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Showing 28 results for Modeling

J. S. Yi, C. W. Koo, S. H. Park, O. K. Kwon,
Volume 11, Issue 1 (3-2013)
Abstract

Construction industry consists of several phases in which a variety of stakeholders are involved. As construction projects are becoming larger, more complex and more diverse, the design phase has been more important factor for the success of projects than ever before. However, it is considered that most of design work occurred in actual design process is intangible. Such recognition makes the design phase more unsystematic and arbitrary, which finally weakens the competitiveness of whole project. In order to solve these problems, this study developed a web-based system for integrated design management (IDMS) which consists of 8 modules including design document, schedule, quality, and building permit management. This section is intended to validate the system implementation and its effectiveness. Two characteristics have made this research significantly different from previous studies. First of all, users of the system including architects and other design professionals were continuously involved starting from the development phase to the validation phase. The other unique characteristic is that the actual design project was applied as a test bed in the final verification stage. The research team applied the actual data which had been generated while each business process, and verified the effectiveness of system implementation. The authors expect that such a user-centered approach enable the system more robust and effective.
F. Nasirzadeh, M. Khanzadi, A. Afshar, S. Howick,
Volume 11, Issue 1 (3-2013)
Abstract

This research presents a dynamic mathematical system for modeling and simulating the quality management process in construction projects. Through sets of cause and effect feedback loops, all factors that internally and externally affect the quality management process are addressed. The proposed system integrates fuzzy logic with system dynamics simulation scheme to consider the uncertainties associated with the model parameters and estimation of the extra cost and time due to quality defects. Quantification of the consequences of the quality failures is performed based on the α-cut representation of fuzzy numbers and interval analysis. The proposed approach is efficient in modeling and analyzing a quality management process which is complex and dynamic in nature and involves various uncertainties. The proposed approach is implemented in a real submarine water supply pipe line project in order to evaluate its applicability and performance. The negative impacts resulting from quality failures are simulated. These negative impacts are mitigated by the implementation of alternative solutions.
M. Mortazavi Zanjani, A. Soroush,
Volume 11, Issue 2 (11-2013)
Abstract

This paper presents results of a thorough study on the phenomenon of rupture propagation of reverse faults from the bedrock

foundation through homogeneous clayey embankments, mainly at the end of construction, with complementary analyses for the

steady state seepage through the embankment. The study is performed by means of numerical analyses with a nonlinear Finite

Element Method, verified beforehand through simulating fault propagations in an existing horizontal soil layer experiment.

Multiple cases considering three slopes & three clayey soils for the embankment and five fault dip angles, activated in several

locations of base of the embankment, are analyzed. The results show that ruptures in the embankment follow optimal paths to

reach the surface and their near-surface directions are predictable with respect to corresponding theories of classical soil

mechanics. Various types of rupture in the embankment are produced on the basis of the rupture types, the embankment base is

divided into three distinguishable zones, which can be used for interpretation of fault ruptures behavior. The effects of materials

and slope of the embankment, fault dip angle, and fault’s point of application in the bedrock-soil interface on the rupture paths

are studied in depth.


Y.y. Chang, C.j. Lee, W.c. Huang, W.j. Huang, M.l. Lin, W.y. Hung, Y. H. Lin,
Volume 11, Issue 2 (11-2013)
Abstract

This study presents a series of physical model tests and numerical simulations using PFC2D (both with a dip slip angle=60° and

a soil bed thickness of 0.2 m in model scale)at the acceleration conditions of 1g, 40g, and 80 g to model reverse faulting. The soil

deposits in prototype scale have thicknesses of 0.2 m, 8 m, and 16 m, respectively. This study also investigates the evolution of a

surface deformation profile and the propagation of subsurface rupture traces through overlying sand. This study proposes a

methodology for calibrating the micromechanical material parameters used in the numerical simulation based on the measured

surface settlements of the tested sand bed in the self-weight consolidation stage. The test results show that steeper surface slope

on the surface deformation profile, a wider shear band on the major faulting-induced distortion zone, and more faulting appeared

in the shallower depths in the 1-g reverse faulting model test than in the tests involving higher-g levels. The surface deformation

profile measured from the higher-g physical modeling and that calculated from numerical modeling show good agreement. The

width of the shear band obtained from the numerical simulation was slightly wider than that from the physical modeling at the

same g-levels and the position of the shear band moved an offset of 15 mm in model scale to the footwall compared with the results

of physical modeling.


H. Ghiassian, M. Jalili, I. Rahmani, Seyed M. M. Madani,
Volume 11, Issue 4 (12-2013)
Abstract

The concept of Geosynthetic Cellular Systems (GCS) has recently emerged as a new method in construction of breakwaters and coastal protective structures. The method potentially has significant advantages compared to conventional systems from the standpoint of constructability, cost effectiveness, and environmental considerations. This paper presents the results of physical model testing on the hydraulic responses of GCS structures under wave action. A series of model tests were carried out in a wave flume on GCS models with different shapes and soil types, subjected to various wave characteristics. Horizontal wave forces acting on the models were measured at different elevations. The maximum horizontal force in each test was calculated and compared with conventional formula of predicting wave pressure on breakwaters. The results show that Goda’s equation overestimates the hydrodynamic water pressure on these structures. This can be attributed to the influence of seeping water through the GCS models because of relative permeability of the GCS.
K. J. Tu, Y. W. Huang,
Volume 11, Issue 4 (12-2013)
Abstract

The decisions made in the planning phase of a building project greatly affect its future operation and maintenance (O&M) cost. Recognizing the O&M cost of condominiums’ common facilities as a critical issue for home owners, this research aims to develop an artificial neural network (ANN) O&M cost prediction model to assist developers and architects in effectively assessing the impacts of their decisions made in the planning phase of condominium projects on future O&M costs. A regression cost prediction model was also developed as a benchmark model for testing the predictive accuracy of the ANN model. Six critical building design attributes (building age, number of apartment units, number of floors, average sale price, total floor area, and common facility floor area) which are usually available in the project planning phase, were identified as the input factors to both models and average monthly O&M cost as the output factor. 55 of the 65 existing condominium properties randomly selected were treated as the training samples whose data were used to develop the ANN and regression models the other ten as the test samples to compare and verify the predictive performance of both models. The study results revealed that the ANN model delivers more accurate and reliable cost prediction results, with lower average absolute error around 7.2% and maximum absolute error around 16.7%, as compared with the regression model. This study shows that ANN is an effective method in predicting building O&M costs in the project planning phase. Keywords: Project management, Facility management, Common facilities, Cost modeling.
P. Ramadoss,
Volume 12, Issue 1 (3-2014)
Abstract

Abstract: This paper presents the influence of adding steel fibers and incorporation of silica fume on the mechanical properties of high-strength concrete. The variables investigated were steel fiber volume fraction (0 to 1.5%), silica fume replacement (5, 10 and 15%) and water-to-binder ratio (0.25, 0.30, 0.35 and 0.40). The influence of fiber content in terms of fiber reinforcing index on the compressive and splitting tensile strengths of high-strength steel fiber reinforce concrete (HSFRC) is presented. The use of silica fume increased both the compressive and splitting tensile strengths of concrete at 28 days. On the other hand, the addition of crimped steel fiber into high-strength concrete improves splitting tensile strength significantly. Based on the test data, using regression analysis, empirical expression to predict 28-day tensile strength of HSFRC in terms of fiber reinforcing index was developed and the absolute variation and integral absolute error (IAE) obtained was 3.1% and 3.3, respectively. The relationship between splitting tensile and compressive strength of SFRC was reported with regression coefficient (r) = 0.9. The experimental values of previous researchers were compared with the values predicted by the model and found to predict the values quite accurately.
M. Effati, M. A. Rajabi, F. Samadzadegan, Sh. Shabani,
Volume 12, Issue 3 (9-2014)
Abstract

Road transportation by way of automobiles is a very convenient means of transportation. Today, the most detrimental consequence of developing transportation systems in a country is traffic accident that places a huge financial burden on society. This paper investigates the role of information systems in transportation safety that leads to improved planning and operation of the transportation system through the application of new technologies. Current methods for identification of segments of roads with high potential of accident are based on statistical approaches. Since there are not accident records for newly built roads, these methods cannot be used for regional roads that are recently built. This paper presents a GIS based Neuro-Fuzzy modeling for identification of road hazardous zones. The results of proposed approach are compared with statistical methods. It is shown that this method is a cheaper but at the same time robust means of analyzing the level of hazard associated with each road segment under consideration, specially when data are uncertain and incomplete.
M. Zare, A. Eslami,
Volume 12, Issue 4 (12-2014)
Abstract

Physical modeling for study of deep foundations can be performed in simple chambers (1g), calibration chambers (CC),

and centrifuge apparatus (ng). These common apparatus face certain limitations and difficulties. Recently, Frustum Confining

Vessels (FCV) have been evolved for physical modeling of deep foundations and penetrometers. Shaped as the frustum of a

cone, this device applies steady pressure on its bottom and creates a linear stress distribution along its vertical central core.

This paper presents the key findings in FCV, as developed in AUT. The FCV has a height of 1200 mm, with top and bottom

diameters of 300 and 1300 mm, respectively. By applying bottom pressure up to 600 kPa, the in-situ overburden stress

conditions, equivalent up to 40 m soil deposits, become consistent with the embedment depth of commonly used piles.

Observations indicated that a linear trend of stress distribution exists, and this device can create overburden stress in the

desired control volume along the central core. Moreover, a couple of compressive and tensile load tests were performed on

steel model piles driven in sand with a length of 750 mm, and different length to diameter (L/D) ratios between 8-15.

Comparison between measured and predicted ultimate capacity of model piles performed in FCV demonstrate a suitable

conformity for similar confinement conditions in the field. Therefore, the FCV can be considered as an appropriate approach

for the investigation of piling geotechnical behavior, and the examination of construction effects.


A. Allahverdi, M. Mahinroosta,
Volume 12, Issue 4 (12-2014)
Abstract

It was found out that the logarithmic models fit the cement–slag blend systems well. In the present study, based on the experimental results, a logarithmic model has been developed to predict the compressive strength of chemically activated high phosphorous slag content cement. Mixes of phosphorous slag (80 wt.%), Portland cement (14 wt.%) and compound chemical activator (6 wt.%) were prepared at different Blaine finenesses using a laboratory ball mill. Compressive strengths of mortar specimens cured in lime-saturated water were measured at different curing times. Mathematical model was prepared in terms of curing time and water-to-cement ratio as independent variables and compressive strength as dependent variable. The comparisons between the model reproductions and the experimentally obtained results confirm the applicability of the presented model.
H. B. Ozmen, M. Inel, S. M. Senel, A. H. Kayhan,
Volume 13, Issue 1 (3-2015)
Abstract

Seismic performance and loss assessment studies for stock of buildings are generally based on representative models due to extremely large number of vulnerable buildings. The main problem is the proper reflection of the building stock characteristics well enough by limited number of representative models. This study aims to provide statistical information of structural parameters of Turkish building stock for proper modeling using a detailed inventory study including 475 low and mid-rise RC building with 40351 columns and 3128 beams for member properties. Thirty-five different parameters of existing low and mid-rise Turkish RC building stock are investigated. An example application is given to express use of given statistical information. The outcomes of the current study and previous studies are compared. The comparison shows that the previous studies have guidance for limited number of parameters while the current study provides considerably wide variety of structural and member parameters for proper modeling.
Mr. Mehdi Goorani, Dr. Amir Hamidi,
Volume 13, Issue 2 (6-2015)
Abstract

This paper presents a model for prediction of the mechanical behavior of sand-gravel mixtures using generalized plasticity and critical state concepts. Proposed model is based on the difference between critical state lines of sand and sand-gravel mixture in e-Lnp' plane. A generalized plasticity model is considered as the base model for sandy soil. Its state parameter, dilation rate and hardening function are modified to involve the effects of gravel particles on the behavior of mixture. Gravel content is considered as a physical parameter for determination of four new added parameters of the model. Verification of the proposed model performed considering four sets of experiments conducted by different researchers on poorly graded sand-gravel mixtures. According to the results, proposed model provides satisfactory qualitative and quantitative predictions of the behavior of sand-gravel mixture. Stress- strain behavior besides volumetric strains in drained condition and induced pore pressure during undrained loading are satisfactory predicted which indicates the possibility of its application in boundary value problems of geotechnical engineering.
F. Dastjerdy, Dr O.r. Barani, Dr F. Kalantary,
Volume 13, Issue 3 (12-2015)
Abstract

In this paper, a finite element model is developed for the fully hydro-mechanical analysis of hydraulic fracturing in partially saturated porous media. The model is derived from the framework of generalized Biot theory. The fracture propagation is governed by a cohesive fracture model. The flow within the fracture zone is modeled by the lubrication equation. The displacement of solid phase, and the pressure of wetting and non-wetting phases are considered as the main unknown parameters. Other variables are incorporated into the model using empirical relationships between saturation, permeability and capillary pressure. Zero-thickness element and conventional bulk element are used for propagating fracture and the surrounding media, respectively. The model is validated with respect to analytical solution of hydraulic fracture propagation problem in saturated media and then the problem is solved in semi-saturated media, considering the wetting and non-wetting pore fluid. 


Omar Al Hattamleh,
Volume 14, Issue 2 (3-2016)
Abstract

ABSTRACT The influence of the sand placement method above geotextile layer on interface shear strength behavior was investigated. Seven different types of woven and non woven geotextile were used with only poorly graded sand. The investigation involved placement of sand layer through inclined horizontal plane with different angles. This step constitutes a fundamental step for assessing soil to be deposited in different plane and therefore with different internal soil fabric. The interface shear strength was evaluated by using direct shear test. Although the investigated soil is uniform poorly graded sand, the influence of the deposit plane was significant especially for nonwoven geotextile. Differences in soil interface shear strength associated with the tested geotextiles samples shows that samples with higher mass per unit area and same opening sizes had the higher interface friction angle regardless the bedding plane. Influence of bedding plane on interface modulus of elasticity which used in most of interface modeling was investigated using Janbu’s formula. It is noted that the use of secant interface modulus of elasticity at 1% strain and at 50% of peak stresses gave a consistent prediction of n and Ku constant appear in Janbu’s formula for all types of geotextile. The above results were reflected in the prediction for interface molded such as Chen and Juran as shown. Therefore, the existing interface modeled is needed to be modified to account for the method that the sand is being placed above the geotextile layer.


Behrooz Mehrzad, Abdolhosein Haddad, Yaser Jafarian,
Volume 14, Issue 2 (3-2016)
Abstract

Currently, there is no reliable design procedure which considers all aspects of liquefaction effects on shallow foundations. There are many light and heavy structures resting on saturated sand with high liquefaction potential in seismic areas. The aim of this experimental and numerical study is to evaluate the performance of two shallow foundations with different contact pressures in liquefaction. The results of the centrifuge experiment of shallow foundations with surcharges of three-story and nine-story buildings on liquefiable sand are presented in detail. Although entire soil profile liquefied, no liquefaction observed under the foundations. There was a clear difference in settlement mechanisms observed beneath the shallow foundation and in the free-field. The heavy foundation fluctuated more strongly compared with the lighter one. The effect of soil permeability and contact pressure on foundation response was investigated during numerical study. The experiment was simulated two dimensionally using a fully coupled nonlinear constitutive model (UBCSAND) implemented in a finite difference program, FLAC-2D. The results show that settlement of foundations increased with the increase of soil permeability. Trends of excess pore water pressure were captured reasonably by the soil model, but the settlement mechanisms were different. The soil model underestimated total liquefaction-induced settlement of shallow foundation, especially for light foundation.


Hanane Dob , Salah Messast, Abdelhamid Mendjel, Marc Boulon, Etienne Flavigny,
Volume 14, Issue 7 (10-2016)
Abstract

Considerable strains appear in the structures during accumulation of the irreversible strains of the subgrade under the effect of the cyclic loads. If the number of cycles is very large, even a small strain after accumulation becomes significant and sometimes harmful. In this study, a simple numerical modeling of the behavior of sand under cyclic loading is proposed. The suggested approach consists, in drained condition, in determining the parameters characterizing the average cyclic path of the soil under the effect of the number of cycles duly characterized and translating the cyclic effect by a volumetric strain cumulated by a variation of the module of the soil. In this study, we are interested in cyclic triaxial compression tests simulated by a finite element calculation. While proposing an analogy between the cyclic pseudo creep and the soft soil creep model (SSCM), on the first hand we propose an equivalence between the cyclic parameters and the parameters of SSCM, and on the other an equivalence time number of cycles will be established. The application of the formulation suggested on a shallow foundation under cyclic loading confirms the good adaptation of the model suggested to this type of problem.


Manoochehr Fathi Moghadam,
Volume 15, Issue 4 (6-2017)
Abstract

Stilling basins and hydraulic jumps are designers’ favorable choice for energy dissipation downstream of spillways and outlets. A properly designed stilling basin can ensure considerable energy dissipation in the short distance of a basin. In this study, experiments have been conducted to evaluate effects of a perforated sill and its position on the length of a favorable B-type hydraulic jump in a stilling basin. Perforated sills with different heights and ratio of openings were placed in different positions of the stilling basin. Tests were carried out for three tail water depths to assess the sensitivity of the jump to tail water. The hydraulic characteristics of the jump were measured and compared with continuous sill-controlled and free hydraulic jumps. Results of the experiments confirmed significant effect of the perforated sill on dissipation of energy and development of the jump in a shorter distance. Results are also presented in the form of mathematical models for estimation of the sill height, sill position, and basin length with the inflow measurable parameters of depth and velocity.


Hyun-Ki Choi,
Volume 15, Issue 4 (6-2017)
Abstract

This study investigated the structural behaviors of reinforced concrete shear walls containing opening and slab. A series of three half-scale shear wall specimens were tested: a solid wall (WS-Solid), a wall with opening and slab (WS-023), and a wall with opening but no slab (WB-0.23). Using the experimental results, the reduction in the load-carrying capacity of the wall due to the loss of cross section was evaluated. Its contribution to the moment resisting capacity of the total system of coupling elements and its structural behavior was also examined. The results of experiments conducted on the WS-0.23 specimen with artificial damage due to installation of the opening, showed that the load-carrying capacity of the wall decreased as a result of the opening. It is apparent that the influence of cutting reinforcing bars and reduction of effective sectional area lead to early first yield of the reinforcing bars before the allowable limit of the drift ratio of the shear walls is reached. This decrease in the load-carrying capacity of the shear wall because of installation of openings is significantly different from the results of previous studies. This is because slabs and the remaining wall function as coupling elements for the shear wall. The contribution of slabs and residual wall to the lateral load resisting system was investigated via an empirical test and finite element analysis. During the experiment, a U-shaped critical section of coupling slab was observed and its effective width and the total length of the critical section examined. The critical section of coupling slab that functions as a coupling element for shear wall varied marginally from the results of previous studies. The results of the analysis conducted show that slabs and residual walls contribute approximately 30% to the lateral load resisting system.


Ali Allahverdi, Mostafa Mahinroosta, Shima Pilehvar,
Volume 15, Issue 5 (7-2017)
Abstract

Compressive strength is as one of the most important properties of concrete and mortar that its measurement may be necessary at both early and later ages. Prediction of compressive strength by a proper model is a fast and cost-effective way for evaluating cement quality under various curing conditions. In this paper, a logarithmic model based on the results of an experimental work conducted to investigate the effects of curing time and temperature on the compressive strength development of chemically activated high phosphorous slag content cement has been presented. This model is in terms of curing time and temperature as independent variables and compressive strength as dependent variable. For this purpose, mortar specimens were prepared from 80 wt.% phosphorous slag, 14 wt.% Portland cement, and 6 wt.% compound chemical activator at Blaine fineness of 303 m2/kg. The specimens were cured in lime-saturated water under temperatures of 25, 45, 65, 85 and 100 ºC in oven. The model has two adjustable parameters for various curing times and temperatures. Modeling has been done by applying dimensionless insight. The proposed model can efficiently predict the compressive strength of this type of high phosphorous slag cement with an average relative error of less than 4%.


Ahmad Soltanzadeh, Iraj Mohammadfam, Abbas Moghim Beygi, Reza Ghiasvand,
Volume 15, Issue 7 (10-2017)
Abstract

Construction industries are the most dangerous worksites with high risk of occupational accident and bodily injuries, which ranges from mild to very severe cases. The aim of this study was to explore the causal factors of accident severity rate (ASR), in 13 of the biggest Iranian construction industries. In this analytical cross-sectional study, the data of registered accidents from 2009 until 2013 were obtained from an official database. Data of HSE risk management systems and HSE training were also gathered from comprehensive accident investigation reports. Data analysis and regression modeling were done using SPSS statistical software (version 22). The mean and SD of ASR of studied construction worksites was 257.52±1098.95. The results show that the system associated with HSE and HSE risk management established only 41.8 and 18.4%, respectively. The results of multiple linear regression indicated that some individual and organizational factors (IOFs), HSE training factors (HTFs), and Risk Management System factors (RMSFs) were significantly associated with ASR (p<0.05). The study revealed the causal factors of ASR. Hence, these findings can be applied in the design and implementation of a comprehensive HSE risk management system to reduce ASR.



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