Strengthening of concrete structures with buckling braces and buckling restrained braces

Mazloom, Moosa,Pourhaji, Pardis,Farash, Abbas Moosa,Sanati, Amir Hossein Techno-Press 2018 Structural monitoring and maintenance Vol.5 No.3

The purpose of this article is to strengthen concrete structures using buckling and non-buckling braces. Connection plates are modeled in three shapes including the effect of 1.5t hinge zone length, 2t one and without the zone (1.5t-CP, 2t-CP and WCP). According to the verification performed with ABAQUS software, the connection plates which are superior in ductility and strengthening are found. The results show adding steel braces in concrete moment frames increase the strength and stiffness of the structures up to about 12 and 3 times, respectively. The frame strength increased about 21 and 25 percent with considering the effect of 2t hinge length in connection plates compared to 1.5t-CPs and WCPs. Also the ductility of retrofitted frames with 2t-CP improved 2.06 times more than WCP ones. Thus, 2t-CP sample is the best choice for connecting steel braces to concrete moment frames for retrofitting them. Afterwards, optimum conditions for elemental coating in braces with no buckling are assessed. The length of concrete coatings could be reduced about 30 percent, and buckling did not occur. Therefore, the weight of restraining coating decreased, and its performance improved. It is worth noting that BRBs could be constructed with only steel materials, which have outer steel tubes too. In fact, only the square cross sections of the tube profiles are appropriate for removing the filler concrete, and the rectangular ones are prone to buckle around their weak axis.

Long-term quality control of self-compacting semi-lightweight concrete using short-term compressive strength and combinatorial artificial neural networks

Moosa Mazloom,Saeed Farahani Tajar,Farzan Mahboubi 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.25 No.5

Artificial neural networks are used as a useful tool in distinct fields of civil engineering these days. In order to control long-term quality of Self-Compacting Semi-Lightweight Concrete (SCSLC), the 90 days compressive strength is considered as a key issue in this paper. In fact, combined artificial neural networks are used to predict the compressive strength of SCSLC at 28 and 90 days. These networks are able to re-establish non-linear and complex relationships straightforwardly. In this study, two types of neural networks, including Radial Basis and Multilayer Perceptron, were used. Four groups of concrete mix designs also were made with two water to cement ratios (W/C) of 0.35 and 0.4, as well as 10% of cement weight was replaced with silica fume in half of the mixes, and different amounts of superplasticizer were used. With the help of rheology test and compressive strength results at 7 and 14 days as inputs, the neural networks were used to estimate the 28 and 90 days compressive strengths of above-mentioned mixes. It was necessary to add the 14 days compressive strength in the input layer to gain acceptable results for 90 days compressive strength. Then proper neural networks were prepared for each mix, following which four existing networks were combined, and the combinatorial neural network model properly predicted the compressive strength of different mix designs.

Compressive, shear and torsional strength of beams made of self-compacting concrete

Moosa Mazloom,Amirali Saffari,Morteza Mehrvand 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.15 No.6

The aim of this study is to provide experimental data regarding the compressive, shear and torsional strength of self-compacting concrete (SCC) used in rectangular beams, and then comparing the results with the equations presented by the CSA A23.3-04 and ACI 318-11. In fact, the gathered information in this field is quite useful for calibrating the computer models of other researchers. The other goal of this study was to investigate the effects of silica fume and superplasticizer dosages on the mechanical properties of SCC. In this research, SCC is made based on 16 different type mixing layout. Also two normal concrete (NC) or vibrating concrete are constructed to compare the results of SCC and NC. This work concentrated on concrete mixes having water/binder ratios of 0.45 and 0.35, which contained constant total binder contents of 400 kg/m3 and 500 kg/m3, respectively. The percentages of silica fume that replaced cement were 0% and 10%. The superplasticizer dosages utilized in the mixtures were 0.4%, 0.8%, 1.2% and 1.6% of the weight of cement. Beam dimensions used in this test were 30×30×120 cm3.The results of this research indicated that shear and torsional strength of SCC beams to be used in computer models can be calculated utilizing the equations presented in CSA A23.3-04 and ACI 318-11. Keywords: self-compacting concrete; rectangular beam; shear strength

Incorporation of Steel Frames in Masonry Buildings for Reduction of Earthquake-Induced Life Loss

Moosa Mazloom 대한토목학회 2013 KSCE JOURNAL OF CIVIL ENGINEERING Vol.17 No.4

This paper describes the seismic retrofit of masonry structures by introducing some steel moment resisting frames within the buildings. The intent is not to improve the seismic performance of masonry structures but to present protective steel shells within the structures that provide protection from loss of life. The main idea is that occupants can seek refuge within the steel frames as soon as the earthquake ground motions are felt. The steel frames do not carry any service loads before an earthquake. However, if a near field seismic event happens and the load bearing walls of the buildings are destroyed, some parts of their floors, which are in the retrofitted areas, will fall on the roof of the installed frames; consequently, the occupants who have sheltered in these areas will survive. This paper expresses the experimental work to assess the seismic performance of moment resisting steel frames in masonry buildings, and also it compares the test results with those obtained from linear time history and nonlinear pushover analyses. For time history analysis, the 1940 El Centro, 2003 Bam, and 1990 Manjil earthquake records scaled at the maximum peak ground acceleration assumed by the Iranian Technical Standards, equal to 0.35 g, were utilized as inputs. The results of experimental work, time history and pushover analyses show that the strength and displacement capacity of the steel frames are adequate to accommodate the distortions generated by seismic loads and aftershocks.

Evaluating the settlement of lightweight coarse aggregate in self-compacting lightweight concrete

Moosa Mazloom,Farzan Mahboubi 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.2

The purpose of this paper is to evaluate the settlement of lightweight coarse aggregate of self-compacting lightweight concrete (SCLC) after placement of concrete on its final position. To investigate this issue, sixteen samples of concrete mixes were made. The water to cementitious materials ratios of the mixes were 0.35 and 0.4. In addition to the workability tests of self-compacting concrete (SCC) such as slump flow, V-funnel and L-box tests, a laboratory experiment was made to examine the segregation of lightweight coarse aggregate in concrete. Because of the difficulties of this test, the image processing technique of MATLAB software was used to check the segregation above too. Moreover, the fuzzy logic technique of MATLAB software was utilized to improve the clarity of the borders between the coarse aggregate and the paste of the mixtures. At the end, the results of segregation tests and software analyses are given and the accuracy of the software analyses is evaluated. It is worth noting that the minimum and maximum differences between the results of laboratory tests and software analyses were 1.2% and 9.19% respectively. It means, the results of image processing technique looks exact enough for estimating the segregation of lightweight coarse aggregate in SCLC.

Direct and indirect forecasting of the money multiplier and velocity of circulation in the United Kingdom

Moosa, Imad A,Kim, Jae H. 한국국제경제학회 2004 International Economic Journal Vol.18 No.1

This paper compares the direct and indirect methods of predicting the money multiplier and velocity of circulation in the U.K. economy. Forecasts are generated using the autoregressive (AR) model and Harvey’s structural time series model. In addition to point forecasts, prediction intervals (calculated by using the recently proposed bootstrap-after-bootstrap) are used for comparing forecasting accuracy. The results turn out to be mixed but the overall evidence seems to be in favour of the direct method. It is suggested that this may be due to the pooling of time series (as implied by the definition), which reduces the noise associated with individual time series.

Experimental Investigation and Quantum Chemical Calculations of Some (Chlorophenyl Isoxazol-5-yl) Methanol Derivatives as Inhibitors for Corrosion of Mild Steel in 1 M HCl Solution

Moosa Es’haghi,Rogayeh Sadeghzadeh,Ladan Ejlali,Hadi Basharnavaz,Kambiz Seyyedi 한국부식방식학회 2019 Corrosion Science and Technology Vol.18 No.5

In this study, two novel Schiff base compounds including (3-(4-Chlorophenyl isoxazole-5-yl) methanol and(3-(2,4 dichlorophenol isoxazole-5-yl) methanol as corrosion inhibitors for mild steel in 1 M hydrochloricacid solution were investigated by potentiodynamic polarization, electrochemical impedance spectroscopy(EIS), and density functional theory (DFT) computations. The results showed that the corrosion inhibitionefficiency (IE) is remarkably enhanced with the growing concentration of the Schiff base inhibitors. Theresults from Tafel polarization and EIS methods showed that IE decreases with gradual increments of temperature. This process can be attributed to the displacement of the adsorption/desorption balance and hence to thediminution of the level of a surface coating. Also, the adsorption of two inhibitors over mild steel followedthe Langmuir adsorption isotherm. Too, the results of the scanning electron microscope (SEM) images showedthat the Schiff base inhibitors form an excellent protective film over mild steel and verified the resultsby electrochemical techniques. Additionally, the results from the experimental and those from DFT computationsare in excellent accordance.

Predicting the indirect tensile strength of self-compacting concrete using artificial neural networks

Moosa Mazloom,M.M. Yoosefi 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.12 No.3

This paper concentrates on the results of experimental work on tensile strength of self-compacting concrete (SCC) caused by flexure, which is called rupture modulus. The work focused on concrete mixes having water/binder ratios of 0.35 and 0.45, which contained constant total binder contents of 500 kg/m3 and 400 kg/m3, respectively. The concrete mixes had four different dosages of a superplasticizer based on polycarboxylic with and without silica fume. The percentage of silica fume that replaced cement in this research was 10%. Based upon the experimental results, the existing equations for anticipating the rupture modulus of SCC according to its compressive strength were not exact enough. Therefore, it is decided to use artificial neural networks (ANN) for anticipating the rupture modulus of SCC from its compressive strength and workability. The conclusion was that the multi layer perceptron (MLP) networks could predict the tensile strength in all conditions, but radial basis (RB) networks were not exact enough in some circumstances. On the other hand, RB networks were more users friendly and they converged to the final networks quicker.

Comparison of Cervical Cell Morphology Using Two Different Cytology Techniques for Early Detection of Pre-Cancerous Lesions

Moosa, Najla Yussuf,Khattak, Nuzhat,Alam, Muhammad Irfan,Sher, Alam,Shah, Walayat,Mobashar, Shumaila,Alam, Muhammad Imran,Javid, Asima Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.2

Cervical cancer is an issue of foremost importance globally, specifically affecting the developing nations. Significant advances have taken place with regard to diagnosis of cervical cancer, especially with screening. Appropriate screening measures can thus reduce the incidence of cervical cancer. The most desirable screening technique should be less invasive, easy to perform, cost-effective and cover a wide range of diagnostic icons. Manual liquid based cytology (MLBC) can be considered as one of the suitable technique for screening with the above-mentioned benefits. The aim of the current study was to compare two cervical screening techniques on the basis of different morphological parameters and staining parameters by using modified acetic acid Pap staining to see the possibility of reducing time economy involved in conventional Pap staining (CPS). The study was conducted on a total 88 cases and all were analyzed with both MLBC and CPS. Forty eight cases that were regarded as satisfactory on the basis of Bethesda system by both methods were further recruited for investigation. Their morphological parameters and staining quality were compared and scored according to a scoring system defined in the study. Quality indices was calculated for both staining procedures and smear techniques.

ARE ASIAN MARKETS INTEGRATED ? EVIDENCE FOR SIX COUNTRIES VIS - A - VIS JAPAN

MOOSA, IMAD A.,BHATTI, RAZZAQUE H. 한국국제경제학회 1997 International Economic Journal Vol.11 No.1