International Journal of Civil Engineering
Volume:14 Issue: 3, 2016

Various methods have been applied to the construction crew productivity problem. This paper introduces the use of two novel artificial intelligent methods; which are self organizing maps (SOM) and artificial bee colony (ABC). It first presents the results of prediction performances of these two methods and also focuses on the visualization ability of SOM through the presentation of two dimensional maps produced for the current problem. The prediction performances are evaluated by comparing MAPE, MAE and MSE values obtained during the sevenfold cross validation.

This paper presents a novel approach to solve the double-track railway rescheduling problem, when an incident occurs into one of the block sections of the railway. The approach restricts the effects of an incident to a specific time, based on which the trains are divided into rescheduled and unchanged ones, so that the latter retain their original time-table after the incident. The main contribution of this approach is the simultaneous consideration of three rescheduling policies: cancelling, delaying and re-ordering. A mixed-integer optimization model is developed to find optimal conflict-free time-table compatible with the proposed approach. The objective function minimizes two cost parts: the cost of deviation from the primary time-table and the cost of train cancellation. The model is solved by CPLEX 11 software which automatically generates the optimal solution of a problem. Also, a meta-heuristic solution method based on simulated annealing algorithm is proposed for tackling the large-scale problems. The results of an experimental analysis on two double-track railways of the Iranian network show an appropriate capability of the model and solution method for handling the simultaneous train rescheduling. The results indicate that the proposed solution method can provide good solutions in much shorter time, compared with the time taken to solve the mathematical model by CPLEX software.

Comprehensive computational analysis was made for modelling the integrated hydrologic–hydraulics characteristics of varied unsteady flow in hydraulic structures as part of water engineering practices and river basin management. Several numerical skills, linear, non-linear, implicit, explicit methods were developed and tested with existing river analysis software of Danish Hydraulic Institute (DHI) and Hydrologic Engineering Centre (HEC) series models. Coupled hydrological and hydraulics analysis of storming run-off flows in broad waterway boundaries including flood plains of compound sections was performed. Application of models was encouraging, the complex water conveyance systems that transported lateral flows in natural rivers were modelled satisfactorily. Storming flow events in real rivers were coded and compared through different numeral techniques such as method of characteristics, Mac-Cormack, diffusive numeral model and Preissmann fully implicit model. Predicted results were close to observed values verified and confirmed the hand-written codes and programs in MATLAB environment. Enhanced modelling skills were justified by (HEC) series and Mike series computer software. Merits of this research were seen based on: numerical accuracy, consistency, stability and convergence results to observed targets.

This paper presents a cooperative-bargaining game model for quantitative risk allocation that extends the previous existing system dynamics (SD) based model. The proposed model accounts for both the client and the contractor costs to perform the quantitative risk allocation process. In this research, the behavior of contracting parties in the quantitative risk allocation process is modeled as the players’ behavior in a game. The cooperative game forms at a risk allocation percentage at which the summation of the client and the contractor costs are minimized. A bargaining process is then performed to share the benefit of a decrease in the contractor costs between the client and the contractor. To evaluate the performance of the proposed model, it has been employed in a pipeline project. The quantitative risk allocation is performed for the inflation as one of the most important identified risks. It is shown that using the proposed cooperative-bargaining game model, the percentage of risk allocated to the client is determined to be 100. Hence, the client and the contractor costs are decreased by 3.1 and 3.7 % in comparison to the previous SD-based risk allocation approach, respectively.

The contribution of concrete to an inelastic deformation capacity and shear strength of reinforced concrete (RC) columns failing in shear has been investigated extensively by various researchers. Although RC members are designed to have shear strengths much greater than their flexural strengths to ensure flexural failure according to the current codes, shear degradation of RC columns failing in flexure has not been studied widely. The aim of this study is to investigate the contribution of concrete to shear strength of RC columns using finite element analyses (FEA). The results of FEA are compared with the results of experimental studies selected from literature, and it is observed that the lateral load–deflection curves of analyzed columns are compatible with the experimental results. Twenty six RC columns were analyzed under monotonically increasing loads to determine the concrete contribution to the shear strength. The results of analyses indicate that increasing the ratio of shear to flexural strength reduces the concrete contribution to the shear strength of the columns.

With the ongoing developments in numerical analysis methods, it is possible to model the soil–foundation–structure interaction and nonlinear load-deformation behavior of soils in three-dimensional calculations. In light of these developments, the calculations of mat foundations can be made more realistically and economically by using advanced softwares, which take into account the interactions of these three components than the conventional methods. The aim of this paper is to present the effect of superstructure loading types on the analysis of mat foundations by using three-dimensional finite element analysis results. Thirty-six different models have been established to examine these effects on the internal forces and settlement behavior. The data of a three-storey existing building has been used and superstructure loads have been modeled in different ways such as uniformly distributed loads, column loads and by modeling all buildings. The building has been modeled with a mat foundation having a thickness of 50, 75 and 100 in separate models. The mat and superstructure elements have been modeled either with 2D plate elements or 3D volume elements in different models. The “Mohr–Coulomb” material model has been used and soil properties have been represented as “normally loaded” and “overconsolidated”. Results for total and differential settlements and internal forces have been presented in figures and graphs. An important finding is the place where the maximum displacement occurs. It is very different when the load is transmitted by modeling the whole structure and it causes to have different internal forces and different placement of reinforcement. Another finding is that the biggest decreases in differential settlements are seen in column and building loading when the soil properties improved, while this effect remains very small in distributed loading. For bending moments, the biggest difference in comparison to the loading types is that the maximum moments are calculated in different places independent of the location of shear walls, when the load is simulated as a uniformly distributed load. It has been found that the superstructure loading type affects the settlement pattern and internal forces, so this effect must be taken into account.