Somayeh Mollaei | University of Bonab (original) (raw)

Papers by Somayeh Mollaei

Advances in civil and architectural engineering, Mar 14, 2024

DOAJ (DOAJ: Directory of Open Access Journals), Jul 31, 2022

Građevinski materijali i konstrukcije, 2024

3D-Printed Concrete (3DPC) can reduce the consumption of materials, construction costs, and imple... more 3D-Printed Concrete (3DPC) can reduce the consumption of materials, construction costs, and implementation time, as well as increase sustainability. Seismic safety is one of the necessities of any structure in a high earthquake hazard zone. The lack of scientific and engineering studies in this area would highlight the importance of studying seismic safety in 3DPC building structures. This paper is focused on the basic specifications of 3DPC buildings under earthquake excitations. The authors conducted a thorough theoretical study due to the pilot nature of the research. A prescriptive evaluation was conducted based on the existing seismic regulations for similar structures. The main goal of the research was to create the necessary platform for applied studies, which was achieved through theoretical investigations and prescriptive evaluations. For this purpose, the finite element modeling of a 3DPC building with an arch roofing system was implemented and analyzed using ABAQUS software. Based on the main results, the most remarkable weakness of such a structure was the material's poor tension behavior. The arrangement of the internal partitions (infill walls), the shear performance of the walls, and the relative displacement of the components were other effective factors of the 3DPC building under seismic loads. The results showed that the truss-like performance of the arch roof in the considered 3DPC building probably caused the undesirable structural responses under the seismic loads.

International Journal of Sustainable Construction Engineering and Technology, Feb 14, 2023

Carbon dioxide emission and consumption of large amounts of natural resources are the environment... more Carbon dioxide emission and consumption of large amounts of natural resources are the environmental hazards observed in the production process of various commonly used construction materials, like Portland cement and clay bricks. Also, debris from the demolition of old buildings and disposing of the waste of construction material factories also cause environmental pollution. Producing environmentally friendly geopolymer materials with recycling construction wastes containing aluminosilicate resources and alkaline activators could be an effective method for reduction of environmental hazards. This paper is an innovative feasibility study of geopolymer material production using the waste autoclaved aerated concrete (AAC) powder. Here, a mix of AAC powder together with activator solution containing sodium hydroxide and sodium silicate at different concentrations was used to prepare the geopolymer mortar samples. The specimens were oven-cured at different temperatures. The effects of sodium hydroxide concentration and curing temperature on the compressive, tensile, and flexural strengths, as well as water absorption of the samples, were investigated. The main contribution of this study is the feasibility of the successful fabrication of geopolymer material based on AAC waste powder with desirable mechanical properties. Namely, the compressive strength of the base AAC blocks used here was 3 MPa and the maximum strength of the produced geopolymer material using the AAC powder was about 21 MPa. The test results were used to develop a model to predict the compressive strength of the proposed geopolymer AAC material to the effective parameters by Gene Expression Programming. The model predictions were confirmed using an extra series of test results implemented by the authors.

Proceedings of the Institution of Civil Engineers - Forensic Engineering

Seismic isolation is an efficient method for improving the seismic behaviour of building structur... more Seismic isolation is an efficient method for improving the seismic behaviour of building structures. Sensitivity analysis of the behaviour of base-isolated structures is essential for investigating the effects of various mechanical and environmental factors on the performance of seismic isolation systems. In this study, the optimal design of a lead-rubber-bearing seismic isolation system was investigated by considering irregular mass conditions and near-fault seismic excitation. The grasshopper optimisation algorithm was used to optimise the design of the isolation system. Sensitivity analysis of the seismic response of the isolated structures was carried out for the mechanical parameters of the isolation system, mass irregularity in the building and near-fault earthquakes. The results proved the efficiency of the algorithm in optimal design problems for structural isolation systems. Also, the sensitivity analysis of the seismic behaviour of base-isolated structures showed that the ...

International Journal of Engineering

Various mechanical and geometrical parameters have different effects on the isolation system's pe... more Various mechanical and geometrical parameters have different effects on the isolation system's performance. Thus, a sensitivity study of the isolated structures' behavior is an essential matter. In this regard, the isolation systems should be designed using optimization approaches to consider the effects of the different factors. In this study, the optimal design of the lead rubber bearing (LRB) seismic isolation was conducted by considering mass irregularity and near-fault seismic excitation effects. Also, sensitivity analysis of the behavior of the considered isolated buildings was implemented concerning the mechanical parameters of the LRB system. A nonlinear time history dynamic analysis was used here, and the design optimization of the LRB isolator was programmed using the newly introduced grasshopper optimization algorithm (GOA). The main purpose was to investigate the ability of the GOA to optimize the design parameters of the LRB-isolated frames. The results proved the desirable ability of the GOA to solve optimal design problems for isolation systems. Also, the sensitivity analysis of the seismic behavior of LRB base-isolated structures showed that the yield base shear index had the most important effects. Also, the mass irregularity parameter showed a negligible influence.

Seismic fragility curves are used to assess the probability of vulnerability of structures at var... more Seismic fragility curves are used to assess the probability of vulnerability of structures at various damage states. This research deals with the effects of different isolation systems on the seismic safety of a two-dimensional reinforced concrete moment-resisting frame. The reference structure was a hotel building in California. A comparative probability-based seismic safety of building components was investigated on the superstructure hypothetically fitted with various isolation systems. In this regard, two categories of isolation systems including, rubber-based and friction‐based were selected here. The High Damping Rubber Bearings and Friction Pendulum Systems were considered here. Incremental Dynamic Analyses were carried out for a suite of earthquake records to develop the fragility curves considering modeling, demand, and capacity uncertainties. Based on the main results, the influence of seismic isolation systems on the reduction of failure probability of building rather tha...

Archive of Applied Mechanics

Applied Sciences

Autoclaved aerated concrete (AAC) blocks have widespread popularity in the construction industry.... more Autoclaved aerated concrete (AAC) blocks have widespread popularity in the construction industry. In addition to lightness, these materials have other advantages, including fire resistance, low acoustic and thermal conductivity, ease of cutting and grooving, and simple transportation. Since the behavior of AAC under severe dynamic loading conditions such as blast loads has not been adequately studied in the literature, in the current paper, the behavior of masonry walls constructed with AAC blocks was evaluated under blast loading. In this study, after performing experimental testing on materials and obtaining their compressive, tensile, and shear strength values, the finite element (FE) models of AAC-based masonry walls were created in the ABAQUS/Explicit nonlinear platform. Three different wall thicknesses of 15, 20, and 25 cm were simulated, and the models were analyzed under a lateral explosion caused by 5 and 7 kg of TNT at the stand-off distances of 2, 5, and 10 m from the wal...

International Journal of Integrated Engineering

A high amount of energy is required to produce different types of clay and sand-lime bricks, and ... more A high amount of energy is required to produce different types of clay and sand-lime bricks, and a huge amount of carbon dioxide is released into the atmosphere. Also, brick waste from the destruction of dilapidated buildings pollutes the environment. Application of pozzolanic sources containing aluminosilicate and alkaline activators can be beneficial in production of geopolymer bricks, which do not need to be baked in a furnace and can be recycled. A laterite-based geopolymer brick mix design was introduced in this study as an environmental-friendly material. This type of brick is produced using available and cheap raw materials without the need for high furnace heat. The raw materials included laterite soil as aluminosilicate, laterite aggregate filler passed through sieve No. 8 and an alkaline activating solution with different concentrations. The effect of laterite aggregate size on the compressive strength of these brick samples was investigated. The results showed that the co...

International Journal of Integrated Engineering, 2017

One of the most important examples of transverse excitation of beam-columns is structural reinfor... more One of the most important examples of transverse excitation of beam-columns is structural reinforced concrete (RC) columns under blast loading. Under accidental or intentional explosions next to the buildings, external columns are the most critical and vulnerable structural elements. In this paper, tow analytical approaches are used to predict the first maximum dynamic response of rectangular RC column under simultaneously effect of axial force and transverse blast loading. The first analytical model is based on continuous formulation of Euler-Bernoulli beam theory and the second model is a single degree of freedom (SDOF) approach. Both of the approaches consider strain rate effects on nonlinear behavior of materials (concrete and steel reinforcement) and secondary effects of P-δ. Results of proposed models for predicting the first maximum lateral response of column under impulsive, dynamic and quasi-static loading regimes are compared to the results of nonlinear finite element anal...

E3S Web of Conferences, 2021

This paper presents two simple and robust technique for response estimating of single-degree-of-f... more This paper presents two simple and robust technique for response estimating of single-degree-of-freedom (SDOF) structural systems. The impulse method, because it is formulated based on the fundamentals of dynamics; especially, the linear impulse concept, and also the energy method, because the main idea of this method is inspired by energy conservation principles. These methods can strongly cope with linear damped systems for which damping ratio ζ is greater than 0.01. Assessment of SDOF dynamic systems under any arbitrary excitations is easily possible through the proposed methods. There is no error propagation through the solving process. The numerical example reveals the simplicity and robustness of the new technique compared to Duhamel’s integral and similar techniques. Finally, a numerical example is investigated to demonstrate the efficiency of the algorithms. The most famous record of El Centro ground motion is applied to the systems. The obtained results show that the new al...

در تحلیل و طراحی بسیاری از سازههای بتن مسلح در برابر انفجار از تحلیل تکدرجه آزادی (SDOF) استفاد... more در تحلیل و طراحی بسیاری از سازههای بتن مسلح در برابر انفجار از تحلیل تکدرجه آزادی (SDOF) استفاده میشود. عموما، در این روش تحلیل، پاسخ خمشی اعضا در نظر گرفته میشود اما در اعضایی که دارای بار محوری باشند لنگرهای ثانویه (P-δ) نیز اهمیت پیدا میکند. در زمان وقوع انفجار در داخل و یا نزدیکی ساختمانهای بتن مسلح ستونهای آن در معرض فشار جانبی ناشی از موج انفجار قرار میگیرد. در این ستونها، که گاها بارهای محوری قابل توجهی را تحمل میکنند، نادیده گرفتن لنگرهای P-δ تحت بارگذاری جانبی انفجار میتواند ریسک بالایی به همراه داشته باشد. در این مقاله به توصیف روشی ساده برای درنظرگرفتن پاسخ P-δ و همچنین اثرات نرخ کرنش (که در بارگذاریهای دینامیکی شدید بسیار اهمیت پیدا میکند) در تحلیل SDOF ستونهای بتن مسلح تحت اثر همزمان بار محوری فشاری و بار جانبی ناشی از انفجار پرداخته شده است. پاسخهای حاصل از روش SDOF با تحلیل اجزای محدود با استفاده از نرمافزار LS-DYNA مقایسه میشود. در اینجا، در طی مراحل حل معادلات حرکت سیستم SDOF لنگرهای ثانویه به روش بار جانبی معادل و اثرات نرخ کرنش به صورت ضرایب اف...

Journal of Rehabilitation in Civil Engineering, 2020

In the current study, the effect of the extreme lateral loading on the square and circular Reinfo... more In the current study, the effect of the extreme lateral loading on the square and circular Reinforced Concrete (RC) columns with and without retrofitting was investigated. 3D finite element modeling of the columns and impact loading condition was performed using the ABAQUS/Explicit software. The data of a real scale blast test carried out in our previous study were used to verify the modeling accuracy. The effect of secondary moments due to axial load, different geometrical characteristics of the steel jacket, compressive strength of the concrete, and the longitudinal reinforcement on the explosive capacity of the column and its residual axial strength were studied. Results showed that the circular columns perform better under the sudden lateral pressure than equivalent square ones. Also, steel jacketing increased the explosive capacity of the column, which was more effective in the circular columns than the square ones. The results also indicated that steel jacketing with less buck...

Shock and Vibration, 2017

Different factors can affect blast response of structural components. Hence, experimental tests c... more Different factors can affect blast response of structural components. Hence, experimental tests could be the best method for evaluating structures under blast loading. Therefore, an experimental explosion loading has been done on RC members by the authors. Four RC components, with identical geometry and material, with and without axial load were imposed to air blast. Observed data of the members’ response under blast loading was used for validation of finite element modeling process using ABAQUS software. With respect to complexity, limitations, and high costs of experimental tests, analytical studies and software modeling can be good alternatives. Accordingly, in this paper, the behavior of 6 different models of normal and strengthened RC columns under blast loading was evaluated using ABAQUS. Strengthening configurations considered here were designed for enhancing axial capacity of RC columns. Therefore, we can investigate the effectiveness of axial strengthening of column on its ...

European Journal of Sustainable Development

Columns are the most important load bearing structural elements in buildings. Under the effect of... more Columns are the most important load bearing structural elements in buildings. Under the effect of external explosions near the building, columns in the ground and first floors may have severe damage that can cause progressive collapse of the whole building frames. Residual axial load bearing capacity of the reinforced concrete column after the effect of lateral blast loading could be a practical criterion to damage assessment of the column. This is essential to determine whether the column has to be replaced or repaired for future use. In this paper, residual axial capacity of the square RC columns under the effect of initial axial force and lateral blast loading is investigated. Explicit finite element package LS-DYNA is used for analysis of the considered models and determining their residual capacity. There are some empirical formulas for estimating of the residual axial capacity of the blast damaged RC columns including Bao and Li (2010), Wu et al (2010) and Arlery et al (2013). Here, FEM results are compared to the estimations of these formulas. Different levels of initial axial force in the columns and different scale distances of blast loading are considered.

International Journal of Advancements in Technology

In this paper, moment-curvature behavior of reinforced concrete column with constant axial load i... more In this paper, moment-curvature behavior of reinforced concrete column with constant axial load is determined using finite element method and then it is introduced to a single degree of freedom (SDOF) model based on Euler-Bernoulli theory. Using this SDOF model, dynamic response of the RC column under the blast loading is estimated. The introduced SDOF includes secondary moments (P-δ) effects, nonlinear behavior of the material and effects of strain rate on concrete and steel materials through the time calculation of the model. Results obtained from SDOF model for transverse displacement of RC column under blast loading is compared to analysis by finite element software OPENSEES. Then, introduced SDOF method is used for drawing Pressure-Impulse (P-I) diagram of the column with considering the presence of axial compressive load. According to the results, introduced SDOF model has simple and quick computations and accuracy of predictions is acceptable.