با افزایش میزان جمعیت، استفاده روزافزون منابع طبیعی برای تولید مواد مناسب برای ساخت و ساز مانند آجر، سیمان و میله‌های مستحکم وجود دارد. این امر به طور تصاعدی قیمت انان را افزایش داده و همچنین آلوده کردن محیط با تولید مقدار زیادی از گازهای گلخانه‌ای را به همراه داشته است. بنابراین نیاز به ارائه زیرساخت ارزان و بادوام وجود دارد. در این تحقیق هدف ارزیابی استفاده از نی های مازندران که به وفور در زمین های کشاورزی و شالیزارها یافت می شود، در صنعت ساختمان بود که بدون استفاده درست و موثر از بین برده می شود. بدین منظور ابتدا چند طرح اختلاط برای جایگزینی شن در بتن های معمولی با سنگدانه های درشت حاصل از نی ساخته شد و میزان مقاومت فشاری طرح ها در سنین 7، 28و 90 روز ارزیابی شد. با جایگزینی کامل شن با نی مازندران نزدیک به 60 درصد افت مقاومت فشاری رخ داده است. هرچند این افت قابل ملاحظه است اما منجر به تشکیل یک بتن با مقاومت 7 روزه نزدیک به 10 مگاپاسکال شده است. در ادامه با ساخت دو پنل دیواری با ردیف های نی مازندران در دو حالت بدون مش فولادی و با مش فولادی در دستور کار قرار گرفت. برای ارزیابی مقاومت فشاری این دو پنل آزمایش چکش اشمیت برای هر دو پنل در سن 28 و 90 روز انجام شد. نتایج بدست آمده استفاده از سنگدانه های نی در بتن ها مقاومت قابل قبولی برای ساخت قطعات پیش ساخته غیر سازه ای نشان داده است. همچنین استفاده از نی به جای میلگرد ها در پنل های دیواری رفتار مشابهی با پنل دارای میلگرد داشته و عملکرد مناسبی از خود نشان داده است و همچنین پنل های دیواری ساخته شده با نی نسبت به دیوار چینی عادی با بلوک حدود 15درصد هزینه کمتری دارد.

Ever-increasing demands of the modern world and the growth of industry requirements toward more accurate analyses have made the engineering community develop the first fundamental step and meet the needs by extending the previous prevalent linear methods into nonlinear areas. In this regard, the improvement of linear modes as one of the most pervasive and widespread analytical methods opens a new window to analyses with more closeness to reality. In this paper, after the deep identification of Nonlinear Normal Modes, an approach is proposed to analyze the multi-degree-of-freedom structures with nonlinear material under undamped free vibration. Afterward, through an in-depth investigation of the calculation methods, a novel algorithm for identifying Nonlinear Normal Modes was proposed, and by expanding this algorithm to the existing invariable motion equation used in free vibration analysis, the possibility of the extraction of all Nonlinear Normal Modes has emerged. After that, to investigate the functionality of the proposed approach, the Finite Elements Method-based Model of a 2-story steel structure was developed and, after verification, it was used to form the invariable differential equations. Finally, after verifying the Independent Periodic Method, pseudo-continuous masses of Nonlinear Normal Modes and Frequency-Energy curves of the mentioned structure were calculated. It is worth noting that the independency of resulted response to previous points, the possibility of capturing Nonlinear Normal Modes with different frequencies in each degree-of-freedom, the potential of capturing all internal resonances, the expendability of Finite Elements Model to a set of invariable motion equations, and considering material nonlinearity are among achievements of the current paper.

Given the increasing importance of time, cost, and resource management, organizations are pushing for a knowledge base consisting of all the knowledge acquired during a project, and with the prior knowledge being put in place to maximize productivity. The purpose of this research is to investigate the effect of knowledge management on the delays of road construction projects in project-oriented organizations. The present study, after explaining the concept of knowledge management and identifying the causes of delays in road construction projects, examines the components of knowledge management and the impact of each of them on reducing the time latency of road construction projects through a questionnaire study method. Then, one of the sub-criteria of delay factors and its effectiveness from knowledge management was investigated. For this purpose, a statistical population consisting of active employers, consultants and contractors in the road construction sector of Southern Khorasan province was considered and parametric tests were used for inferential analysis. Findings show that there is a significant positive two-way relationship between knowledge management and reducing project time latency. This means that the more knowledge management is used in road construction projects, the greater reduction in project latency we will see. Among the components of knowledge management, knowledge creation has the greatest effect (17.42%) on reducing delays and based on the calculated results, it can be said that about 96.8% of delays in projects can be controlled by knowledge management. Also, according to the descriptive statistics obtained in the general case, it can be said that the most important factor affecting the delays are the contractors at the rate of 21.35% and then the employers at the rate of 20.76%.

اجرای شمع‌های سنتی در محیط‌های شهری و ساحلی دارای چالش‌های متعدد، نظیر نیاز به تجهیزات و ماشین‌آلات حفاری سنگین، صعوبت دسترسی و مشکلات اجرایی در خاک‌های نرم و مسئله‌دار و مشکلات زیست‌محیطی نظیر سروصدا ، نویز و لرزش و . . . می‌باشد. از طرفی با توجه به توسعه تجهیزات متعدد هیدرولیکی و مکانیکی، مدل شمع‌های جدیدی در سراسر دنیا جایگزین شمع‌های سنتی نظیر شمع‌های فولادی کوبشی و یا بتنی درجا شده است. این مدل از شمع‌ها با استفاده از نیروی گشتاور هیدرولیکی با حداقل مشکلات اجرایی نظیر، حداقل ارتعاش، آلودگی صوتی و با سرعت بسیار بالا قابلیت نصب در مناطق با دسترسی پایین را دارا می‌باشند. در تحقیق حاضر با استفاده از تجهیزات متعدد هیدرولیکی و الکترونیکی دو مدل از شمع‌های متداول پیچشی و یک مدل شمع ابداعی جدید در ساحل بندر انزلی به عمق استقرار 20/3 متر نصب و موردمطالعه قرار گرفت. همچنین یک شمع فولادی لوله‌ای به‌عنوان مبنای مقایسه رفتار شمع‌های کوبشی با شمع‌های پیچشی نیز با ابعاد و عمق استقرار مشابه مورد آزمایش قرار گرفت. درمجموع 5 آزمایش بارگذاری استاتیکی فشاری بر روی شمع‌های اجراشده انجام گرفت و نتایج بررسی‌ها نشان داد که این مدل از شمع‌ها در کلاس شمع‌های با ظرفیت کم تا متوسط از ظرفیت باربری قابل قبولی برخوردار بوده و می‌توانند به‌عنوان جایگزین مناسبی برای شمع‌های سنتی در ساخت‌وسازهای شهری و ساحلی مطرح گردند. همچنین شمع ابداعی خودبازشونده با 600 نیوتن متر گشتاور کمتر نسبت به شمع هلیکال با ظرفیت باربری معادل با 160کیلونیوتن قابلیت بالای شمع ابداعی را مشخص نمود.

Due to the importance role of the behavioural characteristics of the project manager in construction projects and the need for effective and useful communication with other stakeholders of the project, studies have not comprehensively examined the behavioural competencies of the project manager and the lack of a practical model in the Iranian construction industry to select a capable project manager feels tangible. This research is on a more systematic approach to address the behavioural capabilities of the project manager by considering the factors related to his behavioural variables to evaluate the behavioural capabilities of the project manager. Using a multi-stage research process, including extensive literature review, analysis and a combination of important factors in the behavioural competencies of project managers, the development of an analytical network model (AHP, TOPSIS) was considered. This model would be a decision support tool for the employer organization to compare project managers according to their behavioural competencies by creating a database. This protects construction companies from the effective challenges posed by the performance of project managers and helps them to evaluate the performance of their project managers. It also enables project managers to focus on their efforts to address behavioural practices to improve their project performance.

Before the occurrence of Northridge earthquake,it was believed that the conventional connections used in steel moment frame structures were capable of tolerating the great plastic rotation of 0.02 radians and above without a significant reduction in strength.Observation of the applied damages by the 1991 Northridge earthquake showed that the main damage was in the area of welded connections.For this reason and the weakness in welded connections,the idea of using the link area in steel connections has been proposed, which can be easily replaced after an earthquake.Therefore, in this study,the box-shaped linking element has been developed,which acts practically independent of the applied load and has a steady hysteresis behavior under tension and compression.In this research, laboratory numerical study has been conducted RBS connection using the box-shaped replaceable link at the joint formation site.For this purpose,first a validation based on a laboratory model has been performed in Abaqus software.In the following, models based on the validation paper have been developed and the idea of using a box-shaped link has been proposed.Two models have been developed and analyzed in Abaqus and two laboratory models have been examined experimentally.Two links with different details were placed in the area of reduced joint to reduce the beam section.The results show that very high stress concentration occurs in the box-shaped link area and other parts of the beam and column elements of the stress surface are less than the yield point and energy absorption is done in the box-shaped link area.It was also found that according to the maximum rotation recorded in the specimens and according to the AISC regulations, specimen A is one of the allowable connections in the middle frame and, model B has the necessary conditions to be placed in the permitted connections in a special moment frame (tolerating rotation of above 0.04 radians).

The main need of sufferes in natural disasters, is to provide housing, especially to determine the place of temporary residence in critical situations. After the incident, it is not possible to provide suitable places for the injured immediately. Before such crises occur, proper planning must be done to determine the temporary residence so that the necessary infrastructure can be provided and in case of an accident in a crisis situation, it is possible to quickly set up camps for the injured. In this study, to determine the optimal location of temporary residence in Tabriz, various standards effect have been considered such as medical centers, fire brigade, faults, fuel stations, infrastructure facilities, worn-out tissue, watercourse complications. The desired standards were completed at first by experts and once again by experts in this field based on form of a questionnaire, then using the fuzzy hierarchical analysis method, the final weights of each standard were determined. Experts attributed the closeness to the worn-out texture and the second group of experts to the standard of avoiding faults the highest weight. That was important the avoiding standards to hazardous site and the river, for the both experts group. Finally, the last weights obtained the opinions of experts groups from fuzzy hierarchical analysis have been entered in Arc GIS software and the relevant maps that have been prepared using weight overlap in this research. The results show that before the incident, the western part of the city has suitable for temporary accommodation, and after the incident, the central part of the city is appropriate for settlement site. In addition, by comparing the vulnerability maps of Tabriz, the necessary locations for the construction of a temporary housing site were prioritized.

In this article, lateral-torsional stability of axially functionally graded (AFG) non-prismatic beam with doubly symmetric thin-walled cross-section under transverse loading is investigated. Material properties of FG beam with variable cross-section are supposed to vary through longitudinal direction of the constituents according to simple power-law distribution (P-FGM). Based on Vlasov’s model and using small displacements theory, the governing equilibrium equations are derived through the energy principle for AFG web and/or flanges tapered I-beams. The differential quadrature method is then selected to numerically solve the resulting system of governing fourth-order differential equations with variable coefficients. In this approach, a non-uniform mesh point distribution (Chebyshev-Gauss-Lobatto) is used for provide accuracy of solutions and convergence rate. Finally, the lateral-torsional buckling loads are calculated by solving an eigenvalue problem of the obtained algebraic system. In the case of homogenous members with variable cross-section, the outcomes of this work are compared with the available benchmarks and there is an excellent agreement. Finally, the impacts of involved parameters such as boundary conditions, load height parameter, power law index and web and flanges tapering ratios on the non-dimensional lateral buckling load are discussed. The results of this research reveal that the impacts of non-uniformity in the cross-section and gradient index play significant roles on lateral-torsional stability behavior of tapered I-beams. Furthermore, the highest buckling capacity is acquired when the transverse load is applied to the bottom flange.

Suspension bridges contain high towers due to having long span. Large height makes them to experience remarkable displacement responses against dynamic loading, like seismic excitation which disturbs their performance. In order to overcome this problem, control strategies, like tuned mass damper or in brief TMD as a passive system can be used. The performance of these systems can be addressed by the indices defined according to structural responses. On the other hand, its parameters should be adjusted to their optimum values to providing the best performance accessible by the meta heuristic algorithm. Here, the seismic displacement and energy responses of the Golden gate bridge considering soil-structure interaction were investigated using the optimum TMD optimized by observer teacher learner algorithm, and the performance of it was addressed by the energy indices. The results indicated that by increasing the softness of the bed soil the first mode plays the dominant role in the final response. Also, TMD was a successful system to control the vibration of the tower-pier system according to the defined energy indices for all the conditions of the bed soil considered. Suspension bridges contain high towers due to having long span. Large height makes them to experience remarkable displacement responses against dynamic loading, like seismic excitation which disturbs their performance. In order to overcome this problem, control strategies, like tuned mass damper or in brief TMD as a passive system can be used. The performance of these systems can be addressed by the indices defined according to structural responses.

In designing a structure, due to the uncertainty in some parameters, it is necessary to ensure that the design is responsive to the design requirements. For this purpose, the theory of reliability is used. In this study, the reliability of the low-rise steel moment-resisting frame was evaluated based on performance levels. For this purpose, based on the Monte Carlo simulation method, a step-by-step process was presented to use it to calculate the steel moment-resisting frame reliability index for probabilistic constraints of plastic hinges limitation and inter-story drift ratio limitation at each performance level. Also, cross-sectional area, moment of inertia and plastic section modulus of members, modulus of elasticity and yield stress of steel, and gravity loading are considered as random parameters in this study. Finally, using the presented process method, the reliability of a three-story steel moment-resisting frame, which is optimized based on the performance-based design method, was evaluated. The results show that in some plastic hinges at the performance level of immediate occupancy, the probability of plastic rotation less than the acceptance criteria of this level is not desirable, while in other plastic hinges and performance levels, a suitable reliability index was obtained for the probabilistic constraint of plastic rotation constraint. Also, based on the results, it is very unlikely that the inter-story drift ratio of stories will exceed the limits considered at each level of performance.