فهرست مطالب

Advanced Structural Engineering - Volume:13 Issue: 2, Summer 2023

International Journal of Advanced Structural Engineering
Volume:13 Issue: 2, Summer 2023

  • تاریخ انتشار: 1402/05/23
  • تعداد عناوین: 6
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  • Mehri Asgari *, Mohammadreza Adibramezani Page 1

    In this study, the pre-approved connection and the proposed connection have been investigated and analyzed using Abaqus finite element software. Non-linear static analysis was performed with reciprocating loading. In this study, in order to compare the proposed connection and the direct connection, two one-story and six-story frames has been modeled and the behavior of the two connections in these frames has been investigated. According to the software models, it can be seen that in all the models, the bending moment capacity of the connection is more than 40% of the calculated plastic moment in the connection. In connection with the reduced cross-section, this percentage has reached nearly 20%. The results of the proposed connection behavior show that it performs nearly 25-34% better than the pre-validated connection of the 10th topic of Iran regulation of structures. The structure with the proposed connection has a higher coefficient of behavior than direct connection. With the increase in the height of the structure, the coefficient of behavior of the structure has also decreased.

    Keywords: Steel Connection, Abaqus Finite Element Software, 2800 Standard, Nonlinear Static Analysis Of Time History
  • Mehdi Shahraki *, Abolfazl Miri Page 2

    Masonry arches stand out as some of the most valuable, significant, and defining components of traditional Iranian architecture. These structures have been admired throughout history for their aesthetic appeal and structural resilience, earning recognition as masterpieces of architecture and civil engineering both in Iran and globally. The Mount Khajeh archaeological site, which includes the ancient Mount Khajeh Palace and Kafro Castle from the Parthian-Sassanid era, is located in the Mount Khajeh rural district, Hamoun County, Sistan and Baluchistan Province. The arches at this historical site represent some of the most essential and treasured elements of traditional Iranian structural design. However, no prior research has been conducted to assess the seismic impacts on these arches or to propose methods for their retrofitting. This study aimed to address this gap by first developing a general model in ABAQUS to analyze the overall behavior of a representative arch. The most critical section of the arch was then isolated and modeled as a sub-representative of the entire structure. Using a simplified micro-level approach, both frictional and cohesive behaviors were incorporated at the block-mortar interfaces. Time-history dynamic analysis was performed on the selected arch using acceleration records from significant global earthquakes and one event recorded in Iran. These records were sourced from the Pacific Earthquake Engineering Research (PEER) Center's database. The findings reveal that, in terms of energy absorption, displacement, ductility, response modification factor, and maximum base shear, the first arch model demonstrates superior seismic resistance compared to two other arch models. Additionally, the results show that modeling and analyzing the arch in both its retrofitted and unstrengthen states significantly enhance its lateral load resistance, improve its seismic performance, and refine the crack distribution pattern. Furthermore, the application of the NSM-FRP strengthening technique minimizes damage and preserves the original appearance of the arch.

    Keywords: Arch, Mount Khajeh, Retrofitting, FRP Rebar, Sarpol-E Zahab
  • Mohammad Khodaparasti, Ali Alijamaat, Majid Pouraminian * Page 3

    Assessing the seismic vulnerability of existing buildings is one of the major concerns of governments in the world. Reducing the destructive and catastrophic consequences of earthquakes is necessary and inevitable. So far, various techniques have been presented to evaluate the seismic vulnerability of buildings. One of the fast and effective assessment techniques is the Rapid Visual Screening (RVS) technique with fastly identify high-risk buildings for a more accurate assessment. Among the RVS methods, the Hassan-Sozen PI method is the simplest method to evaluate the seismic vulnerability of low-rise RC buildings. The value of the priority index (PI) is determined from the simple geometric features of the building such as the number of stories, floors area, column area, area of concrete walls and infilled in the main directions of the building. In this article, the data collection have been gathered from Elyasi et al.'s reference such as geometrical information (with geometrical features provided by Hassan-Sozen) and earthquake features (peak ground acceleration and earthquake magnitude) for 658 low-rise RC buildings. The number of considered input features includes seven geometric features and two earthquake features (9 features in total) and the predicted output of Hassan-Sozen priority index. The machine learning technique utilized in this article for prediction seismic vulnerability is a probabilities random forest in which a simple Bayesian method is used to create forest trees. This method has had a slight improvement in accuracy criteria and considerable improvement in accuracy and recall criteria compared to other traditional random forest and ML methods.

    Keywords: Seismic Vulnerability, Rapid Visual Screening, Machine Learning (ML), Random Forest (RF), Simple Bayesian, Reinforced Concrete Buildings
  • Payam Tarighi * Page 4

    Tension control bolts (TC bolts) are specialized fasteners mainly utilized in steel frame construction. They include a pre-assembled bolt, nut, and washer for simplified installation. In contrast to standard bolts, TC bolts have a domed head and a distinctive spline design that enables accurate tensioning during the installation process. This advancement has led to their growing popularity in the construction sector because of their effectiveness and dependability. In this article, examined this type of bolts, installation mechanism, their advantages over conventional high-strength structural bolts, challenges and considerations, durability comparison between traditional and TC bolts, design features, installation process, and also review the relevant standards associated with them.
     ension control bolts (TC bolts) are specialized fasteners mainly utilized in steel frame construction. They include a pre-assembled bolt, nut, and washer for simplified installation. In contrast to standard bolts, TC bolts have a domed head and a distinctive spline

    Keywords: Tension Control Bolts, TC Bolts, High-Strength Bolts
  • Mehdi Firoozbakht, Aliakbar Edalati * Page 5

    Bridges are vital to modern transportation infrastructure, providing convenient and efficient access to different locations. Because of their structural simplicity and low degree of indeterminacy, bridges tend to be particularly vulnerable to damage and even collapse when subjected to earthquakes. The costs of their construction and retrofitting are high, so the maintenance of these capitals is one of the necessities of urban management. This paper investigates the influence of increasing the height of bridge piers on seismic behavior of isolation systems in urban reinforce concrete (RC) bridge. For this purpose, the seismic performance of the Hesarak Bridge constructed in Karaj city, Iran with two isolation systems; i.e. the existing elastomeric rubber bearing (ERB) and a proposed lead rubber bearing (LRB) are discussed by changing three times the height the bridge piers as compared with the existing situation. The numerical model was implemented in the well-known FEM software CSiBridge. The isolated bridge has been analyzed using nonlinear time history analysis (NTHA) method with seven pairs of earthquake records and the results are compared for the two isolation systems in both height modes. The results showed that with the increase in the height of the bridge piers, the natural period of the LRB isolated system changes from 2.7 to 2.77 seconds and on the other hand, this value increases from 1.37 to 1.62 in the ERB isolated system. The ratio of maximum base shear force for the bridge with the LRB to the ERB isolators under given ground motions in longitudinal and transverse directions showed higher values with increasing the height of bridge piers in comparison with the current situation, which indicates the weaker seismic performance of LRB isolators. Also, the results of the numerical Analysis illustrate the pier head relative displacement of columns increases in the longitudinal direction of the bridge with increasing height of bridge piers.

    Keywords: Bridge, Keywords: RC, ERB, LRB, NTHA
  • Ehsanollah Zeighami *, Mohsen Ghomi, Mohammad Mirhosseini, S Lajevardi Page 6

    Concrete is highly vulnerable to tensile stress, and the use of rebar is not always practical or cost-effective. Forta Ferro fibers offer an alternative solution for enhancing the tensile strength of concrete. In this study, 36 cylindrical and 36 cubic samples were tested using compressive strength, Barcelona, and double punch tests. The samples were aged for 28 days and contained 0, 1, 2, or 3 kg/m3 of Forta Ferro fibers.
    The results showed that adding 1 to 3 kg/m3 of Forta Ferro fibers to the concrete increased the 28-day tensile strength (BCN test) by 8.40% to 9.04% in cylindrical samples and 8.71% to 8.93% in cubic samples. Similarly, the 28-day tensile strength (DPT) increased by 6.81% to 9.42% in cylindrical specimens and 3.92% to 6.69% in cubic specimens when Forta Ferro fibers were added.
    The proposed Chen coefficient of 1.08 is suggested as the correction factor for the Forta Ferro fibers.

    Keywords: Concrete Tensile Strength, Forta Ferro Fiber, Barcelona Test, Double Punch Test