Zanyar Mirzaei

The durability of concrete curbs, as one of the essential components of urban infrastructure, particularly in cold regions, plays a decisive role in extending service life and reducing maintenance costs. This study was conducted to investigate and compare the durability performance of concrete curbs made with normal-weight concrete (NWC) and lightweight concrete (LWC) under freeze–thaw cycles. For this purpose, curb specimens were sampled from local production workshops in Sanandaj city and initially evaluated. Subsequently, new mix designs for both NWC and LWC incorporating Type II Portland cement and blended pozzolanic cement were developed and produced under laboratory conditions. compressive strength tests were performed at ages of 28 and 90 days, and durability evaluation was conducted according to ASTM C666 freeze–thaw cycling procedure. Results indicated that the compressive strength of workshop specimens at 28 days reached 17.7 and 19.4 MPa, which were approximately 29% and 22% lower than the target strength of 25 MPa, respectively. In laboratory-produced NWC, the 28-day compressive strength was 40.6 MPa for Type II cement and 32.5 MPa for pozzolanic cement, increasing to 44.4 and 38.7 MPa at 90 days. This reflects a higher long-term strength gain in pozzolanic cement concrete (6.2 MPa compared with 3.8 MPa). In LWC mixtures, the 28-day compressive strength reached 27.8 and 32.4 MPa and changed to 32.2 and 28.6 MPa at 90 days for Type II and pozzolanic cement, respectively. after exposure to freeze–thaw cycles, compressive strength reduction in NWC containing Type II and pozzolanic cement at 28 days was 20% and 22.5%, respectively, and decreased to 16% and 17.5% at 90 days. In LWC, the corresponding reductions were 30% and 35% at 28 days and 25% and 27% at 90 days. With increasing age, the durability difference between cement types diminished, and the performance of pozzolanic cement concrete approached that of Type II cement. Although lightweight concrete exhibited lower strength, it demonstrated a noticeable improvement in durability at later ages.

Chloride corrosion is a destructive phenomenon that adversely affects concrete and steel in concrete structures. These adverse effects become more significant when the structure is subjected to a sudden event, such as an earthquake, during its useful life. In such situations, the combined effect of the deterioration mechanism and a sudden seismic event becomes crucial. Various indices have been introduced to evaluate the performance of structures under these conditions, one of the most recent being the seismic resilience index. This index can be calculated in either a deterministic or probabilistic manner. Due to the uncertainty in the parameters required to determine the resilience index, this thesis discusses the evaluation of the probability of the mentioned index in reinforced concrete structures under chloride deterioration and damage caused by a sudden earthquake event. One of the challenges in the probabilistic estimation of the seismic resilience index is the reliance on static statistical distributions from references for input parameters. This approach, which ignores the real conditions of the structure, can lead to deviations in the results. To address this issue, this research presents an algorithm for updating the relevant distributions based on data obtained from field inspections of the studied structure. Using Bayesian statistics and real data, the algorithm corrects the statistical distributions used in the probabilistic calculations of the seismic resilience index for deteriorated reinforced concrete structures. Another challenge in the probabilistic estimation of the seismic resilience index is the high computational cost. This issue has led researchers to determine the semi-probability of the index. In this thesis, a method is proposed to reduce the volume of calculations, thereby enabling the estimation of full probabilities of seismic resilience and quantifying the uncertainty of the estimation. The proposed method employs the non-parametric maximum likelihood technique to calculate the most probable value of the index and determine its uncertainty. To evaluate the effectiveness of the proposed algorithms in this thesis, the seismic resilience index of a 20-year-old reinforced concrete school structure in Bandar Ganaveh was assessed. This structure has been exposed to chloride corrosion due to the extreme humidity and chlorine ions in the air. Field inspections were conducted to gather the necessary information for estimating the resilience index. Calculations were performed under various scenarios, including semi-probabilistic and full probabilistic approaches, and the results were compared with previous methods. The investigations indicated a more conservative estimate of the seismic resilience index when using the updated results for the structure. Additionally, the full probabilistic calculation demonstrated that the proposed method effectively reduces the uncertainty in estimating this index.

Self-compacting concrete (SCC), as one of the significant advancements in concrete technology, has gained widespread application in civil engineering projects due to its high filling ability, elimination of vibration, and improvement in the quality of concrete structures. In this study, the performance of three types of cement—including Type II Portland cement, composite blended cement containing 32% pozzolanic materials, and slag blended cement containing 30% ground granulated blast furnace slag—was investigated in the production of self-compacting concrete. The primary objective of this research was to identify and introduce sustainable alternatives to ordinary Portland cement in SCC mixtures, with the aim of reducing environmental impacts while maintaining or improving the workability and durability of concrete. accordingly, this research was designed and conducted with an industrial and practical approach, focusing on evaluating the performance of composite and slag blended cements in SCC and facilitating the direct application of the results in the production of precast concrete elements. In the first stage, rheological properties of SCC were evaluated using slump flow, V-funnel, L-box, and J-ring tests. Subsequently, compressive strength tests were performed at the ages of 7, 28, and 90 days, while electrical resistivity, rapid chloride penetration test (RCPT), and 30-minute water absorption tests were conducted at 28 and 90 days to assess the mechanical and durability properties of the concrete. the results indicated that SCC containing composite blended cement exhibited the highest flowability and filling ability, whereas SCC made with Type II Portland cement showed the greatest resistance to segregation. The slag blended cement provided a favorable balance between these two characteristics in terms of rheological performance. Although SCC incorporating Type II Portland cement demonstrated higher compressive strength at 7, 28, and 90 days, the long-term strength differences between Portland cement and blended cements decreased over time. In particular, SCC containing slag blended cement showed a significant increase in compressive strength at later ages, achieving performance comparable to that of Type II Portland cement. from a durability perspective, the results of electrical resistivity, RCPT, and 30-minute water absorption tests revealed that SCC mixtures incorporating blended cements exhibited superior resistance to chloride ion penetration and stray current effects compared to SCC made with Type II Portland cement. Overall, this study demonstrates that the use of blended cements not only enhances the performance and durability of self-compacting concrete but also offers considerable economic and environmental benefits through the reduction of clinker consumption.

1. Abstract. The thermal performance of concrete is a critical consideration in the design and safety of structural frameworks, particularly under fire exposure where the integrity of materials is paramount. Although conventional concrete exhibits commendable compressive strength, its intrinsic brittleness and limited tensile strength can lead to catastrophic failures in extreme conditions. Recent advancements in material science indicate that the incorporation of polypropylene (PP) fibers into concrete mixtures can enhance ductility, tensile strength, and crack resistance, thereby improving fire resistance in concrete structures. This study investigates the effects of various parameters, including temperature levels, fiber length, and polypropylene fiber content, on the residual mechanical properties of concrete subjected to elevated temperatures. A comprehensive review of existing literature emphasizes the pivotal role of PP fibers in mitigating the risk of explosive spalling during fire exposure by promoting the formation of a protective layer that curtails moisture loss and enhances thermal stability. Furthermore, the research examines the mechanical properties of concrete containing 12 mm and 16 mm polypropylene fibers at elevated temperatures of 450°C, 550°C, and 650°C. The evaluation includes compressive strength, ultrasonic velocity, peeling, as well as X-ray diffraction (XRD) analyses and Scanning Electron Microscopy (FE-SEM). While concrete inherently possesses notable fire resistance due to its low thermal conductivity and high specific heat capacity, the addition of PP fibers significantly augments its performance under fire conditions. The findings reveal an enhancement in the residual strength of concrete reinforced with 15 mm fibers compared to those with 10 mm fibers. Additionally, a polypropylene fiber content of 0.75% was found to optimize concrete strength at 450°C. However, it was observed that as temperature increased, the strength of the concrete diminished, with the 10 mm fiber-reinforced concrete exhibiting a more pronounced susceptibility to structural failure. The outcomes of this research contribute to the evolution of concrete materials with enhanced fire resistance, ultimately promoting greater structural safety in fire scenarios.

تیرهای عمیق بتن مسلح، اجزای سازه‌ای حیاتی هستند که به دلیل ظرفیتشان برای تحمل بارهای سنگین در دهانه‌های کوتاه، به طور گسترده در زیرساخت‌های عمرانی مورد استفاده قرار می‌گیرند. برخلاف تیرهای باریک سنتی، رفتار آن‌ها شامل توزیع تنش غیرخطی پیچیده و مکانیسم‌های مهار مستقیم است که نیاز به ابزارهای تحلیلی و محاسباتی پیشرفته برای ارزیابی دقیق مقاومت برشی دارد. این پایان‌نامه ارزیابی جامعی از مقاومت برشی تیرهای عمیق با استفاده از چندین رویکرد ارائه می‌دهد: مدل مهار و بست (STM)، روش اجزای محدود (FEM) از طریق ABAQUS، ACI و شبکه‌های عصبی مصنوعی (ANN) که در WEKA پیاده‌سازی شده‌اند. این مطالعه شامل دو بخش است. بخش اول با بررسی گسترده ادبیات آغاز می‌شود و پس از آن یک برنامه تجربی دقیق، دوازده تیر عمیق بتن مسلح را با نسبت‌های دهانه برشی به عمق، نسبت‌های آرماتور و مقاومت بتن متفاوت آزمایش می‌کند. محاسبات تحلیلی بر اساس شبیه‌سازی‌های STM و FEM انجام شده و غیرخطی بودن مواد و رفتار پس از ترک خوردگی را در نظر می‌گیرد. نتایج نشان می‌دهد که FEM پیش‌بینی‌های بسیار دقیقی، به ویژه برای تیرهای کوچک تا متوسط، با نسبت پیش‌بینی متوسط (FEM به نتایج تجربی) 0.92 ارائه می‌دهد. علاوه بر این، STM با نسبت پیش‌بینی متوسط (STM به نتایج تجربی) 0.96، عملکرد قابل اعتمادی دارد، اگرچه گاهی اوقات برای تیرهای بزرگتر تخمین‌های غیرمحافظه‌کارانه‌ای ارائه می‌دهد، زیرا چهار مورد از دوازده پیش‌بینی از 1 فراتر رفته‌اند. بخش دوم شامل تجزیه و تحلیل 233 تیر از مقالات علمی با در نظر گرفتن پارامترهایی مانند نسبت دهانه به عمق، نسبت دهانه برشی به عمق، مقاومت فشاری بتن، مقادیر آرماتور، نسبت عمق به عرض و قطر میلگرد طولی است. هر دو روش ACI و شبکه عصبی (WEKA) اعمال شدند. پیش‌بینی مقاومت برشی شبکه عصبی با ضریب تعیین 0.838 با نتایج تجربی مطابقت نزدیکی داشت، در حالی که پیش‌بینی آیین‌نامه ACI ضریب 0.394 را به همراه داشت. این پایان‌نامه با پیشنهادی برای یک چارچوب پیش‌بینی یکپارچه که قابلیت تفسیر STM، دقت FEM و سازگاری ANN را ترکیب می‌کند، به پایان می‌رسد. توصیه‌هایی برای بهبود آیین‌نامه‌های طراحی و هدایت تحقیقات آینده ارائه شده است.

One of the main challenges in civil engineering is to design better structures that can resist lateral loads caused by earthquakes and strong winds, along with their destructive effects. Conventional structures, even when designed according to current standard codes, may experience permanent deformations in structural members under large earthquakes. To achieve resilient and cost-effective buildings, structures must be designed to absorb and dissipate a significant amount of seismic energy. Since repairing and retrofitting earthquake-damaged structures is often expensive, time-consuming, or even impossible in some cases, and demolishing and rebuilding structures leads to resource waste, finding ways to improve structural performance and develop better design methods is of great importance. Over the past decades, numerous methods have been proposed and investigated by researchers to enhance the seismic performance of structures. Among the lateral load-resisting systems used in both low-rise and high-rise buildings, braced frame systems are among the most common and efficient. A fundamental drawback of conventional braces is buckling under compressive forces, which can lead to out-of-plane buckling during major earthquakes. This buckling reduces the lateral stiffness and strength of the structure and consequently diminishes its ductility. Devastating earthquakes have led researchers to focus on approaches that protect primary structural elements and localize damage to specific components, enabling better control of structural responses during strong ground motions. Given the importance of structural safety, improving system strength and ductility against lateral loads is crucial. However, this approach is costly, and it is more practical to use seismic response control systems and energy-dissipating dampers. Recently, innovative systems have been proposed and investigated by researchers to control damage caused by lateral forces on structures. In this study, the effect of the Rubber-Steel Core Damper (RSCD), a viscoelastic damper, on the performance of braced frames is examined. This metal damper can be used to reduce damage from strong earthquakes and allow for smaller primary structural elements. It consists of a combination of steel cores and a rubber layer and exhibits viscoplastic behavior. Under minor earthquakes, it operates in the elastic phase utilizing viscoelastic properties, while under large vibrations it yields and dissipates energy through its plastic behavior. The proposed system allows for easy replacement or repair after damage from lateral forces without requiring special procedures. The rubber layer, with high damping capacity, absorbs and eliminates small oscillations, while the ductile steel core limits damage to primary structural members by concentrating it within the core. This is the expected performance of this damper when installed in braced frame connections. After a major earthquake, the steel core can be replaced without the need to remove the entire damper and without additional labor. In this research, the effect of incorporating RSCDs in structures is studied through Incremental Dynamic Analysis (IDA) on two case study buildings. Fragility curves are then generated to evaluate and compare the performance of the structures.

In recent years, the growing emphasis on sustainable construction has led to an increasing body of research on the life cycle assessment (LCA) of buildings. While many studies have analyzed the environmental, economic, and social impacts of buildings throughout their life cycles, limited attention has been given to the sustainability implications of earthquake-induced repair activities. These repair activities significantly influence all three pillars of sustainability by causing economic losses due to repair costs and downtime, environmental damage through resource consumption and waste generation, and social impacts such as injuries and fatalities. Assessing the expected seismic damage of buildings requires understanding their structural behavior under seismic events, as insufficient resilience can lead to substantial damage and high repair demands. To minimize these impacts, researchers have examined various structural systems, often conducting comparative studies to identify those with lower economic and environmental costs and greater structural resilience. In the Iranian construction industry, a shift from steel structures to concrete structures has been observed in recent years due to factors such as material availability, cost, and advances in construction techniques. This transition underscores the importance of assessing the sustainability of these systems. This study aims to perform a comparative analysis of steel moment frames (SMF) and concrete moment frames (CMF) under seismic conditions, focusing on their environmental and structural performance. The findings will contribute to understanding which structural system offers superior sustainability, providing insights for future construction practices in earthquake-prone regions.

The fatigue of concrete structures is related to various environmental factors and external loads such as earthquakes, wind, and other forces. The formation of cracks in concrete structures has been a significant challenge in civil engineering and has garnered considerable attention from re-searchers. Artificial intelligence has opened new horizons in estimating and predicting cracks in this context. Machine learning, facilitated by extensive databases, including crack shape, size, and the load that caused it, processes data to estimate the load that created the crack based on its shape. Specifically, crack detection begins by using standard edge detection filters with appropriate ac-curacy to extract the crack shape. This research combines manual crack detection processes with machine vision algorithms and analyzes images taken from the shear walls of two buildings at the University of Kurdistan. For this purpose, the Otsu and Canny methods are employed for crack detection. In addition, studying crack patterns and determining properties of cracks, such as length, width, and angle, using standard equations and mathematical representations of cracks, are also used to understand their nature and cause. Combining the investigated methods is ultimately ap-plied to concrete structures considered real-world examples. The results obtained from these samples provide valuable information. The analysis results for these samples show that all observed cracks result from poorly executed concrete casting processes and thermal changes.

پل های بزرگراهی یکی از اجزای اصلی زیرساخت ها و شریان های حمل و نقل کشورها هستند. صرف زمان و هزینه زیاد و همچنین نیاز به نیروی کار زیاد برای تعمیر و نگهداری پل ها، اهمیت مدیریت زیرساخت های موجود و دوام و ماندگاری این زیرساخت را افزایش می دهد. از این رو نیاز به روشی برای ایجاد یک برنامه ریزی دقیق و کامل برای نگهداری پل ها حیاتی به نظر می رسد.. از آنجایی که بیشتر پل های ملی باید سالانه بازرسی شوند، حجم زیادی از داده های مربوطه وجود دارد که باید جمع آوری، ذخیره و تجزیه و تحلیل شوند. این مقدار داده می‌تواند منجر به عملکرد ضعیف در جمع‌آوری و ذخیره‌سازی شود و همچنین می‌تواند بر فرآیند تصمیم‌گیری برای تعمیر، بازسازی و ارزیابی پل تأثیر منفی بگذارد.. ایجاد یک نمایش دیجیتال قابل اعتماد از یک ساختمان یا زیرساخت موجود برای طراحی و تصمیم گیری، برنامه ریزی، پیش بینی، مدیریت عملکرد پل و امکان به روز رسانی اطلاعات و دسترسی به پروژه ها برای ذینفعان آنها در یک محیط دیجیتال از مزایای آن است. مدل سازی اطلاعات ساختمان زمینه را برای همه طرف های درگیر در پروژه برای تصمیم گیری مناسب فراهم می کند. مدل سازی اطلاعات ساختمان (BIM) یک فناوری مدل سازی است که در دهه های اخیر توسعه یافته و به طور فزاینده ای در طراحی، ساخت و مدیریت سازه های عمرانی به کار گرفته شده است. این فناوری نمایش دیجیتالی از ویژگی‌های سیستم ساخت و ساز را ارائه می‌کند که مبنایی قابل اعتماد برای تصمیم‌گیری در طول چرخه عمر پروژه ایجاد می‌کند و به ذینفعان زیرساخت کمک می‌کند تا تصمیم‌گیری کنند. مدل‌سازی اطلاعات ساختمان فرصت‌های جدیدی را برای ردیابی و بهره‌برداری از اطلاعات باز می‌کند و اطلاعات دقیقی را برای پیشبرد اهداف ارزیابی، نگهداری و مدیریت به طور کلی در اختیار کاربران قرار می‌دهد.یکی از کاربردهای BIM درنگهداری پل‌ها را می‌توان استفاده از این رویکرد در تعیین وضعیت المان‌های سازه ای مبتنی بر روش تحلیل ظرفیت به تقاضا برای المان‌های سازه‌ای و تاثیرنقش پایگاه داده در این امر اشاره کرد. در این پایان نامه تهیه ی مدل BIM از مطالعه ی موردی یک پل انجام شده است. به منظور بررسی و احراز شرایط سازه ای المانها و همچنین نیاز انها به تعمیر و نگهداری ، از تحلیل غیر خطی برای نمونه ی مورد بحث استفاده شده است. در پایان با توجه به نتایج به دست امده از تحلیل ، ظرفیت هر المان با توجه به شرایط موجود و نیاز پروژه مورد بحث قرار گرفته است و تصمیم برای تعمیر و نگهداری اتخاذ شده است.

There is scarcity in the fresh water supply across the globe. Due to the growth of the world population, water supply and demand balance should be restricted. The incremental demand for water, because of population growth and global urbanisation in recent years, has complicated water supply. On the other hand, infrastructures such as pipes are falling out of use due to erosion. The high rate of water demand and the population density in urban areas lead to the increase of water infrastructure loads which end in infrastructure deterioration. Also there a rise in the customer’s request for fresh water with high quality and low price. Therefore, new technologies are required in water infrastructures in order to provide customers with high quality, secure and affordable water. The functions of smart structure management system and structural condition monitoring are naturally interwoven and should be taken into account. However, most of the scientific studies in the filed of smart structure management system and structural condition monitoring are conducted independently. So an integrated framework is needed to fill the gap between these two fields of study and such an integration is vital to guarantee the best stable civil structure. The current study proposes a decision-making plan based on risk for infrastructure management according to structural reliability analysis. The potential performance is simulated by means of mechanical models which includes uncertainty by using variants or proper random processes. The successful accomplishment of this mission is a progressive step toward a transformation in the traditional methods based on visual review. As a result, providing structural managers with efficient tools for intelligent and timely decisions in monitoring, evaluating and maintaining obsolete civil structures means progress and a cut-down in the costs.

سطح جزئیات در مدلسازی اطلاعات ساختمان برای مراحل کلیدی پروژه ساخت تعریف می شود و به ذینفعان پروژه اجازه می دهد که مطابق با نیاز پروژه، میزان تبادل اطلاعات سازگار با پروژه را تعیین کنند و آن ها را قادر می سازد در مورد مراحل بعدی پروژه تصمیم بگیرند. سطح جزئیات مربوط به جزییات مولفههای مدل سازه می باشد و در مراحل پیشرفت پروژه از پایینترین سطح نمایش تقریبی (یعنی نمایش مفهومی) به بالاترین سطح نمایش (یعنی نمایش چون ساخت) تعریف می شود. در مرحله طراحی سازه ای ساختمانی به صورت سنتی، معمولا مدلی از سازه با جزییات مینیمم برای مدلسازی در نظر گرفته می شود. واضح نیست که آیا در نظر گرفتن پایین ترین سطح جزییات در طراحی سازه ای بهینه است یا خیر. هدف از انجام این تحقیق، بررسی تاثیر در نظر گرفتن سطح جزئیات مد لسازی BIM در تحلیل رفتار سازه تحت تاثیر بارهای لرزه ای است. در این مطالعه ابتدا آیین نامهها و استاندارهای مورد نیاز جهت مشخص نمودن سطوح LOD و تحلیل سازه بررسی و مقایسه شدند. مفاهیم و مدل هایی بر اساس استاندارهای موجود انتخاب شده و به عنوان مطالعه موردی مدل های ساختمانی مربوط به یک پروژه واقعی در سه سطح 200 LOD، 300 LOD و 350 LOD ایجاد و بررسی شدند. بر اساس تحلیل استاتیکی، طیفی و پوش اور نتایج مربوط به این مدل ها مقایسه گردیده و سطحLOD بهینه بر اساس پارامترهای برش پایه، منحنی ظرفیت، دریفت و دوره تناوب تعیین شد. مطابق نتایج به دست آمده در این تحقیق، پیشنهاداتی برای تحقیقات آینده ارائه گردید.

تحلیل و طراحی انواع مختلف سازههای عمرانی بر اساس عملکرد و مبتنی بر نظریه ی قابلیت اعتماد، به دلیل ماهیت تصادفی پارامترهای سازه ای درچند سال اخیر به صورت گسترده مورد توجه محققان قرارگرفته است. این نظریه به عنوان شاخه ای از تئوری عمومی احتمالات، دارای چارچوبی منطقی است که با احتساب و تجزیه و تحلیل عدم قطعیت های ناشی از طبیعت آماری مسائل مهندسی با استفاده از روش های عددی، امکان ارزیابی عملکرد و ایمنی یک سیستم سازه ای را فراهم می سازد. در این میان، روش های عددی از جمله روش اجزا محدود تصادفی نقش به سزایی در مکانیک محاسباتی تصادفی دارند. این روش در واقع بسطی از روشهای اجزا محدود کلاسیک با ماهیت تصادفی می باشد که برای کمی سازی عدم قطعیت یک مسئله به کار می رود و خروجی را به صورت شاخصهای آماری همچون مقدار متوسط، انحراف معیار و توزیع احتمالاتی پاسخ بیان می کند.در این پایان نامه، قابلیت اعتماد دیوارهای برشی بتن آرمه براساس نتایج تحلیل اجزا محدود غیرخطی تصادفی تحت بارگذاری یکنواخت و دوره ای ارزیابی شده است. جهت برآورد احتمال وقوع خرابی بر اساس تحلیل اجزا محدود تصادفی روش های متفاوتی وجود دارد .در این مطالعه روش مونت کارلو به عنوان یکی از مؤثرترین روش ها در شبیه سازی استفاده شده است. در ارزیابی قابلیت اعتماد دیوارهای برشی، پارامترهای مرتبط با خصوصیات مصالح بتنی، میلگردهای فولادی و بارگذاری بصورت تصادفی با توزیع های احتمالاتی نرمال و غیرنرمال در نظرگرفته شده و نتایج در سطوح عملکرد ایمنی جانی و آستانه ی فروریزش بدست آمده است. همچنین ضریب کاهش مقاومت بر اساس شاخص قابلیت اعتماد بدست آمده برای دیوارهای مورد مطالعه، پیشنهاد شده است. در ادامه تحلیل حساسیت پارامترهای تصادفی به منظور بررسی میزان تاثیر پارامترهای مختلف بر روی منحنی پاسخ بارجانبی-تغییرمکان دیوارهای بتن آرمه، ارائه شده است. بر اساس نتایج بدست آمده در این پایان نامه، بیشترین میزان حساسیت منحنی پاسخ، از میان پارامترهای تصادفی، مربوط به بارگذاری است. همچنین نتایج بدست آمده نشان می دهد که حساسیت منحنی پاسخ نسبت به بار جانبی بیشتر از بار مرده و زنده می باشد.