International Journal of Civil Engineering
Volume:14 Issue: 6, 2016

The geometric design of a road based on consistency implies that this should not violate driver expectations. Although there are different methods for estimating consistency, the most used have been those based on the operating speed of vehicles. This is due to its relationship with accidents. Road alignments which cause marked differences in vehicle speeds favour a greater accident rate. In this research, local approaches to evaluate the consistency of the alignments (tangents, curves) versus global approaches to evaluate an entire stretch of road have been analyzed. Different models have been used to estimate an operating speed of vehicles. The study has focused from a practical point of view using two applications for the evaluation of consistency of a stretch of road. The results show the influence of the choice of the speed model in the level of consistency. In addition, practical issues about how some variables, such as desired speed, posted speed, and design speed, can influence the results that are presented.

In the current study, the dynamic mechanical behaviour of a masonry cupola composed of non-convex discrete elements is investigated. This cupola is designed in innovative and modern ways and was recently constructed with stone blocks in the south of France. The necessity of applying an accurate numerical modelling method being able to take into account the real geometry of each non-convex block is also presented and discussed. The stability state of this masonry structure, by considering the different levels of seismic loads is studied. In addition, the effects of changes in the contact condition between blocks, or the blocks and the structure foundation, are comprehensively investigated.

In this paper, using the eigenvalues and eigenvectors of symmetric block diagonal matrices with infinite dimension and numerical method of finite difference, a closed-form solution for exact solution of Laplace equation is presented. The method of this paper has applications in different states of boundary conditions like Neumann, Dirichlet, and other mixed boundary conditions. Using the method of this paper, a mathematical model for the exact solution of the Poisson equation is derived. Since these equations have many applications in engineering problems, in each part of this paper, examples, like water seepage problem through the soil and torsion of prismatic bars, are presented. Finally, a method is provided for torsion problem of prismatic bars with non-circular and non-rectangular cross-sections utilizing conformal mapping.

In this article, general procedures for vulnerability assessment and retrofitting of a generic seismically designed bridge are outlined and the bridge’s damage criteria for blast resistance are explained. The generic concrete bridge is modeled and analyzed with the finite element technique implemented in ANSYS LS-DYNA environment and explosion threats are categorized into three main levels. Uncoupled dynamic technique is adopted to apply the blast loads on the bridge structure; damage and performance levels are resulted based on quantitatively verified damage mechanisms for the bridge members. The results show that, among different loading scenarios, the explosions that happen under deck are more critical compared to blasts initiating from over deck sources. Furthermore, two retrofitting (1) concrete filled steel tube (CFST) and (2) concrete jacket are applied on the bridge columns. The program AUTODYN is used with coupled dynamic analysis of a column to compare the effectiveness of each method. Afterward, more efficient method for a column is applied to the whole bridge and its efficiency is revaluated. It is shown that CFST can decrease concrete spall, scabbing, rotation, displacements and shear forces more than the concrete jacket. Considering the proposed damage and performance levels, the bridge retrofitted with CFST reacts with lower damage level and higher performance level to blast loads.

Replacement of existing unreinforced masonry (URM) walls, commonly used as a non-structural member in apartments, with new reinforced concrete (RC) components has been used as a reliable method when remodeling is carried out. However, special care needs to be taken when URM walls are removed not to waste construction time and materials. Therefore, retrofitting existing URM walls can be deemed a better solution rather than replacing URM walls with RC ones. Using shotcrete is one of retrofitting techniques of URM walls. However, using normal shotcrete cannot improve adequate ductility and may cause brittle failure at a wall frame or slab connection. Therefore, new materials, such as engineered cementitious composite (ECC) and ultra-high performance concrete (UHPC) have emerged to resolve the problem of normal shotcrete by increasing ductility and toughness of retrofitting materials. In this study, sprayed ECC was used to increase both strength and ductility of existing URM walls. The results of two retrofitted URM walls under lateral quasi-static loading were compared to non-retrofitted one. One strengthened wall, retrofitted masonry wall (RTM)-ECC, was just sprayed and anchored to a wall base. Another strengthened wall, RTM-ECC-WM, was the same as RTM-ECC except for addition of wire mesh. The retrofitted specimens showed significant increase of strength, ductility, and energy dissipation capacity in comparison with the control one. In addition, RTM-ECC-WM indicated higher strength degradation due to the load transferring effect of wire mesh than RTM-ECC.

Efflorescence formation is an important soundness issue to be considered with alkali-activated cements. In this study, the impact of activator type on the efflorescence formation severity and methods of efflorescence reduction in alkali-activated phosphorus slag cement are investigated. Different alkaline activators including NaOH, KOH and liquid sodium silicate of different silica modules (Ms = SiO2/Na2O) were used for alkali-activation of phosphorus slag. Additions of high alumina cements (Secar 71 and 80) and application of hydrothermal curing condition at 85 °C for 7 h with different pre-curing times (1, 3 and 7 days) in humid environment (relative humidity of 95 %) and 25 °C were used for efflorescence control in alkali-activated phosphorus slag cement. Sodium containing activators resulted in more severe efflorescence formation compared with those of potassium containing activators. Also presence of liquid sodium silicate intensified efflorescence formation. Based on the results obtained, application of an optimum pre-curing stage in humid environment before hydrothermal curing regime stabilizes the cement matrix and improves the effectiveness of hydrothermal conditions.