رضا آقایاری

Surrounding the central core of a concrete component by means of an internal or external factor such as transverse reinforcements, carbon and polymer fibers and steel sheets causes confinement for the concrete. Confining generally improves the strength and ductility of concrete components. As a result of boosting the local performance of elements, the overall performance of structure is made progress. Recently, tending to build irregular structures has been increasing. The presence of irregularity in the structure has always been one of the challenges faced by engineers.  In this investigation, the influence of confinement phenomenon on the seismic performance (damage level and behavior factor) of the moment resisting reinforced concrete frames with vertical irregularity is assessed. To do so, 31 moment resisting frames with vertical irregularity are categorized in four classes including 3-, 6-, 9- and 12-story and the roof displacement-base shear curves of them are acquired using pushover analysis. The capacity curve of each frame is achieved in two states including neglecting the confinement effect and considering it. The outcomes indicate that not only can confining improve the seismic performance of structures but also it can decrease the imposed damage of structures. In other words, comparing the capacity curves of each frame with/without confining effect shows that taking the confinement effect leads to improving the secant stiffness and strength of the frame. Furthermore, due to confinement effect, lateral load carrying capacities of the frames are boosted and the considered damage levels are achieved in higher base shear and roof displacements in comparison with the state that confinement is not considered. The observed values of damage levels indicate that the influence of confinement for higher frames is more significant and the maximum base shears for the frames with the confining action is around 3-19% higher than those of the frames without confinement effect. For 3-story frames, considering confinement effect leads to improving 3.9, 3.6 and 2.9% in damage levels of DL, SD, and NC. For 6-story frames these values are 6.9, 9.5, and 6.8% respectively. Taking confinement effect results in improving 18.25, 11.8, and 14.6% in damage levels of DL, SD, and NC and 14.3, 14.2, and 13.3% improvement for 12-story frames. Comparing the behavior factors in the two states demonstrates that considering confining effect improves the mean values of behavior factors around 10.4%. In addition, the observed values of behavior factors show that the differences between the amounts of behavior factors (with/without confinement effect) for the frames with more stories are higher. It is manifested that type of irregularity plays significant role on the seismic behavior of the moment-resisting reinforced concrete frames. Comparing the analytical behavior factor obtained in the current study with the prescribed value of behavior factor in Iranian seismic code shows that although the proposed value of Iranian seismic code is conservative for low-rise frames, this value is not met for high-rise frames.

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 Standard 2800, the incremental spectral correction coefficient (N) was introduced. In this paper, the accuracy and estimation of the value of this coefficient for five 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 seven far-field records, and 22 near-field records) is calculated, and then by 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 Standard 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 Standard 2800. This difference has reached 58% in some structures. It was also observed that there is no regular relationship between the 1st period of the structures and the magnitude of the spectral correction coefficient and the magnitude of the spectrum correction decreases with increasing seismic intensity.

Determining the pattern of lateral displacement distribution in the height of structures and the factors affecting it, has an important role in increasing the accuracy of optimal design and functional design against various seismic loads. In this paper, the pattern of lateral displacement distribution between floors at the height of flexural reinforced concrete frames is investigated and the effect of seismic intensity and pulse period on this issue is investigated. The studied frames are three structures of 3, 9 and 15 floors of RC Moment-resisting frames. the middle frames of the structures were non-linearly modeled in 2D in the SeismoStruct 2021 program, and nonlinear analysis was performed under the set of records and at different seismic intensities. the displacement response of the structures was compared. The results showed that in orderly short-term reinforced concrete bending frames without any irregularity under the set of selected accelerometers in this research, the effect of all records is almost equal and displacement occurs in the upper floors. As the height of the structures increases and the effect of higher modes increases, the effect of the pulse period of stagnation and seismic intensity is felt.

The moment-resisting steel frame building is highly used due to their advantages such as, high speed construction coupled with appropriate strength and ductility. The main advantage of this system is related to architectural considerations and the possibility of creating openings within all spans. Connections play an outstanding role in the seismic responses of this structural system. The connections are generally assumed to have a rigid behavior in analyzing and designing of the moment-resisting steel buildings. Studying of the previous investigations indicates that the assumption of rigid behavior for the beam-to-column connections is not always correct and can bring about a significant error in the responses. In this study, behavior factor of moment-resisting steel frames considering joint flexibility is evaluated. To do so, some intermediate moment-resisting steel frames with various number of stories and bays including 1-bay, 1- and 2-story frames, 2-bay, 2-, 4-, 6-, 8-, and 10-story frames, 3-bay, 3-, 6-, 9-, and 12-story frames and 4-story, 2-, 6-, 10-, and 14-story frames are designed regarding Iranian seismic code and Iranian national building code for designing steel structures. After that, the capacity curves of these frames are achieved using pushover analysis once considering rigid connections and again taking joint flexibility into consideration using OpenSees software. To model the nonlinear behavior of connections, one zero-length rotational spring is assigned to each end of beam members. Then, the behavior factor of each frame is calculated using the recommended procedure of FEMA-P695. The outcomes show that for the frames with rigid connections, the acquired behavior factors are almost close to 5 (which is the prescribed behavior factor in Iranian seismic code for the intermediate moment-resisting steel frames). Furthermore, for the frames with semi-rigid connections (60%), the behavior factors are close to 5 as well. For 10-story 2-bay, 12-story 3-bay, and 14-story 4-bay frames the prescribed behavior factor in Iranian seismic code does not meet. For these frames, the ratio of height to total-span that is known as the slenderness coefficient of the frame is higher than others, so these frames fall into slender frames. Results show that for the frames with semi-rigid connections (60%), despite of decreasing the over-strength factors in some cases, their ductility increased, therefore, the behavior factors are achieved higher than those of the frames with rigid connections. All in all, it is observed that the nonlinear behavior of connections can significantly affect the seismic behavior of the moment-resisting steel frames. Comparing the behavior factors calculated in this investigation with the prescribed value of this factor in code 2800 showed that for the frames with rigid connections, 80% of the obtained behavior factors are higher than 5. For frames with semi-rigid connections (80% and 60%), 0%, and 66% of the behavior factors meet the proposed value of code 2800, respectively. Regarding the observations, it is recommended that the influence of joint flexibility be considered in assigning a value of behavior factor to design the moment-resisting steel frames.

Tuned mass dampers (TMDs) are being increasingly used for protection of structures against seismic and environmental loads. An important step in design and application of TMDs is the evaluation of TMD parameter which can cause be associated with serious difficulties. In this paper, we attempt to provide a framework to evaluate the modal parameters of TMDs using a combination of experimental test on shake table and a relatively recent modal analysis technique, namely Frequency Domain Decomposition (FDD). In order to achieve this, a series of test were conducted on a 5-storey steel frame was subjected to excitations from two scaled earthquakes (Imperial Valley and Kobe) ) while damped using two TMDs with mass ratios of 0.01 and 0.1.Mounted instrumentations recorded the structural response during the earthquakes and the recorded response was then used for an operational modal analysis (OMA) in order to estimate the dynamic characteristics of the TMDs. The FDD technique was used in this paper which was employed to estimate the parameters of TMDs. The damping ratios obtained from FDD method was compared with classical methods to verify its accuracy and capabilities in extraction of the modal parameters of TMDs. This paper shows that the use of shake table experiments coupled with the post-experiment modal analysis can be successfully used in TMD design and enables the researchers and practitioners to accurately estimate and test the response of the structures under relatively realistic conditions, which consequently allows low-cost testing of TMDs for optimum TMD selection.

Cyanide is a by-product of various industrial chemical processes found in industrial effluents which must be treated before it is discharged into the environment. Industrial effluents containing cyanide is treated through different methods including physical, chemical and biological processes which are often too expensive.The aim of this study is to evaluate the application of Artificial Neural Network (ANN) in predicting the removal efficiency of cyanide ions from aqueous solutions by Zno@MOF-199 nano-adsorbent. The research data was collected based on laboratorial study of important parameters involved in the Levenberg-Marquardt Back-propagation Artificial Neural Network Model (BP-LM) for prediction of cyanide removal efficiency including pH range from 5 to 9, contact time of 30 to 90 minutes and temperature range from 25 to 45 ºC. Parameters such as pH, temperature, contact time, adsorbent weight and sample volume were considered as input and cyanide removal efficiency as output data. In the comparison of different models, statistical criteria of correlation coefficient and sum of squared errors (SSE) were applied. The obtained results, 0.985 for the correlation coefficient and 0.65 for the sum of squared errors, indicate a successful prediction of the network in modeling as well as the efficiency of neural network in predicting the removal efficiency of cyanide ions from the solution.

in Persian literature, traveling has been proposed in the poems. The spiritual dimension which is known as the internal, spiritual, and inner traveling desire has been originated from the thoughtfulness principal of mystic literature. This journey’s destination is God which finally ends up with decay in God is known as a type of rebirth of the faithful follower (called survival after death). All efforts of the mystics revolve around the guidance of human being to this route. If we investigate the thoughts of the mystics during the pass of centuries, we can come across a thought bond within this relationship. Each poet has emphasized about inner journey in a different way but referring to the same concept. In the present research the thoughts of two great figures in mysticism, Sanaee and Molavi, about traveling . The results showed that both poets have understood their mystic responsibility in a way that they considered themselves responsible to guide human beings to enter the route to know their divine identities. Therefore, they have stressed on inner journey. The obligatory journey of human being has exiled him/her from the divine world into this world and human beings should try to re-enter that world through inner journey. To do so, human being should abandon worldly pleasures and should enter mystic routes with the help of a leader. Regarding this view, we can refer to the ancient pattern of heroic journey to the mystic world

The tunnel form buildings provide some advantages for medium to high-rise buildings that constructed by using a special tunnel form technique are commonly built in countries facing a substantial seismic risk. There are no special requirements for seismic design of this type of buildings, and some provisions of the concrete bearing wall system are used. None of the seismic codes addresses the R factor for tunnel‐form buildings directly. This study presents R factor of this structural system based on the nonlinear pushover analyses of 7 case studies using the ABAQUS software. The impacts of shear wall reinforcement ratio and its detailing on system ductility, load-carrying capacity and failure mechanism under seismic forces are evaluated. Influences aspect ratio and wall openings on the response are also discussed.

The demand for FRP materials has been increased over the past years for retrofitting or strengthening of reinforced concrete members. Several recent studies focused on the shear strengthening of reinforced concrete deep beams. In deep beams, due to the high ratio of shear span-to-depth and shear deformation, the ultimate strength is generally controlled by shear rather than flexure with lower shear ductility. Shear strengthening with FRP sheets is one of the most effective methods to overcome the weaknesses of deep beams.
In this paper, the behavior of 104 deep beam specimens strengthened with different schemas of FRP sheets which was investigated. Specimens were modelled through the Non Linear finite elements method and analyzed under Push over static loading. The efficiency of FRP installing schema and the effect of some parameters such as shear span-to-depth ratio, compressive strength of concrete and the arrangement and ratio of shear reinforcement were evaluated. The results showed an average increase of shear capacity varied between 15 through 65 percent in each schemas of installed FRP sheets.
Another aim of this study is to define and evaluation of shear ductility index for deep beams. The results show that the shear ductility index depends on the dimensions of the deep beam, compressive strength of concrete and the scheme of installed FRP sheet as using the layers of FRP can increase the shear ductility of strengthened deep beams about 5 to 30 percent.

Due to the growing popularity of concrete structure and increasing use of them, especially Roller compacted concrete, applying Pozzolan and replacing cement with Pozzolan is very important. Nowadays, the use of the additive for cement replacement is common in RCC mix design due to its technical advantages and economic benefits as there is large quantity of Pozzolan mineral resources in Iran. In this paper the impact of produced concrete has been fully considered as well as the effect of this Pozzolan on the compressive strength, tensile strength and permeability by using green Tuff obtained from available Pozzolan in western Azarbaijan. The due results prove that Shahin-Dezh green Tuff improves concretes quality.

Reinforced concrete deep beams have useful applications in many structures, such as tall buildings, foundations, offshore structures, and several others. The reinforced concrete deep as important structural elements having small span-to-depth ratio. The investigation of their behavior is a subject of considerable interest in RC structures researches and some studies on the shear strength of reinforced concrete deep beams have been carried out over the last fifty years. In deep beams, according to shear span-to-depth ratio and web reinforcement the ultimate strength is generally controlled by shear rather than flexure, if the sufficient amount of longitudinal reinforcement is used. Several different failure modes have been identified from experimental studies, due to variability in failure, the determination of their shear strength and identification of failure mechanism are very complicated. In this paper the influence of effective parameters on the behavior of high-strength RC deep beams was investigated. For this purpose, an experimental-analytical investigation was conducted; a total of five reinforced concrete deep beams with compressive strength in range of 60 MPa were tested under uniform contributed top loading. The tested specimens were simply supported and reinforced by vertical steel bars in various spacing. The general behavior of tested beams was investigated. Observations were made on mid-span vertical deflections, cracks form, failure modes and shear strengths. All the beam specimens showed a same response up to failure. The test results indicated that vertical web reinforcement are efficient in shear capacity of deep beams, all the specimens were failed at abrupt shear mode. According to the test results, the shear capacity is affected by amount of web reinforcement and the test specimens are stronger in comparison with those were tested under two-point loading. Elastic solutions of reinforced concrete deep beams provide a good description of the behavior before cracking, but after cracking, a major redistribution of stresses occurs and hence the beam capacity must be predicted by inelastic analysis. Due to their geometric proportions, the capacity of reinforced concrete deep beams is governed mainly by shear strength. Deep beams behave differently from shallow beams and have been identified as discontinuity regions where the strain distribution is significantly nonlinear and specific strut-and-tie models need to be developed, whereas shallow beams are characterized by linear strain distribution and most of the applied load is transferred through a fairly uniform diagonal compression field. Strut-and-tie method is one of the most simple and applicable methods which can be used to simplify analysis and design of deep beams. Strut-and-tie modeling is the most rational and simple method for designing no flexural members currently available. At least, the experimental strength of specimens was compared with predicted results of strut-and-tie method (STM). The performed comparison indicates that the STM to provide acceptable estimates of shear capacity of deep beam loaded under uniform loading.

Many flat slab -column frame structures have been built in many parts of the world، since the beginning of the century. The absence of beams makes the form work simple، increase the clear story height، and decreases total building height. However brittle punching failure is a problem that unnecessarily limits the widespread use of flat plates in active earthquake zones. Many slab -column connections in flat plate structures were damaged and failed in punching shear after the 1985 Mexico City earthquake، the 1989 Loma Prieta earthquake، and the 1994 Northridge earthquake. These shows that slab–column connections are prone to punching shear failure when lateral forces، due to earthquake loading، cause substantial unbalanced moments to be transferred from the slab to the column. Slabs with low or medium reinforcement ratios tend to fail in flexure rather than in punching shear. For slabs with reinforcement ratios of 1% and more، the mode of failure tends to be the punching shear type of failure. Fiber-Reinforced Polymers (FRPs) have gained increasing popularity in retrofit of reinforced concrete members in the last two decades. Using FRP materials to enhance slabs in flexure is very desirable from the application point of view due to the ease of handling and installing. FRP material، unlike steel، are not subject to either corrosion or rust in the long term. There is limited amount of research available on srengthening of slab connections. These studies include investigations where the slabs were strengthened using FRP laminates around a central stub column or bonded over the entire width of the slab. with regard to flexural strengthening، externally bonded FRP strips have been used for the strengthening of one way slabs as well as two way slabs. The determination of the structural behavior of FRP–strengthened concrete slabs requires extensive experimental and/or advanced numerical methods. as far as theoretical methods are concerned، Reitman and Yankelevsky have developed a nonlinear finite element grid analysis based on the yield line theory. Other researchers have employed finite element packages to investigate the structural behavior of strengthened slabs with FRP that a full bond between the concrete and the adjacent strengthening FRP materials was assumed. Recently، Binici and Bayrak reported the test results of a strengthening method using carbon fiber reinforced polymers (CFRPs) as shear reinforcement. Previous studies concentrated on enhancing shear capacity of slab-column connections for new construction. Stirrups، bent up bars and shear studs were used as shear reinforcement in previous studies. This study investigates the application of different methods of strengtheing of flat slabs. At first، slabs were model in ABAQUS in order to study the parameters that influences punching shear capacity. Analytical result indicate that increasing concrete compressive strength improves punching shear capacity. Based on this result، steel reinforcement ratios determines the mode of failure. Then، FEM models of slab were strengthend، and type of strengthening، type of FRP materials، number of strip and layer were investigated. The results show that using FRP strip increases punching shear capacity and reduces energy absorption.