Amir houshang Akhaveissy

     ميراگرهاي تسليمي U-شكل   به دليل قابليت بالاي اتلاف انرژي، نقش كليدي در بهبود عملكرد لرزه‌اي سازه‌ها ايفا مي‌كنند. در اين پژوهش، رفتار چرخه‌اي اين ميراگرها با استفاده از روش اجزاي محدود در نرم‌افزار آباكوس مورد مطالعه قرار گرفت. در گام نخست، مدل عددي با استفاده از المان‌هاي حجمي هشت‌گرهي   و با در نظر گرفتن پيش‌تنيدگي پيچ‌ها ، بر اساس نتايج آزمايشگاهي معتبر صحت‌سنجي شد. براي كاهش تمركز تنش، يك هندسه پخ‌دار   پيشنهاد گرديد و سپس ?? مدل پارامتريك با متغيرهاي ضخامت، عرض، ارتفاع ، شعاع انحنا و زاويه بارگذاري تحت تحليل‌هاي استاتيكي غيرخطي قرار گرفتند. نتايج نشان داد كه افزايش ضخامت و عرض و همچنين كاهش شعاع انحنا، منجر به بهبود چشمگير سختي الاستيك، مقاومت نهايي و ظرفيت جذب انرژي مي‌گردد. در نهايت، يك رابطه تحليلي جديد براي پيش‌بيني سختي الاستيك ارائه شد كه نتايج آن با داده‌هاي عددي مطابقت مناسبي دارد. كلمات كليدي : ميراگر تسليمي U-شكل، روش اجزاي محدود، جذب انرژي، تحليل پارامتريك، سختي الاستيك

در اين تحقيق رفتار لرزه‌اي ساختمان بتني با تعداد طبقات مختلف با 3 سيستم باربر قاب خمشي بتني بدون ميراگر، قاب با مهاربند شورون و قاب با ميراگر   TADASمورد بررسي قرار گرفت. سازه‌هاي 5، 8، 12 و 15 طبقه مدل‌سازي و تحليل شد. مقادير برش پايه و جابه‌جايي نسبي در فاز خطي و جابه‌جايي نسبي در فاز غيرخطي بدست آمد. سپس ضريب بزرگنمايي ديناميكي محاسبه شد.   نتايج نشان داد كه براي سازه‌هاي با سيستم باربر قاب خمشي بدون ميراگر مقدار ضريب بزرگنمايي Cd   در سازه 5 طبقه برابر 9.157 در سازه 8 طبقه برابر 18.029 در سازه 12 طبقه برابر 26.522 و در سازه 15 طبقه برابر 48.606 بدست آمد. براي سازه‌هاي با سيستم باربر مهاربند شورون مقدار ضريب بزرگنمايي Cd   در سازه 5 طبقه برابر 9.35 در سازه 8 طبقه برابر 22.65 در سازه 12 طبقه برابر 21.34 و در سازه 15 طبقه برابر 57.582 بدست آمد.   براي سازه‌هاي با سيستم باربر   ميراگر مقدار ضريب بزرگنمايي Cd   در سازه 5 طبقه برابر 10.176 در سازه 8 طبقه برابر 21.96 در سازه 12 طبقه برابر 22.90 و در سازه 15 طبقه برابر 54.510 بدست آمد. براي سازه با ميراگر حداكثر ضريب بزرگنمايي ديناميكي در سازه 15 طبقه و برابر 54.510 بدست آمد. در مقايسه ضريب بزرگنمايي ديناميكي Cd براي سازه‌هاي با سيستم باربر مختلف و تعداد طبقات 15 طبقه نتايج نشان مي‌دهد كه براي قاب خمشي برابر 48.606 براي مهاربند برابر 57.582 و براي ميراگر برابر 54.510 بدست آمد.   در مقايسه ضريب بزرگنمايي ديناميكي Cd براي سازه‌هاي با سيستم باربر مختلف و تعداد طبقات 12 طبقه نتايج نشان مي‌دهد كه براي قاب خمشي برابر 26.522 براي مهاربند برابر 21.34 و براي ميراگر برابر 22.90 بدست آمد. در مقايسه ضريب بزرگنمايي ديناميكي Cd براي سازه‌هاي با سيستم باربر مختلف و تعداد طبقات 8 طبقه نتايج نشان مي‌دهد كه براي قاب خمشي برابر 18.029 براي مهاربند برابر 22.65و براي ميراگر برابر 21.96 بدست آمد.   به‌عنوان نتيجه گيري كلي مقدار ضريب بزرگنمايي ديناميكي Cd با توجه به نوع سيستم باربر و طبقات متغير است. براي سازه با ميراگر در تعداد طبقات 5 طبقه اين ضريب از قاب خمشي و مهاربند بيشتر بدست آمد. براي سازه‌هاي 8 طبقه ضريب بزرگنمايي ديناميكي در سيستم باربر مهاربند بيشترين مقدار بدست آمد. براي سازه‌هاي 12 طبقه ضريب Cd براي سازه با سيستم باربر قاب خمشي بيشترين مقدار بدست آمد. براي سازه 15 طبقه ضريب Cd براي سيستم باربر مهاربند بيشترين مقدار بدست آمد. كليد واژگان: ضريب بزرگنمايي ديناميكي، قاب‌هاي خمشي، مهاربند شورون، ميراگر TADAS   

Concrete, as the most widely used construction material, is constantly exposed to aggressive environmental factors that reduce its durability and mechanical performance. Among these factors, sulfate attack and calcium leaching are considered the most critical deterioration mechanisms, simultaneously inducing chemical and mechanical weaknesses in concrete. This research was conducted to evaluate the mechanical behavior and durability of concrete under the combined effect of magnesium sulfate and ammonium nitrate solutions. For this purpose, standard concrete specimens were exposed to the aggressive environment for two durations (0 and 30 days) and subsequently assessed through mechanical, physical, and microstructural tests. The mechanical tests revealed that compressive strength decreased by 37.7%, from 28.95 MPa to 18.04 MPa, within 30 days. Moreover, tensile strength and fracture parameters, including fracture energy and fracture toughness, exhibited significant reductions in both notch geometries (0.1 and 0.5), indicating increased brittleness of the cementitious matrix. Physical tests further showed longitudinal and volumetric expansions caused by the formation of expansive phases such as ettringite and gypsum, which accelerated deterioration through microcracking. In contrast, weight change was minimal, suggesting that the dominant processes were related to structural and chemical alterations rather than mass gain. Microstructural analyses using SEM and EDS confirmed a notable reduction in calcium content and a decline in the Ca/Si ratio in 30-day specimens. These findings indicated the weakening of the C–S–H phase and increased porosity, which were directly correlated with strength loss and higher brittleness. Overall, the results demonstrate that the combined sulfate–nitrate environment can cause severe deterioration of the mechanical properties and durability of concrete even within a short exposure period of one month. From a practical perspective, these outcomes highlight the necessity of employing low-permeability mix designs, pozzolanic materials, and protective coatings in similar structures. Furthermore, the experimental data can serve as a basis for developing standards and design strategies aimed at extending the service life and reducing the maintenance costs of concrete structures.

  سيستم مهاربندي كمانش تاب با استفاده قابليت استهلاك

Currently, heavy machinery is used in the world to tra  ort and construct roads. To speed up the implementation of road construction, fabric concrete was investigated. One of the ways to speed up the implementation of asphalt is to use fabric concrete, which is easier to carry, higher transfer speed, and does not require a lot of time to gain strength, making fabric concrete more attractive than other methods and materials. In this research, using the software analysis method, it has been tried to investigate the effect of using fabric concrete on asphalt tensile strength and pavement strains. This research is expected to reduce the thickness of the asphalt layers, the base and sub-base and the use of fabric concrete, the cost and time of the projects will be reduced and it will also increase the tensile strength of the asphalt. On the other hand, this change will increase the pavement life and reduce Damages and settlement of the asphalt layer. Research methodology: In the current research, the analysis method is finite elements using ABAQUS software. Now we intend to reduce the thickness of the asphalt layer, base and sub-base by using fabric concrete reinforced with aramid fibers and adding it with asphalt. And increase the tensile strength of the asphalt pavement, which our modeling has been done using the available past articles and researches. In this research, we have made 8 pavement models, one without fabric concrete and four other models It is with fabric concrete with different thicknesses and three end models by reducing the thickness of the asphalt and removing one of the base and sub-base layers, and we compare the results and analyzes obtained from the Abaqus software with each other. Conclusion: According to the obtained results: with the addition of fabric concrete, the tensile strength of asphalt is increased and the thickness of the base and sub-base layers can be reduced, and the strains created in these layers experience a significant reduction. Reducing the strain and increasing the tensile strength of the layers has reduced the damage caused to the surface of the pavement and controls the settlement of the asphalt layer and has created roads with higher safety and less risk of accidents.   

  ased on the studies and investigations carried out and with the aim of designing and producing an effective and practical structural damper in the consumption of earthquake energy and high ability to protect the structure against damage caused by earthquakes with the ability to install and replace easily and also cost-effectively. From an economic point of view, after examining many mechanisms and presenting various initial ideas, a damper with an energy consuming mechanism based on cyclic bending of cheap steel rods was designed and built. In such a way that these inexpensive rods, after bearing the cyclic load and deformation of the plastic, and after losing their ability to absorb energy due to the deformation of the plastic, can be easily replaced with a new rod. So, our damper will be serviceable again.

  The increasing construction of high-rise structures in cities and the placement of buildings on soils with different layers show the need for engineers to pay attention to the effect of different conditions of soil layers on the seismic response of structures. In this study, after validating the 3D numerical model using the previous shaking table test, the effect of soil layering on the seismic response of resistant concrete buildings has been investigated by considering the soil-structure interaction (SSI). Using Abaqus finite element software, a set of numerical modeling for a 15-story building placed on layered soil with different values of shear wave velocity has been simulated. Nonlinear dynamic analysis under seismic motion has been performed in a direct way and the results have been compared and discussed in terms of maximum lateral displacement, shear force, maximum relative displacement of floors and acceleration response spectrum. The results showed that the deeper the soil layer with the lower shear wave speed and the closer it is to the ground surface, the higher the values of lateral displacement and shear force, the relative displacement of layers and the acceleration response spectrum. Also, according to the results, soil layering has a major contribution to the seismic response of buildings by considering SSI, and considering SSI ensures the safe and economical design of structures. Keyword: soil-structure interaction, numerical modeling, soft soil, abacus, relative displacement, floor shear

   استفاده از مقاطع توخالي در اعضاي باربر سازه، مزيت كاهش وزن مخصوص را دارند؛ كه به سبب وزن كمتر، عملكرد بهتري را در مقابله با زلزله از خود نشان مي­دهند. الياف موادي ايده­آل براي استفاده در بتن و ملات­ها مي­باشند و استفاده از الياف در بتن سبب افزايش مقاومت در برابر آتش، سختي، افزايش مقاومت فشاري، خمشي و كششي و دوام مي­شود.پوشش­هاي FRP سبب افزايش ظرفيت باربري ستونها مي­شوند؛ و در سازه­هاي فرسوده واقع در مناطق لرزه­اي، به منظور بهبود شكل­پذيري و به تعويق انداختن شكست ناگهاني، كاربرد دارند. در اين پايان­نامه به بررسي و مقايسه مقاومت شعاعي و مقاومت در برابر حرارت بالا نمونه­هاي استوانه­اي توخالي بتني پرداخته مي­شود؛ بدين صورت كه نمونه هاي بتني، بتن اليافي و بتن با پوشش FRP به صورت استوانه­اي توخالي جدار نازك ساخته خواهد شد و سپس مقاومت شعاعي و مقاومت در برابر حرارت بالا نمونه ها اندازه­گيري و با يكديگر مقايسه مي­شوند.

AbstractSteel shear walls are considered as one of the lateral force-resisting systems in build-ings. Sometimes, openings are created inside these walls due to architectural needs and the passage of facilities, which causes the interruption of the power flow inside these walls, and has a negative effect on the structural behavior of these walls. There-fore, this study was carried out aimed to improve the behavior of these types of walls by using elements that will remain in the elastic range and bring their behavior closer to the behavior of the wall without opening. In this study, a laboratory sample of these walls, which has been done before, is first modeled using Abaqus FEA (formerly ABAQUS), and will be subjected to the same laboratory loading and with an increase in the elastic part. The elastic part of the wall's performance will be checked in differ-ent situations after ensuring the correctness of the modeling according to the corre-spondence between the software answer and the laboratory work by changing the ge-ometrical characteristics, and the best reinforcing technique will be selected from among the reviewed cases.Keywords: Steel wall with opening, Cyclic loading, Reinforcement  

  Iran's Standard No. 2800 provides a code for the design of structures against earthquake loads. Due to the fact that mostly, far-field records have been used to prepare the seismic design spectra, in order to consider the destructive effects of near-field earthquakes in the 4th edition of St.2800, the incremental spectral correction coefficient (N) was introduced. In this paper, the accuracy and estimation of the value of this coefficient for 5 structures of special reinforced concrete moment-resisting frame with the number of floors from 3 to 15, are evaluated. Due to the fact that the increase in seismic requirements under the pulses of near-fault earthquakes is not the same for all seismic response parameters, so different correction coefficients can be used to estimate displacement response quantities and force quantities. For this purpose, first, the structures are statically analyzed according to the criteria of Iranian Standard 2800 and are designed according to the criteria of Article 9 of the National Regulations of Iran. Then the dimensions of beams, columns and rebars required by the structures are determined. After that the response spectrum of single-degree of freedom system to a set of records (including 7 far-field records, and 22 near-field records) is calculated, then using incremental dynamic analysis, the seismic response of structures at different seismic intensities is calculated. By calculating the response ratio of structures under near-field records to far-field records, the value of the N-coefficient is calculated. Based on the results, the value of the N-coefficient of the standard spectrum of St.2800 is suitable for estimating the base shear demand of structures, but this coefficient is not accurate enough to estimate the need for lateral drift of structures. In general, the coefficients obtained from elastic and inelastic analyzes for the need for displacement in reinforced concrete flexural frame structures are higher than the values provided by the St.2800. This difference has reached 58% in some structures. It was also observed that there is no regular relationship between the 1st natural period of the structures and the magnitude of the spectral correction coefficient and the magnitude of the spectrum correction decreases with increasing seismic intensity.

  Usually, most of the destructive earthquakes that occurred in Iran and left many casualties and damage were near earthquakes. Earthquakes such as Manjil 1369, Bam 1382 and Sarpol-e Zahab 1396 are examples of these near-field earthquakes that occurred in Iran. Determining the performance and evaluating the structure and its components is important to determine the seismic capacity and requirements. Due to the fact that most instruments enter the nonlinear area during moderate and severe earthquakes, so estimating the exact capacity of the structure requires the use of more efficient methods in the science of structural analysis. In the analysis and design of structures according to the type and manner of application of loads on the structure and the philosophy of seismic design and the occurrence of nonlinear behavior under the forces on the structure due to earthquakes, in order to determine the exact behavior of the structure is necessary. Different nonlinear dynamic analyzes are used. Dampers are considered as the best method to control and improve the behavior of structures as well as to improve the performance of structures. The main purpose of the thesis is to investigate the seismic performance of flexural frames of reinforced concrete equipped with rotary friction dampers. The results showed that the coefficient of increasing resistance for medium flexural frames equipped with dampers was obtained according to the overlay analysis of 2.63 and based on nonlinear dynamic analysis of 2.90. The obtained ductility coefficient for flexural frames with medium ductility equipped with dampers according to the cover analysis is 2.52 and based on nonlinear dynamic analysis is 3.15. The behavior coefficient for medium bending frames equipped with dampers was 6.56 according to the cover analysis and 8.83 according to the nonlinear dynamic analysis. The coefficient of increasing resistance decreases with increasing number of classes, while the coefficient of behavioral ductility has the opposite. The damper improves the three factors of increasing strength, ductility and modifying the response (coefficient of behavior) according to nonlinear dynamic analysis, while the other analysis of the ductility factor for short structures shows the opposite.

   Deep beams as the most important bending-shear member are widely used in a variety of structural and non-structural structures. The cross-sectional height of these beams is higher than that of ordinary beams, so that according to the American Concrete Code, in deep beams, the cross-sectional height is greater than four times the length of the span. Analysis and design methods in deep reinforced concrete beams differ from ordinary beams due to their unique properties. Closing method is one of the most common methods in the analysis and design of deep beams. In this research, the mentioned method as one of the main topics was reviewed and some examples of existing experimental models were analyzed and evaluated. In order to study the details of the mentioned model, 432 laboratory samples with simple support and concrete efficiency coefficient were collected and examined from the laboratory researches carried out in recent years, considering the effect of reinforcing reinforcements where the total shear force applied to the beam is borne by two independent supports. The most important purpose of this study is to provide a formula for predicting shear strength by considering all effective factors. To achieve the project goal, numerical studies based on artificial intelligence were performed. Artificial intelligence is a computational method that tries to mimic human cognitive ability in a very simple way to solve engineering problems that have disregarded common computational techniques. Next, according to the experimental results, a new fastening model that included a wide range of deep beams with different arrangements of shear reinforcement, concrete strength and effective shear-height ratio was investigated. In this study, the shear capacity of deep beam specimens that have been tested by different people so far was calculated and the results were compared with the actual values ??and results of several other existing bonding methods. The results of the comparison indicate the satisfactory accuracy and efficiency of the proposed model. The proposed method is able to predict the shear strength of simple deep beams with acceptable accuracy.

  One of the methods for stabilizing earth slopes or excavated ditches is soil nailing, which has been used around the world for about fourteen decades, and many advances have been made in the use of this method. Has been. However, the use of this method in cold regions is more limited than other places with normal temperature conditions due to lack of sufficient studies and lack of necessary information about the response of the nailed earthen wall due to the experience of freezing and thawing cycles. Therefore, in the present study, in order toachieve a comprehensive plan for the proper design of nailed earthen walls in cold regions, using ABAQUS finite element software, numerical modeling of a nailed earthen wall in Brunswick, Maine The United States has made this region one of the coldest regions. The purpose of this study was to numerically investigate the effect of freezing phenomenon on the behavior of nailed earthen wall, to investigate the stresses caused by freezing activity in the nails that strengthen the earthen body, the amount of pressure on the top wall and the amount of body displacement. Soil is the result of experiencing the freezing process. The results obtained in this study are validated based on the results of field operations performed in Brunswick (Duchesne 2003). Finally, in orderto achieve more comprehensive results, the effect of different nailing conditions inside the soil body under the .mentioned conditions has been investigated

In today's world, developments are happening very fast and civil engineering plays an important role in providing the basis for the current developments in the world. Concrete and concrete technology have also undergone significant improvements in line with these changes. Reactive Powder Concrete (RPC) is a new type of high-strength concrete (UHPC) and a cement-based material developed through microstructural engineering. This type of concrete was first introduced in France in the 90's by Richard P, Cheyrezy M and has been able to eliminate many of the weaknesses of conventional high strength concretes and much research has been done on this subject in the world of science and and It is also being done. During our research and studies, new angles of this type of concrete attracted our attention and we decided that part of our future research on improving the mechanical properties and improving the quality of reactive powdered concrete and the other part, trying to Addressing weaknesses and shortcomings that have not been addressed to date. We intend to replace the additives with suitable and economical properties and available in the country as an alternative to cement and green reactive powder concrete with a new mechanism and concretes with excellent properties and higher environmental compatibility to produced. In order to increase the final quality of the produced reactive powdered concrete, additional tests were performed to identify the properties of aggregates, modify the granulation of materials and also to perform super-lubricants tests in order to identify materials and materials to control their properties. In this research, two types of heat treatment and standard, as well as in two projects, the effect of internal processing and also the effect of using burnt oil and comparison with standard mold oil with fresh and hardened concrete tests have been done. By using the optimal percentage of microsilica, metakaolin and natural zeolite pozzolans and steel and polypropylene fibers, along with the use of sand and quartz powder as a substitute for part of the sand, we were able to reduce cement consumption by up to 25% and also the percentage of microsilica use. In order to make the design economical, it has been minimized and at the same time produced concrete with very suitable properties and with increasing resistance compared to the control sample, with a compressive strength of up to 173.2 MPa, a tensile strength of 13.1 MPa with a water absorption of 0.9% produced.   

Historical buildings areelements of cultural inheritance of each culture and nation which trying toprotect and keep it is the generation's responsibility. Different factors causedamage to buildings . One of the harmful factors of historical building especiallybrick and dried brick buildings is Rising moisture which is the reason ofdepreciation of historical buildings. Many of researchers are also trying to beable to create a method to remove the presence of Rising moisture fromhistorical buildings.Tekih Moaven Almolk is oneof the historical buildings and tourist attractions of Kermanshah in which theclimbee moisture has been presented and appearanced there during the recentyears.according to the fact that the Rising moisture phenomenon in Tekih MoavenAlmolk is the consequence of the high ground water surface and the ground wateris made by capillarity property of this brick building, the most fundamentwayceto remove this phenomenon is decreasing the ground water level. decreasing the ground waterlevel is formed by drainaging the Tekih's earth by making drain pipe pits.In this research they haveused the studys and geotechnical reports of the place for model building of theground geometry and geo technique parameters. Tekih's geometry in modelbuilding is defined by produced plans in the place as an incorporated solid andrelated to inelastic behaviour. The amount of wall'selasticity is defined by doing Schmidt hammer test in Tekih Moaven Almolk andaccording to FEMA regulation relations in three different amounts and has beenallocated to Tekih's geometry. In this research 4 kind of site plot plan ofdrain pipe pits have been placed in three depth of 4,6 and 8 meters with threekinds of wall with different amounts of elasticity. In the process of modelbuilding of this research at first the ground becomes a model with drain pipepits and then the Tekih's building is placed on the ground and the analysis iscontinued until the form changes will be finished and then reach the ganglionicwater pressure in the Drainage Wells pits to ziro in order to do the drainageactivities.

  The presence of Iran on the Alpide earthquake belt highlights the need for a study on the behavior of structures and their robust design. Therefore, researchers are seeking to improve seismic behavior of buildings using different methods. One of these methods is the use of composite concrete columns (CFT). In this research, the aim is studying the effect of these kind of columns on the seismic behavior of steel structures. The results of this research can show the effectiveness of this system.In this research, lateral displacement diagrams of the structure in relation to time in seven earthquakes and with different systems of lateral load resisting, including moment resistance frame, x bracing and steel plate shear wall are presented. In addition, lateral displacement diagrams of the structure are presented in relation to the time of a type of lateral lateral load resisting system in different earthquakes.In this study, the seismic behavior of a steel structure with a lateral load resisting system of steel plate shear wall and concrete composite columns and compared to steel structures with bracing systems and bending frame with ordinary columns will be considered. For this purpose, three structures of 10-story steel structures with a steel slab loading system, a 10-story steel building with a bracing system and conventional columns, and a 10-story steel building with a moment resistance frame and conventional columns will be analyzed.

  Concrete is one of the most widely used and widely used building materials, which has been especially welcomed in the construction industry due to its easy access and low cost components. One of the most important parts of concrete construction and operation is its processing part, which is necessary to achieve the desired strength, and especially in our country, little attention is paid to it. Lack of proper processing can reduce the mechanical and durability properties of concrete and cause damage to the concrete structure. On the other hand, concrete can be exposed to damage for various reasons, sometimes we need to repair these defects, which can be much more difficult to process the repaired parts, in the presence of materials in Inside the concrete that performs this action, the concrete can achieve the required strength without external processing. Polymeric superabsorbents are a group of materials that can absorb several times their own weight of water and over time this water is removed from their structure, so their type of performance affects the structure of concrete. Concrete samples constitute the statistical population of the research and their construction is in accordance with the standards of Concrete Laboratory (ASTM). In this study, concrete was evaluated by adding two types of polymer superabsorbents in the amounts of 0.6,0.3 and 0.9 and one type of powder polymer in the amounts of 1 and 2 wt% of cement in the ratio of water to fixed cement 0.38. Our evaluation tools in this research are concrete laboratory devices such as concrete compressive strength measuring device, concrete slump cone, etc. We found that the polymer superabsorbents used in this study reduce the flow of concrete. Permeability of concrete is one of the parameters for evaluating its durability, which is reduced by adding polymer superabsorbents, which increases its durability. Polymeric superabsorbents reduce the compressive strength of concrete, which is partially compensated by the addition of ethylene vinyl acetate. At 0.3% by weight of cement, they increase the compressive strength compared to the control sample without processing. They increased the energy absorption compared to the control sample without processing. At 0.6% and 0.9% by weight of cement, the modulus of elasticity decreased. Were observed in concrete, and the addition of ethylene vinyl acetate exacerbates this reduction.

Today, concrete and cement mortars are one of the most widely used building materials. On the other hand, the weaknesses of concrete and failures in projects for various reasons, improving the properties and eliminating the weaknesses of concrete have been considered by researchers. Due to the advancement of technology and materials science, he tried to improve these high-consumption materials by adding new materials and recognizing it. Although adding these materials improves some properties, on the other hand, it weakens others. Civil engineers must use and update their knowledge, according to the place and the need for the best and most optimal form of materials and materials. Polymers and biopolymers are one of the materials used today to improve the properties of concrete. In this study, we investigated the effect of three different types of cellulose and one type of vinyl acetate-ethylene on the properties of concrete. Cellulose Ether is a derivative of cellulose, the most abundant organic molecule on Earth that can be used to improve some properties of concrete and mortar. Cellulose ethers are used in many polymer-modified mortars such as cement coatings, building mortars, tile adhesives, surface coatings and self-compacting concrete. The use of cellulose ethers in cement mortars began in 1960 and to date, several studies have been conducted on the effect of these materials in cement mortars and concrete. Another material used in this study is vinyl acetate, which causes the loss of water in the concrete, which helps the concrete to work. In addition to examining these two substances separately, the combination of these two substances was also examined. According to the performed experiments including slump, air percentage, compressive strength, tensile strength and water absorption, the design of different mixtures of mechanical properties and durability of concrete was investigated. In all samples, for better comparison, the ratio of water to cement is considered constant. The results of increasing energy absorption and decreasing water absorption and decreasing modulus of elasticity were observed in most of the mixing designs. Regarding compressive and tensile strength, materials with different percentages had different effects on these properties of concrete.

  Concrete is the most widely used material in the world after water. Today, concrete is used much more in structures and construction projects than in the past, so that billions of tons of concrete are used annually in the construction of structures. Due to the rapid advancement of technology in order to save energy, the time and cost of construction projects, new methods and materials have replaced the old methods and materials. One of the newest and most unique concrete products is the concrete canvas, first proposed in 2005 by Berwin and Crawford. Concrete canvas is a composite with cement properties, which can be used in less than 24 hours to achieve a desirable concrete surface with low thickness, waterproof, fire resistant, etc. . In this study, in order to introduce this product, an attempt has been made to investigate the tensile behavior of concrete canvas according to different geometric patterns of 3D fabric, so that to increase the tensile strength in the warp and weft of concrete blanket fabrics. The results obtained were that the larger the number of layers, the smaller the diameter of the hole in the top layer of the fabric and the higher the density of the spacer yarns, the tensile strength of the concrete canvas. It is higher and also the rate of increase of resistance in the direction of weaving is more than the direction of the warp.

   Abstract In resent years, FRP composites have broadly and successfully been used to improve seismic behavior of the structures. Great resistance of these materials against erosion together with the high ratio of strength to weight in these materials are the reasons why strengthening the structure by using these materials do not impose extra weight to the structure, unlike the traditional methods in which shotcrete or ferrocement are used. Beam-column connections in reinforced concrete moment frames are critical points in performance of reinforced concrete moment frame during the earthquake. Many studies have done on reinforcement of beam-column connections in reinforced concrete frames using FRP materials. Most of these studies are done in micro scale on shear strength and ductility of connection, and some solution are provided for its improvement, and little studies have done on seismic parameters such as behavior factor of reinforced concrete frame, the amount of energy absorption, and loading and displacement capacity of the frame reinforced with FRP in connection point in macro scale. In this thesis to numerically investigate the behavior of beam-column connection in reinforced concrete buildings in macro scale using finite element theorem, and some solutions are recommended for reinforcing and improving their seismic performance using FRP composites. In contrast of experimental samples which have many constrains for observing and obtaining results, in finite element modeling, these constrains are fewer, and it is easier to model a sample nearer to reality.   

Performance evaluation of unbounded fiber-reinforced elastomeric isolators against wind

اين تحقيق به منظور نشان دادن تاثير زواياي گوشه و هندسه گودبرداري بر روي تغييرشكل­ ها و سطوح گسيختگي اطراف گود ميخ­ گذاري شده، انجام شده­است. در اكثر تحقيقات صورت گرفته به بررسي و تحليل عناصر پايدارسازي ديواره‌ي گود با فرض كرنش مسطح و به‌صورت مسئله دوبعدي پرداخته شده­ است، حال آن‌كه مسئله‌ي پايداري در گوشه‌هاي گود و اثرات هندسه و شكل گود از جمله موضوعات مهم و تاثيرگذار بر پايداري و كنترل تغييرشكل‌ها و سطوح گسيختگي مي­ باشد. در اين تحقيق از نرم‌افزار اجزاء‌محدود Abaqus CAE-2016 استفاده شده و مدل­رفتاري مورد استفاده در اين تحقيق موهر-كولمب در نظر گرفته شده ­است. عمده تمركز اين تحقيق بر تغييرشكل سه ­بعدي گود و نشان دادن اثر گوشه‌ي گود است به همين منظور بررسي تغييرشكل‌هاي افقي و قائم گود و سطوح گسيختگي آن انجام ‌مي‌گردد. در اين تحقيق براي بررسي اثر هندسه و گوشه گود، 4 حالت مختلف براي گوشه گود در نظر گرفته ‌شده ­است؛ حالت گود مقعر با زاويه­ ي گوشه 60درجه، 90درجه، 120 درجه و حالت گود محدب با زاويه ­ي گوشه 270 درجه؛ كه براي هر كدام از حالت‌هاي ذكر شده از سه مدول الاستيسيته مختلف براي ميخ‌ها بررسي گرديده كه بتوان تاثير همزمان بازدارندگي گوشه گود را با تغيير مدول الاستيسيته ميخ‌ها بررسي كرد. با استفاده از تحليل­هاي عددي اثر مدول الاستيسيته و اثر زاويه گوشه گود بر‌روي تغييرمكان‌ها و نشست‌هاي ايجاد شده با فاصله گرفتن از سطح ديواره‌ي ميخ‌گذاري شده و تغييرشكل ديواره گود در گوشه‌هاي گود با ديوار ميخ‌گذاري شده و محل سطوح گسيختگي بحراني در حالت سرويس مورد ارزيابي قرار مي‌گيرد. در اين تحقيق بار سرويس متشكل از بار يكنواخت 135kpa بر روي سطح كل گودبرداري است. كه نتايج كلي مشهود از اين تحقيق، تاثير بازدارندگي گوشه‌هاي گود مقعر مي باشد، به‌طوري كه هرچه گوشه گود داراي زاويه‌ي كمتري باشد اين تاثير بازدارندگي در نشست‌هاي سطحي و تغييرمكان افقي ديواره­ي گود بيشتر است اما با كم شدن بيشتر زاويه گوشه اين تغييرات كمتر شده و بهينه نيست، بهترين زاويه كه تاثير بازدارندگي بهينه را دارد زاويه 90 درجه مي­باشد. براي حالت محدب عكس اين موضوع اتفاق مي‌افتد و اثر تحدب در گوشه باعث ناپايداري در گود افزايش در مقدار نشست‌ها خواهد­شد. تاثير سختي ميخ‌ها نيز مشابه تاثير گوشه گود است به طوري كه با افزايش سختي، كاهش در مقدار نشست‌هاي سطحي و تغييرمكان افقي ديواره­ ي گودبرداري مشهود مي‌گردد. در حالت محدب كه گود به حالت ناپايداري نزديك مي‌شود مي توان با ميخ‌هايي با سختي زياد اين اثر افزايش نشست را   تا حدود زيادي كاهش داد. كرنش­ هاي برشي پلاستيك باعث ايجاد 2ناحيه در گودبرداري مي­گردد،­ با نزديك شدن به گوشه گود، ناحيه 2 كه ناحيه­ اي فعال و محرك است به تدريج از ناحيه 1 كوچك‌تر شده و گود پايدارتر مي­گردد، اين اثر زاويه گوشه بر روي گوه­ هاي گسيختگي به اين شكل است كه با كوچك‌تر شدن زاويه گوشه تا 90درجه اين تاثير چشم گير است اما با كاهش بيشتر آن تغيير زيادي نسبت به مدل 90درجه مشاهده نمي­ گردد. براي حالت محدب نيز گوه­ هاي گسيختگي بسيار به لبه گود نزديك شده و حالت بحراني رخ مي­ دهد.

Abstract Building frames are usually filled in the periphery and middle of the building with masonry walls as internal or external walls, which makes the difference between such frames with empty frames. These type of walls are said to be infill panel and to the interaction of the frame and the infill panel said to be composite frame or filled frame. In the steel frames with saddle connection, as in the other types of building frames, there are infill panels that are usually made of masonry materials and their effect on structural analysis is ignored. However, in the event of intense and moderate earthquakes, the creation of interaction forces between the environmental frame and infill panel increases the bearing capacity of the structure. This interaction can be beneficial or harmful for the structure.   In many studies, researchers have compared the behavior of the composite frame with empty frame, which in part of   this thesis this topic has been reviewed, and few have exploring the comparison of the composite frame behavior to the infill panel. Therefore, an attempt has been made to examine this topic in another part of the thesis. Fore numerical modeling, the ANSYS software has been used. The masonry wall is modeled in macro approach with using laboratory test results. In the macro modeling that was used in this study, the masonry wall is assumed to be homogeneous and with equivalent mechanical properties. Modeling in this way is simple and the calculations is also very less than micro modeling.In fact, the stress-strain curve of the masonry wall and a conventional properties such as elasticity modulus and Poissons ratio of the masonry and etc will be able to model the nonlinear behavior of the masonry wall. The nonlinear static analysis is used for analysis of masonry wall. First, by comparing the result of numerical modeling with the experimental results, the correctness of the selected method for controlling the masonry infill is controlled and then the steel frames of a one story-one bay and two story-two bay with rigid saddle connection are modeled in the software. The interaction between the steel frame and masonry infill is modeled using contact elements with Mohr-coulomb behavior. Comparing the results of numerical simulations with experimental results, it shows that numerical model in three-dimensional simulation behavior of unreinforced masonry wall and rigid saddle connection has a good ability. In this thesis, In addition to modeling, increase percent of stiffness, increase percent of ultimate strength and the ductility changes of the composite frames relative to the empty frame with different yielding stresses and single masonry infills with different compressive strengths, the intensity stress distribution, the intensity elastic strain distribution composite frames and empty frame and the cracking pattern of masonry infill in the composite frames are also considered. Finally the results, is an increase in the stiffness and final strength and the ductility changes of the composite frames in comparison to the empty frame and single infill panel and the negative effects of the infill panel on the members of the perimeter frame caused by the interaction of the frames and infill panel.  

  Historic bridge bridges are of great artistic value for humanity, and their historical architecture reflects the cultural identity of peoples of that time. Over the centuries, these structures are still stable and serviceable at risk for natural hazards such as earthquakes, floods, fires, wars and the growing population of the world. The bridge studied in this study is the old bridge. This bridge is one of the national Iranian and archeological works of Kermanshah Province which is located on the eastern border of Kermanshah, located on the Gharasso River, as a way of communicating the villages of Faramans Drood in entering Kermanshah. The bridge was constructed in the Sassanid period and was rebuilt in the current Safavid period, with six spans, about 188 meters in length, 9 meters in height, and 8.6 meters in height, including the crown of the bridge. The foundations of this bridge are hexagonal, the inner part of which is made up of lime sandstone and lime sandstone, and is surrounded by rectangular cubic stone blocks. At the front of the stands, opposite to the flow of the droplets of the triangle is a shape.

بهسازي خاك هاي ماسه اي بوسيله ي رسوب ميكروبي كلسيت

<  gt;ارزيابي تاثير مقاوم سازي اتصالات تير -ستون با ورق FRP در پارامترهاي رفتار ديناميكي قابهاي بتن مسلح</P>

Progressive collapse is a phenomenon that a local damage results in failure of adjacent elements and finally results in global collapse of the structure or a large part of it. The main feature of this phenomenon is that global collapse is not proportional to initial failure. This type of failure, the first time in 1991 and during the 22-story building collapse Ronan Point in London, it attracted attention of engineers. It is clear that the phenomenon of progressive collapse, because of that occurs in a very short period and the imposition of non-linear transformations to elements before the rupture, has a nonlinear dynamic nature. Since 1990, numerous studies on the use of buckling restrained braces on improving the performance of Steel and Reinforced concrete frames has been done, but so far the effect of this type of braces on the progressive collapse of the reinforced concrete frames has not reviewed. In this thesis, a regular reinforced concrete structure designed in accordance with standard 2800 first edition and then the building has been under nonlinear static analysis. Because of the structure has not played to the level of performance, in accordance with the fourth edition of the standard 2800 and publication 360 Edition 1392 using braces Buckling Restrained, Chevron, V-shaped has been retrofitted. As well as a reinforced concrete structure in accordance with the Fourth Edition 2800 has been designed and in the end, the effect of progressive collapse in the outer frame of these structures, according to an alternative load path, using nonlinear dynamic analysis in OpenSees software has been investigated. The results show that the use of braces, not only improves the performance of the structure under lateral loads are reduced but the probability of occurrence of the phenomenon of progressive collapse in retrofitted reinforced concrete frames are reduced too and as well as the Buckling Restrained braces have better performance than the V-shaped braces and Chevron in the phenomenon of progressive collapse.

  Small strain shear modulus of the soil dynamic parameters in geotechnical science is the foundation design and liquefaction assessment and dynamic loadings and other issues play a major role.This parameter can be measured and calculated by field research experiments or in the laboratory using a borehole or bender elements or column resonance, etc…Factors affecting the shear modulus can be confining pressure, void ratio, the average grain size and shape and arrangement of the particles noted.In this study, the experimental approach using bender elements; the influence of grain size on shear wave velocity and therefore the shear modulus dry sandy soils under pressure from all sides at different frequencies investigated.The results indicate that the shear modulus is sensitive to changes in grain size, as in a range of dimensions with its increase, the shear modulus increases and decreases in other domains.The purpose of this factor, which is a measure of grain to the highest shear modulus in the range of their own. In general, sandstone samples tested for maximum shear modulus for the range is about 1 mm of dimensions.

  AbstractDue to the significant load carrying capacity of masonry wall, they were comprised the main construction materials in the past year. First, this materials were obtained by the hardening of mud on side of the grill and cooking ovens. Todays bricks were built based on this issue. At that time, it was used only because of its strength and availability, but with the passage of time and observing the behavior and performance of these materials in earthquakes and wind, the need to understand the exact behavior of these materials were felt more than ever.,Wood has been used since the beginning of history and due to its good tensile strength and economical and easy process there in its manufacturing and also help to protect the environment because of carbon dioxide that its stored in, is taken into consideration. Another advantage of wood are cheap cost and availability in the Cities and villages are underdeveloped.Masonry structure with timber framed is a structural system with high diversity and complexity. Limited analytical and experimental research has been done to detect seismic response on this structure. From the Bronze Age, this system was common in seismic areas. According to the behavior of masonry structures, the fundamental weakness of them against the earthquake, not lack of strength, But it is the lack of stiffness or plasticity. This weakness can be alleviated by reinforcement. Despite of the high shear strength of masonry structures, due to brittle behavior of materials, the improvement of performance of these structures for increasing in capacity and ductility is very important and the use of reinforcement elements such a member in order to eliminate disadvantages of these structures had historically been considered.

  Due to the development of appropriate methods for seismic retrofit and rehabilitation of buildings against seismic loads due to the vulnerability of masonry buildings that include a large number of buildings in the country is an important. One of the methods of retrofit and rehabilitation for unreinforced wall is use of steel bars with concrete coverage in one or both sides of wall. This steel gride is connected to the wall with steel nails. Implementing of such method increases the lateral loading capacity of wall, but also caused more cohesion of wall in integrity manner. In recent years, engineers implemented this method as an efficient and economical way for the most rehabilitation plans of the countries present masonry buildings. But since the lack of experimental information over these walls seismic performance and actions, which their designing generally based on the standards of concrete instructions or engineering judgment. According to the studies that have not been performed about the effect of steel nails in the reinforced wall. In this thsis first a pull-out test was carried out to place the steel rebar embedded in brick-mortar sample under tensile load. As the result of this test, bond strength, maximum tolerable tensile and displacement corresponding to the tensile load and load-displacement curve are obtained. Then, the experimental model was numerically simulated to obtain sliding, displacement, plastic strain, and the stress of the steel rebar and the brick-mortar sample. Second by using ANSYS17 software is investigated the effect arrengement of this steel nail on seismic performance of masonry walls with 10cm, 20cm, 30cm thickness in full-scale and small scale. The load – displacement diagram to one side wall on both sides of reinforced concrete with an experimental model has compared then the load – displacement diagram, displacement contour, and plastic strain for two side and one side reinforced wall in two forms with steel nails and without steel nails has compared. Finally, the steel nails force diagram is shown.