فهرست مطالب

Advanced Structural Engineering - Volume:13 Issue: 1, Spring 2023

International Journal of Advanced Structural Engineering
Volume:13 Issue: 1, Spring 2023

  • تاریخ انتشار: 1401/12/20
  • تعداد عناوین: 6
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  • Saeed Samadzadeh Baghbani, Farivar Fazelpour*, Hossein Ahmadi-Danesh-Ashtiani Page 1

    Nowadays, the use of phase change materials is very important to reduce energy consumption in buildings and industry structures. The use of phase change materials in the structure of buildings will be widely used in the near future. Because the presence of these materials in the building structure, such as the use in water heater cultures, will reduce the consumption of fossil energy.Phase change materials (PCM) store thermal energy in the latent heat method. These materials have a high thermal storage density and with small temperature changes, they provide an important role in saving energy and thermal insulation in the building. Materials naturally delay the transfer of heat to the building by several hours due to the reduction of indoor air temperature fluctuations and the room air temperature remaining close to the desired room temperature for a longer period of time. In order to recover heat or cold, the storage method is used. In general, there are two types of thermal energy storage systems during physical processes:1- Storage of sensible thermal energy ,2- Latent thermal energy storage. In this article, we investigated the use of phase change materials in the solar collector installed in the building. In this article, Ansys Fluent software is used for simulation. The amount of solar radiation in Iran is estimated between 1800 and 2200 kilowatt hours per square meter per year, which is higher than the world average.

    Keywords: Renewable Energy, Phase Change Materials, Ansys Fluent, Buildings, Structure
  • Ali Moradi, Ehsan Delavari*, Mohsen Saadat, Shamsa Basirat Page 2

    In this paper, the vertical displacement of a non-homogenous embankment dam is investigated and evaluated in both static and dynamic states using FLAC software. In this regard, initially, the results obtained from this software are validated against the results of conventional methods. Subsequently, using FLAC software and 100 selected models, the impact of important dam parameters such as crest and core height on the vertical displacement of the dam is studied under various conditions in both static and dynamic states. The data analysis approach in this work involves considering a parameter as a witness. The witness parameter remains constant, and assuming that it does not participate in the analysis, one effective parameter and one criterion parameter are chosen for discussion and examination. For example, if the dam base is chosen as the witness parameter, and its value is intended to be 165 meters, the results have shown that an increase in the height of the earth dam leads to an increase in vertical displacements under static and dynamic loadings.

    Keywords: Static Analysis, Dynamic Analysis, FLAC, Non-Homogenous Embankment Dam
  • Pooya Arezoomand Langarudi, Mohammadreza Adibramezani*, Ata Hojatkashani, Saeedfarokhizadeh Page 3

    Evaluating the seismic vulnerability and collapse capacity of structural systems typically involves conducting Incremental Dynamic Analysis (IDA) and generating fragility curves, both of which are complex and time-consuming. To simplify the extraction of fragility curves at different performance levels, the SPO2FRAG software was developed by previous researchers. However, its accuracy in predicting the collapse capacity of systems with varying heights has not been thoroughly validated against detailed analyses using seismic records. This study evaluates the efficiency and accuracy of SPO2FRAG in steel plate shear wall systems (SPSWs) with 4, 8, 12, and 16 stories, all designed in accordance with relevant codes. The numerical models were validated against a well-documented experimental specimen to ensure reliability. Fragility curves at the collapse performance level were derived using two

    methods

    (1) IDA with 22 pairs of far-field earthquake records, and (2) the SPO2FRAG software he results show that for 4- and 8-story buildings, SPO2FRAG provides conservative estimates of collapse capacity compared to the more precise IDA. However, its reliability decreases with building height, leading to significant overestimation in the 16-story structure. While SPO2FRAG is a quick and cost-effective tool for assessing low- to mid-rise SPSWs, more accurate methods like IDA are recommended for taller structures. This study highlights the limitations of SPO2FRAG in evaluating taller SPSWs and underscores the importance of using detailed analysis methods for critical infrastructure. Future research should focus on enhancing the predictive capabilities of simplified tools like SPO2FRAG for high-rise structures.

    Keywords: Steel Plate Shear Wall, Pushover Analysis, Fragility Curve, Incremental Dynamic Analysis, Performance-Based Assessment
  • Mehdi Firoozbakht, Hamidreza Vosoughifar *, Alireza Ghari Ghoran Page 4

    Adequate selection of sensors placement plays a key role in structural health monitoring (SHM) in base isolated (BI) structures. This critical issue is usually done by past experience and knowledge on the force and vibration situations of a structure. During recent decades, techniques have received increasing attention as a tool for determining an arrangement of sensors suitable for SHM. In this paper, a multi- objective numerical method for optimal sensor placement (OSP) in BI structures based on the combination of traditional OSP algorithms and nonlinear time-history analysis (NTH) has been proposed. Next, genetic algorithm (GA) was employed to determine the location of sensors on the structure based on the structural dynamic response of the BI system. To show the efficiency of the proposed method, a BI building was modeled using finite element method (FEM) in which NTH were undertaken using the seismic scaled records of near-fault earthquakes (NF). The novel numerical approach called transformed time history to frequency domain (TTFD) was evaluated to transform NTH results to frequency domain and then the effective frequencies according the maximum range of Fourier amplitude were selected. The modified type of modal assurance criteria (MAC) values can be achieved from MAC with the exact seismic displacement. Results show that the proposed method can provide the optimal sensor locations and remarkably reduce the number of required sensors and also improve their optimum location.

    Keywords: Structural Health Monitoring (SHM), Optimal Sensor Placement (OSP), Base Isolated (BI) Structures, Nonlinear Time-History Analysis (NTH)
  • Hossein Nematian Jelodar, Ata Hojatkashani*, Rahmat Madandoust, Abbas Akbarpour, Seyed Azim Hosseini Pages 607-615

    Concrete structures may be exposed to high heat. In such a way that high heat in the vicinity of concrete structures causes damage in concrete. The aim of this study is assessment of effect of electric high heat on the bending capacity, energy absorption, fracture type and crack distribution of circular fiber concrete slab under monotonic loading. The concrete aggregates with a fracture percentage of 45% are from the mines around Tehran and the fibers used in the concrete are of macrosynthetic type. The concrete mixing design was based on the target compressive strength of 45 MPa and the amount of fibers equal to 0.5% of concrete volume. The heating of the concrete samples was done by a 2400-liter device with a power of 90 KW and maximum temperature of 550 degrees Celsius. To perform slab tests, Dartec9600 device was used with monotonic loading at a rate 0.004 mm/s. based on the Experimental studies conducted on the fiber concrete slab, the application of high heat did not cause concrete peeling but it reduced the capacity of the slab by 89.3% and decreased the energy absorption of the slab compared to the control sample. Also, SEM photos have shown the aggressive destruction of macrosynthetic fibers and the creation of cracks under the effect of high heat in fiber concrete.

    Keywords: Energy Absorption, Concrete Slab, Macrosynthetic Fiber, Electric Heat, Bending Capacity
  • Mehdi Shalchi Tousi, * Samane Laali Pages 645-662

    This paper presents an economical optimization for cost and weight of reinforcement cantilever concrete retaining walls using Cuckoo Optimization Algorithm (COA). The proposed optimization algorithm is inspired from the life of a bird family called cuckoo. The capability of this algorithm is compared with other optimization methods available in the literature including ant colony optimization (ACO), bacterial foraging optimization algorithm (BFOA), particle swarm optimization (PSO), accelerated particle swarm optimization (APSO), firefly algorithm (FA), and cuckoo search (CS). A computer program has been developed by using the COA method for optimizing retaining walls. Five types of retaining walls were considered and sensitivity analyses were performed to find out the role of important parameters such including stem height, surcharge, backfill slope, and backfill unit weight and friction angle. Also, Coulomb and Rankine methods are used to estimate lateral earth pressures. The results show that the COA can minimize retaining walls from both cost and weight viewpoints. In addition, the COA can achieve to better results than ACO, BFOA, PSO, APSO, FA, and CS. The performed sensitivity analysis illustrates that with increasing surcharge and stem height, the cost and weight of wall increase. Also, the cost and weight objective functions decrease with increasing the soil unit weight. In addition, the Coulomb method gives lower cost and weight quantities than the Rankine method.

    Keywords: Sensitivity Analysis, Retaining Walls Optimization, Cuckoo Optimization Algorithm, Objective Function, Optimum Design