Sharif Digital Repository

v.1. Structural engineering and earthquake engineering.-- v.2. Geotechnical engineering.-- v.3. Transportation, civil engineering materials, construction management.-- v.4. Water resources and environmental engineering, surveying and mapping  

A rectangular labyrinth weir has a very good flood release capacity as well as strong economical and structural advantages. In this study, combined analytical and experimental investigations were undertaken for a rectangular labyrinth weir. The analytical model is based on the synthesis of general weir equations and spatially varied flow dynamic equations. A comprehensive set of experiments led to characterisation of the flow behaviour for low and high heads over the weir and indicated the influences of weir geometry on the release capacity. The results show that this type of weir represents an effective weir alternative and could be five times more efficient than a corresponding traditional... 

Daily development in civil engineering arena and the importance of economical aspects in the design of structures have motivated the engineers to shift their approaches from designing upon strength to designing upon performance. This is of more importance regarding the forces induced by earthquakes which have unpredicted and random nature. However, it is not possible to design or assess exactly the structural performance against strong ground motion using analytical methods which are applied for static loads and therefore precise dynamic analysis methods are needed. Despite significant progress in the analytical methods and engineering software, using nonlinear time history analysis is very... 

Labyrinth side weirs provide a potentially effective way to shorten the length of a channel opening with the desired water height, but the discharge coefficient needs to be found experimentally. Experiments were carried out for triangular labyrinth side weirs with one and two cycles in order to obtain the discharge coefficient. The test variables included channel opening, head angle, number of cycles, weir height, upstream water depth and discharge in a subcritical situation. The resultsshow that the discharge coefficient ratio for a triangular labyrinth to a conventional side weir could rise to more than 2 with the same flow and geometric conditions. Relationships for the De Marchi... 

Asphaltic concrete has been used as waterproofing core in embankment dams, since 1948. In this application, the asphaltic core is surrounded by granular filter materials. The interaction of the asphaltic concrete and the granular materials has not been sufficiently investigated. In this paper the mechanical behavior of the interface between a natural smooth sand filter and asphaltic concrete at different levels of normal stresses and a constant shear strain rate has been studied. Small scale direct shear test has been conducted in this study, in which the shear surface is considered as the interface. Asphalt concrete specimens used in the shear test were cut in square shape (10×10×2.5 cm)... 

Organoclay modification is receiving attention as a nano-modifier for asphalt binders. Nanoparticles are able to effectively mend the damaged sites of the nanocomposite without external intervention. Particle-polymer interaction results in packing particles into developed cracks, thereby mending the cracks during patch formation. This study investigates the rheological properties of organoclay modified binders with a focus on their fatigue properties. To this end, the dissipated energy concept, the ratio of dissipated energy change and plateau value (PV) energy were examined during fatigue tests using a dynamic shear rheometer. The effects of strain level, frequency and temperature on unaged... 

Iran is engaged in a long-term program to improve and strengthen its position among producers of petroleum in the world. In this regard, many projects are planned and executed in different fields related to oil and gas industry. Prior to investment in new projects, it is essential to understand and manage major corporate risks and their related consequences. Due to nature of petroleum industry, Health, Safety and Environmental (HSE) issues are associated with such projects and have always been matters of concern. This paper directs readers towards the integrated HSE approach from concept to affect project construction phase. The process of oil production includes exploration, extraction and... 

This paper investigates the deflection and static pull-in of microbridges based on the modified couple stress theory, a non-classic continuum theory able to predict the size effects for structures in micron and sub-micron scales. The beam is modeled using EulerBernoulli beam theory and the nonlinearities caused by mid-plane stretching have been considered. It is shown that modified couple stress theory predicts size dependent normalized deflection and pull-in voltage for microbeams while according to classical theory the normalized behavior of microbeams is independent of the size of the beam. According to results, when the thickness of the beam is in order of length scale of the beam... 

The earned value management (EVM) is a tool commonly used to monitor both cost and schedule performance, based on the current status of a project. However, EVM does not consider the variation rate of project performance during project execution phase, which may oscillate, causing unexpected time and cost overruns or even project failure at the end. In this research, a methodology for monitoring project time and cost adverse variation rate, by the use of statistical process control (SPC), is introduced. This methodology improves the previous investigations in this field by considering overall required conditions and circumstances. Process capability indices of SPC, as a very powerful tool for... 

HSE management is one of the key topics in project management that plays a significant role in indication of success and soundness of projects. According to the official reports and statistics, construction industry has annually incurred a great deal of expenses and losses due to neglecting the role of HSE issues in the projects worldwide. Since many challenges and problems related to HSE faced Iranian civil engineers and construction managers, recently the HSE have been regarded as a highly critical issue in Iran. Observations show that many Iranian managers and engineers, in their daily activities, have the tendency to ignore the HSE related rules. The aim of this research is to evaluate... 

One of the most conventional and energy efficient methods to improve the engineering properties of concrete is the utilization of waste materials and by-products. Among agricultural wastes, rice husk ash (RHA) has exhibited the greatest potential to enhance the characteristics of cement mixtures. However, the investigations on the properties and performance of RHA are slim compared to its potential advantages and few systematic studies can be found in the literature regarding parameters influencing the chemo-physical and microstructural characteristics of RHA along with its performance in cement mixtures. In this study, the effect of retention time of rice husk is systematically... 

In Endurance Time (ET) method gradually intensifying acceleration functions are created in a manner that the linear and nonlinear response spectra of them, while being proportional to average of real earthquakes spectra, intensifies in a uniform manner with time. These functions are used as input functions for nonlinear time history analysis of structures and performance of structures is assessed based on the maximum time duration that they can meet the specified performance objectives. In this paper, application of the ET method in nonlinear seismic analysis of structures has been investigated. Numerical procedures and optimization techniques that are used for the production of acceleration... 

Purpose - The purpose of this paper is to analyze a squared lattice cylindrical shell under compressive axial load and to optimize the geometric parameters to achieve the maximum buckling load. Also a comparison between buckling loads of a squared lattice cylinder and a solid hollow cylinder with equal weight, length and outer diameter is performed to reveal the superior performance of the squared lattice cylindrical shells. Design/methodology/ approach - A cylindrical lattice shell includes circumferential and longitudinal rods with geometric parameters such as crosssection areas of the rods, distances and angles between them. In this study, the governing differential equation for buckling... 

Development of technology has made possible the invention of innovative and modern methods to partially solve the problems caused by traffic congestion through decreasing the need for physical transportation; one such method being telecommuting. Although, research has been conducted to model employees' and employers' attitude towards telecommuting at micro levels, few predictions have been reported regarding its aggregate demand at the macro level of a city, generally because of the complexity and multi-dimensionality of the subject. In this paper, an approach for the estimation of potential aggregate telecommuting demand is proposed to partly fill the gap in the literature; and applied for... 

The final outcome of promotion and recruitment processes in universities should be conventional and plausible by the members of the relevant scientific community, to affirm that the processes have been competitive and fair. The objective of this opinion letter is to make a plea for the importance of the post-auditing and quantitative assessment of the selection criteria. It is shown that for an example case the outcome of the post-audit does not look reasonable from an external point of view, at least regarding the research competency  

Investigation of the dynamic characteristics of an existing structure system based on field tests is of practical significance, since it can be employed in the field of examining construction quality, validating or improving analytical finite element structural models, or conducting damage assessment. The main purpose of this study is to investigate the dynamic characteristics of dams using the seismic response data. Whereas, in the process of frequency domain identification of dam properties, frequency response function (FRF) plays the most important role, evaluating the corresponding parameters with better accuracy has always been desirable. Therefore, a comparison was made between some... 

Maintaining of concrete gravity dams in good conditions as one of the important infrastructures is significant concern for dam owners. These dams should able to continue their function after a disaster such as earthquake. But most of them are aged dams with some located near faults. Indeed, there are some concerns regarding the performance of these dams under the effect of seismic loads. In recent years some criteria about linear performance of these dams have been developed. But the same cannot be said about nonlinear behavior of these dams, which seem to lack well-developed criteria. In this paper we shall try to illustrate seismic fragility curves for concrete gravity dams by using... 

The history of the building structures damaged during previous earthquakes reveal that one of the causes of these damages was the existence of some sort of irregularity in the structure of these buildings. In this work, the effects of irregularities due to the split in the levels of various parts of some 2D steel structures (Split Level) on their seismic behaviour are studied. The studied frames consist of five-, ten- and fifteen-storey frames, each with 0, 30, 60, 90, 120, and 150 cm split between the storey levels of the two parts (sides) of the building. The modal analysis of these frames showed that a high percentage of their base shear is transferred to the foundation through the... 

Purpose - This paper aims to address the capability of reliability-centered maintenance (RCM), which is a preventive maintenance design tool. Design/methodology/approach - A model named Plant Function Deployment (PFD) is developed, in which the methodology of quality function deployment (QFD) is added to RCM to improve RCM capability in preserving the functions of the plants. Findings - The objective of preserving the plant functions with least resources, in RCM, is attained more efficiently if the methodology of QFD is added to RCM. Practical implications - PFD is a model for designing a preventive maintenance program which uses RCM and QFD methodologies. PFD organizes all the important... 

In order to evaluate the seismic behavior of confined masonry buildings, based on Iranian seismic code design, a single storey full-scale unreinforced confined brick masonry building has been constructed on the shaking table facility at the Earthquake Engineering Research Center (EERC) of Sharif University of Technology. The 4 by 4 meter model consists of four brick masonry walls confined with reinforced mortar tie-columns and steel bond beams, with a traditional jack-arch roof system. Three of the wall panels contained openings of different sizes and geometries. The model was subjected to the scaled earthquake records of Bam, Tabas and El Centro, as well as a harmonic acceleration with...