active parameters (such as sea surface temperature (SST), salinity, electrical...
Probabilistic Evaluation of Seismic Soil Liquefaction in Sands Using Cone Penetration Test (CPT)Data
, M.Sc. Thesis Sharif University of Technology ; Ahmadi, Mohammad Mehdi (Supervisor)
Abstract
More than half a century has passed since the start of research on seismic liquefaction phenomenon in cohesionless soils, and various researchers has proposed different correlations for liquefaction prediction based on in situ tests. However, there still exists a great uncertainty in liquefaction prediction correlations, and liquefaction still occurs in different parts of the world. Hence, the main objective of this research is to reduce uncertainty in seismic liquefaction initiation correlations. While the technical literature indicates that soil resistance can alter due to liquefaction and shaking events and soil resistance after the liquefaction is not necessarily indicative of it prior...
Effect of applied stress and bar characteristics on the short-term creep behavior of FRP bars
, Article Construction and Building Materials ; May , Volume 171 , 2018 , Pages 960-968 ; 09500618 (ISSN) ; Bazli, M ; Ashrafi, H ; Vatani Oskouei, A ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
This paper presents the creep behavior of various FRP (GFRP, CFRP, and hybrid) bars in order to investigate the effects of different parameters, including the applied stress levels, bar diameter, and the type of fiber and resin in the creep behavior of FRP bars. The creep strains versus time curves were experimentally obtained for 83 days. Moreover, a statistical study, including analysis of variance (ANOVA) and linear Bayesian regression was conducted to investigate the contribution of the studied parameters. The results showed that in GFRP bars the ratio of ultimate creep strain to the initial elastic strain decreased when the applied stresses on the bars exceeded 30% of their ultimate...
Experimental investigation and probabilistic models for residual mechanical properties of GFRP pultruded profiles exposed to elevated temperatures
, Article Composite Structures ; Volume 211 , 2019 , Pages 610-629 ; 02638223 (ISSN) ; Houshmand Khaneghahi, M ; Ahmadie Amiri, H ; Esmaeilpour Estekanchi, H ; Ozbakkaloglu, T ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Here, we investigate the influence of elevated temperatures with negligible ambient oxygen on mechanical properties of various embedded glass fiber reinforced polymer (GFRP) profiles, as well as the application of a predictive Bayesian model for predicting these properties. Both the flexural and compressive properties of FRP profiles were investigated through the tests of I-shaped and box-shaped profiles. To determine the impact of low and high elevated temperature, the profiles were exposed to a wide range of temperatures (i.e., 25–550 °C); effects of the exposure time were also investigated. Experiments showed that specimens exposed to higher elevated temperatures for longer time periods...
Probabilistic modeling framework for prediction of seismic retrofit cost of buildings
, Article Journal of Construction Engineering and Management ; Volume 143, Issue 8 , 2017 ; 07339364 (ISSN) ; Mahsuli, M ; Talebiyan, H ; Kashani, H ; Sharif University of Technology
Abstract
This study presents a framework that utilizes Bayesian regression to create probabilistic cost models for retrofit actions. Performance improvement is the key parameter introduced in the proposed framework. The incorporation of this novel feature facilitates the characterization of retrofit cost as a continuous function of the desired performance improvement. Accounting for the performance gained from retrofit enables the use of the models in determining the optimal level of retrofit. Furthermore, accounting for the model uncertainty facilitates the use of the models in risk and reliability analyses. The proposed framework is applied to create seismic retrofit cost models for masonry school...
Assessment of the urban heat island in the city of Tehran using reliability methods
, Article Atmospheric Research ; Volume 225 , 2019 , Pages 144-156 ; 01698095 (ISSN) ; Moghim, S ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Climate change affects temperature, magnitude, and also the duration of the Urban Heat Island (UHI), which has severe impacts on the environment, communities, and the people's lives. This study evaluates UHI formation in the city of Tehran (Iran) using a reliability framework, which is able to include related uncertainties into the modeling procedure. First, 2 km air temperature field from Weather and Research Forecasting (WRF) model is downscaled to a 50 m grid spacing using a probabilistic downscaling method, which combines inverse distance weighting (IDW) interpolation and a Bayesian regression model. This downscaling method not only can produce a long record of the fine resolution of the...
Effect of intumescent paint coating on mechanical properties of FRP bars at elevated temperature
, Article Polymer Testing ; Volume 71 , 2018 , Pages 72-86 ; 01429418 (ISSN) ; Pournamazian Najafabadi, E ; Shoaei, P ; Vatani Oskouei, A ; Sharif University of Technology
Abstract
This paper investigates the influence of intumescent paint on the performance of FRP bars subjected to low (25–450 °C) and severe (450–800 °C) elevated temperatures. In this research, glass and carbon FRP bars with epoxy resin and coated with nitrogen-based intumescent paint were used. In addition to the temperature effects, a variety of FRP bar diameters were employed to determine its effect on the tensile behavior of FRP bars in the presence of intumescent paint. Further, Bayesian regression methods and ANOVA (ANalysis Of VAriance) were applied on the results to develop a predictive model form and quantify the contribution of the variables in the tensile performance of FRP bars,...
Experiments and probabilistic models of bond strength between GFRP bar and different types of concrete under aggressive environments
, Article Construction and Building Materials ; Volume 148 , 2017 , Pages 429-443 ; 09500618 (ISSN) ; Ashrafi, H ; Vatani Oskouei, A ; Sharif University of Technology
Abstract
Bond durability of FRP bars and concrete is an important issue to the overall integrity and long-term performance of a strengthening structure. This paper examines the bond durability of GFRP bars embedded in different types of concrete (Normal, self-compacting, light weight, and high strength) exposed to aggressive environments, namely, sea water, alkaline, and acid. A total of 132 specimens were tested in direct pull-out. The development lengths of both control and conditioned specimens were obtained and compared to the current standards. The results revealed bond strength reductions of 0–21% for the light weight, 1–16% for the normal, 5–9% for the high strength, and 4–12% for the...
Effect of thickness and reinforcement configuration on flexural and impact behaviour of GFRP laminates after exposure to elevated temperatures
, Article Composites Part B: Engineering ; Volume 157 , 2019 , Pages 76-99 ; 13598368 (ISSN) ; Ashrafi, H ; Jafari, A ; Zhao, X.-L ; Gholipour, H ; Oskouei, A. V ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
This study investigates the flexural and impact behaviour of GFRP laminates after exposure to elevated temperatures. The effect of fibre's length and orientation, laminate's thickness, and exposure time is studied. A total number of 540 tests in terms of three-point bending and Charpy impact tests were conducted to obtain the mechanical properties. In addition, SEM analyses were carried out to investigate the degradation mechanisms. Finally, statistical study was conducted to investigate the contribution of each variable and develop probabilistic models using ANOVA and linear Bayesian regression method. The results showed that generally the flexural and impact properties of GFRP laminates...