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Well-known seismic design codes have offered an alternative equivalent static procedure for practical purposes instead of verifying design trials with complicated step-y-step dynamic analyses. Such a pattern of base-shear distribution over the building height will enforce its special stiffness and strength distribution which is not necessarily best suited for seismic design. The present study, utilizes a hybrid optimization procedure to seek for the best stiffness distribution in moment-resistant building frames. Both continuous loading pattern and discrete sizing variables are treated as optimization design variables. The continuous part is sampled by Harmony Search algorithm while a variant of Ant Colony Optimization is utilized for the discrete part. Further search intensification is provided by Branch and Bound technique. In order to verify the design candidates, static, modal and time-history analyses are applied regarding the code-specific design spectra. Treating a number of building moment-frame examples, such a hyper optimization resulted in new lateral loading patterns different from that used in common code practice. It was verified that designing the moment frames due to the proposed loading pattern can result in more uniform story drifts. In addition, locations of the first failure of columns were transmitted to the upper/less-critical stories of the frame. This achievement is important to avoid progressive collapse under earthquake excitation.

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This paper presents a simple solution based on the limit equilibrium of sliding soil wedge of reinforced backfill subjected to the horizontal acceleration in the framework of the pseudo-static method. In particular, contrary to most studies on the reinforced retaining wall, the solution proposed in this study, takes into account the effect of the uniform surcharge on the reinforced backfill soil and of its distance from the face of the wall. The results are investigated in dimensionless form of the maximum reinforcement required strength (Kmax), the dimension of the sliding wedge (Lc/H), and the factor of safety (FS). Compared to the reinforced backfill without surcharge, the presence of surcharge over the reinforced backfill and of its distance from the top of the backfill have significant effects on the stability of the system. For a fixed surcharge, a minimum distance of surcharge exists for which the presence of the surcharge does not affect the solution and the failure mechanism is that corresponding to the case of system with no surcharge. A detailed design example is included to illustrate usage of proposed procedures. Comparisons of the present results with available results show a favorable agreement.

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The previous studies show that a high percentage of traffic accidents take place in two-lane rural highways and most of which happen at horizontal curves. Meanwhile the horizontal alignment is often subject to hard topographic conditions where because of economic aspects designers are forced to design horizontal curves at grades. Vertical angle of longitudinal slope reduces the normal force of vehicle on road and friction force in tire-pavement surface will decrease. This leads to a lack of sufficient driver control over the vehicle especially if the curve with small radius is located at downgrade. In this paper, the suitability of operating speed and lateral friction coefficient as geometric design criteria for horizontal curves in downgrades are studied with regard to traffic safety and vehicle stability. The investigation of speed reduction of the vehicles running on a horizontal curve at downgrade as a response of driver behavior and the use of friction ellipse theory give the available friction coefficient. Whereas the dynamic analysis of forces applied on the vehicle in curve which is located at downgrade if combined with operating speed results in the required coefficient of lateral friction. Finally, a comparison of these two parameters based on safety evaluation criteria gives an estimation of actual safety level in designing horizontal curve at downgrades with regard to AASHTO’s data in horizontal curve design.

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Limitations in the design method used for the support systems of urban buildings make them vulnerable to damage by adjacent excavations. This paper examines a traditional system used to support excavation sites and adjacent buildings in which inclined struts are connected to the wall or foundation of the adjacent building. This method can be considered to be a type of shoring or underpinning. The performance of buildings and the criteria for deformation control during excavation are introduced. Next, a 2D finite element analysis is presented in which an excavation is modeled considering the parameters from the adjacent building and the inclined struts. The numerical model is capable of simulating the overall excavation and installation of the support system. The soil is modeled using an elastic perfectly-plastic constitutive relation based on the Mohr-Coulomb criterion. The finite element model is validated using Rankine earth pressure and in situ data was measured during an excavation. The effect of different variables on performance and acceptable limits for the inclined strut are discussed. The model used for the parametric study shows the influence of the characteristics of the adjacent building, soil parameters, geometry of excavation, type of excavation and effect of strut installation. It was found that one type of strut arrangement produced the best possible result. The results can be used as a primary approximation of small-to-medium depth excavations in which struts are used to reduce the deflections.

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The main aim of this paper is to find the optimum shape of arch dams subjected to multiple natural frequency constraints by using an efficient methodology. The optimization is carried out by charged system search algorithm and its enhanced version. Computing the natural frequencies by Finite Element Analysis (FEA) during the optimization process is time consuming. In order to reduce the computational burden, Back Propagation (BP) neural network is trained and utilized to predict the arch dam natural frequencies. It is demonstrated that the optimum design obtained by the Enhanced Charged System Search using the BP network is the best compared with the results of other algorithms. The numerical results show the computational advantageous of the proposed methodology.

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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 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 are presented.

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Observations and investigations have proved that using traditional fire curves such as stand-ard fire curves and natural fire curves should be limited to small/medium compartments. In addition, when using the traditional fire curves, a uniform temperature is assumed throughout the compartment. However, for large open compartments, assuming uniform temperature is not compatible with real fires. To overcome this limitation, a non-uniform fire method named as travelling fire is employed as an alternative. A study is performed here on a seismic-damaged large plan 3-story reinforced concrete structure designed to meet the life safety level of performance when exposed to a travelling fire. To draw a comparison, the structural fire analysis is also performed using the traditional methods. The results show a notable difference – while the fire resistance based on the travelling fire is around 91 minutes, it is around 140 minutes when based on a uniform temperature. This shows that the structure studied is more susceptible to failure when subjected to the non-uniform fire than the uniform fire.

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In this study, the usage of the Level of Service (LOS) concept, which was developed specifically for pedestrian satisfaction and safety, was critically analyzed. The focuses of this investigation were the Fruin and Highway Capacity Manual (HCM) LOS values, which were evaluated and compared in terms of their anthropometric dimensions. In this paper, new LOS values are proposed on the basis of the critical evaluation of the HCM and Fruin LOS values revealing the inconsistencies between the LOS values and the analysis. The importance of emptiness area in calculating human comfort and satisfaction in terms of the anthropometric dimensions and LOS value is also discussed. A software program called Laborer Image Analysis Software (LIAS) was developed to evaluate and compare the impacts of different body dimensions on the LOS values and on the space requirements for pedestrians. LIAS is presented as a facilitation tool for calculating more concise and effective emptiness areas and LOS values. The comfort area concept is also presented and discussed. This discussion is used to reveal the contrasts and inconsistencies in the existing usage of the LOS concept and to highlight the importance of the emptiness area approach. The paper presents a different perspective and discussion on the existing utilization of LOS levels, particularly for pedestrians in different structures. The research contributes to the LOS analysis discussion in terms of the anthropometric scale according to changing user profiles and develops facilitator(s) for analyzing and applying amendments to pedestrian needs, which can be used in transportation buildings.

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Based on the methodology of “Understanding by Design”, UbD, the course “Design of Hydraulic Structures” was developed and implemented. A series of learning experiences, with emphasis on hydraulics and hydrology, for civil engineering undergraduate students is presented that encourages the development of high technical and scientific competence, communication skills oral and in written, the ability for teamwork and the capability to learn. The experiences were designed, using the above methodology, based on learning that is desired. Once taught the course, the results obtained were compared based on the planned framework (expectations), the characterization of the student population, the course products as well as the activities, according to the students, considered relevant in the learning process.

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Engineering design usually requires considering multiple variances in a design and integrating them appropriately in order to achieve the most desirable alternative. This consideration takes particular importance in the constructional projects of civil engineering. However, frequently, the structural designer’s considerations in civil engineering teams contrast the stylish and creative novelties of architectures. Then, we should take up new methodologies to yield appropriate alternatives which meet artistic aspects of design and simultaneously satisfy the structural designer’s demands. Consequently, the process of design should incorporate the multi-fold aspects of engineer’s requirements and their personal preference. So, in this study, we preset a systematic approach, so-called desirability based design, to perform a directed multi-objective optimal design considering various aspects of a design, based on soft-computing methods. Fuzzy logic integrated with genetic algorithm is employed to build a decision-making fuzzy system based on expert knowledge. It will be employed to conduct the designing process. Illustrative examples show practicality and efficiency of the presented methodology in structural design of several space structures.

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From practical point of view, optimum design of structures under time variable loadings faces many challenges. Issues such as time-dependent behavior of constraints and the computational costs of the gradients could be mentioned. In order to prevent such difficulties, in this paper, response spectrum method has been utilized instead of applying direct time history method. Additionally, seismic design of structures is defined as a design for a specific response spectra not for an individual acceleration time history. Furthermore, here, in order to guarantee the global optimal designs, the obtained results from gradient-based method are compared with those from the discrete optimization technique (Genetic algorithm). As well, the P-Delta effects are considered in a seismic analysis. In addition, many practical constraints according to the Iranian national building code (NBC) are included in the optimization problem. The developed MATLAB based computer program is utilized to solve the numerical examples of low, intermediate and relatively high-rise braced and un-braced steel frames.

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For years, coupling shear walls have been used in  the mid to high-rise buildings as a part of lateral load- resisting system mostly, because of their ability to control the displacement of structures, Recently by changing the design codes from strength based design to performance based  design, nonlinear behavior of coupled walls became important for practical engineers, so that many researchers  are looking for ways to improve and also predict the behavior of coupled walls under severe earthquakes. This paper  presents  the results of   linear,  nonlinear static ( pushover)  and  nonlinear inelastic time-history analysis  of a 10-story  two- dimensional coupling shear wall (CSW) which is perforated with 3 different patterns which are taken from considering  the S22 stress of shell elements used for modeling shear walls,  nonlinear static analysis results confirm that perforation can increase the response modification  factor of coupled walls up to 33 percent and also the results of  linear analysis and design indicate that perforation can reduce the amount of reinforcement of coupling beams and other frame's  structural components. Also results of nonlinear inelastic time history  analysis confirm that by using perforation patterns the base shear- roof displacement hysteretic response get better and the  systems with perforation patterns can absorb more energy under severe earthquakes.

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Minimum reinforcement ratios provided in the standards are remaining at very low levels especially at large systems subject to the effects of earthquake. Thus, arranging the reinforcement ratios intended for preliminary design can provide significant ease and safety in project design phase, and speed and simplicity in the project control phase. Moreover, a more realistic limitation becomes ensured compared to general minimum reinforcement ratios given in the standards. System characteristics which may affect the reinforcement ratios can be specified by general and simple parameters. As the result of many extensive studies, expressions for reinforcement ratios intended for preliminary design which will cover systems having different parameters can be composed. Today, thanks to the development levels of finite elements programs which can perform reinforced concrete modeling, meeting this requirement is much more possible compared to the past. Structure of parameters should neither be very special nor very general. Otherwise, reinforcement ratios intended for preliminary design will either be valid for a single system or they will remain at very low limits such as the minimum reinforcement ratios given in the standards. For this reason, in this study it was tried to follow a route in between these two extreme conditions. Today, it is possible to perform many studies on the systems having different and comprehensive inclusive parameters and to determine practical ratios which will constitute a recommendation for the project designs. For this purpose, an eight storey reinforced concrete system with single spacing whose shear wall cross-section is 25x250cm, column cross-section is 25x30cm, and beam cross-section is 25x50cm was addressed, and its non-linear planary analyses under static earthquake loads were performed through the ANSYS finite elements program for 13 different reinforcement case. The reinforcement ratios to be recommended for the addresses system and similar systems were tried to be revealed. The examined system was arranged as to get the most critical and extreme values for many parameters which can be considered, but it was tried for the reinforcement ratios to be recommended to be valid not only for this system but also for the general system network having similar properties to this system. In the future researches, expressions of general and inclusive preliminary design reinforcement ratios can be obtained as per the results of many studies to be made on systems having different parameters.