Theoretical and experimental serviceability performance of SCCs connections

Maghsoudi, Ali Akbar Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.2

The Self Compacting Concrete, SCC is the new generation type of concrete which is not needed to be compacted by vibrator and it will be compacted by its own weight. Since SCC is a new innovation and also the high strength self compacting concrete, HSSCC behavior is like a brittle material, therefore, understanding the strength effect on the serviceability performance of reinforced self compacting concretes is critical. For this aim, first the normal and high strength self compacting concrete, NSSCC and HSSCC was designed. Then, the serviceability performance of reinforced connections consisting of NSSCC and HSSCC were investigated. Twelve reinforced concrete connections (L = 3 m, b = 0.15 m, h = 0.3 m) were simulated, by this concretes, the maximum and minimum reinforcement ratios ${\rho}$ and ${\rho}^{\prime}$ (percentage of tensile and compressive steel reinforcement) are in accordance with the provision of the ACI-05 for conventional RC structures. This study was limited to the case of bending without axial load, utilizing simple connections loaded at mid span through a stub (b = 0.15 m, h = 0.3 m, L = 0.3 m) to simulate a beam-column connection. During the test, concrete and steel strains, deflections and crack widths were measured at different locations along each member. Based on the experimental readings and observations, the cracked moment of inertia ($I_{cr}$) of members was determined and the results were compared with some selective theoretical methods. Also, the flexural crack widths of the members were measured and the applicability for conventional vibrated concrete, as for ACI, BS and CSA code, was verified for SCCs members tested. A comparison between two Codes (ACI and CSA) for the theoretical values cracking moment is indicate that, irrespective of the concrete strength, for the specimens reported, the prediction values of two codes are almost equale. The experimental cracked moment of inertia $(I_{cr})_{\exp}$ is lower than its theoretical $(I_{cr})_{th}$ values, and therefore theoretically it is overestimated. Also, a general conclusion is that, by increasing the percentage of ${\rho}$, the value of $I_{cr}$ is increased.

Flexural ductility of HSC members

Maghsoudi, A.A.,Bengar, H. Akbarzadeh Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.24 No.2

In seismic areas, ductility is an important factor in design of high strength concrete (HSC) members under flexure. A number of twelve HSC beams with different percentage of ${\rho}$ & ${\rho}^{\prime}$ were cast and incrementally loaded under bending. The effect of ${\rho}^{\prime}$ on ductility of members were investigated both qualitatively and quantitatively. During the test, the strain on the concrete middle faces, on the tension and compression bars, and also the deflection at different points of the span length were measured up to failure. Based on the obtained results, the serviceability and ultimate behavior, and especially the ductility of the HSC members are more deeply reviewed. Also a comparison between theoretical and experimental results are reported here.

Multidisciplinary optimization of a stiffened shell by genetic algorithm

Mahdi Maghsoudi Mehrabani,Ali Asghar Jafari,Mohammad Azadi 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.2

Vibration analysis of simply supported rotating cross-ply laminated stiffened cylindrical shell is performed using an energy approach which includes variational and averaging method. The stiffeners include rings and stringers. The equations are obtained by Rayleigh-Ritz method and Sander’s relations. To validate the present method, the results are compared to the results available in other literatures. A good adoption is observed in different type of results including isotropic shells, rotating laminated shells, stiffened isotropic shells and stiffened laminated shells. Then, the optimization of parameters due to shell and stiffeners is conducted by genetic algorithm (GA) method under weight and frequency constraints. Stiffener shape, material properties and dimensions are also optimized.

Integration of GIS and analytical hierarchy process method for locating road emergency medical services station

Soroush Maghsoudy,Ali Mansour Khaki,Barat Mojaradi,Behrooz Ghobadipour,Fereydoun Naghibi 한국자원공학회 2015 Geosystem engineering Vol.18 No.2

This article describes the application of a well-known multi-criteria decision-making technique called analytical hierarchy process (AHP) to locate emergency medical service (EMS) along US interstate highway I-65 from Montgomery to Birmingham, Alabama. Five weighting methods were applied, including Row Sum, Column Sum, Arithmetic Average, Geo-Mean, and Eigen Vector to determine weights of criteria. A number of experts were asked to evaluate the importance of selected criteria according to a nine-point scale (the Saaty rating scale). Afterwards, a weighted overlay method was applied to evaluate pixel adequacy and to identify areas with highest potential to establish the EMS along the road. After that all alternatives were ranked with the AHP method, and finally, sensitivity analysis of criteria weights was performed. The proposed method shows that locating EMS stations is very sensitive to Distance to City, Distance to Intersection, and Distance to Police Station criteria weights, and it should be considered in selecting experts and criteria weighting process.

A New Methanol-feeding Strategy for the Improved Production of β-galactosidase in High Cell-density Fed-batch Cultures of Pichia pastoris Mut+ Strains

Amir Maghsoudi,Safoura Hosseini,Seyed Abbas Shojaosadati,Ebrahim Vasheghani-Farahani,Mohsen Nosrati,Ali Bahrami 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.1

Developing novel methanol-feeding strategies for the improved production of heterologous proteins in high cell-density fed-batch cultures of Pichia pastoris has been of great interest during recent years. In this study, a recombinant P. pastoris strain (GS115/His+ Mut+) producing β-galactosidase (β-Gal) was used to investigate conventional feeding strategies and to develop a new strategy to increase the recombinant protein production during fedbatch cultures on methanol. Three types of conventional methanol-feeding strategies, including μ-stat, dissolved oxygen-stat (DO-stat) and constant methanol concentration were investigated and compared with respect to alcohol oxidase (AOX), formate dehydrogenase (FDH) and β-gal activities, and cell dry weight (CDW), methanol, and formaldehyde concentration variations during the production phase. Methanol feeding with μ-stat 0.025/h exhibited the highest β-gal activity. Supplementing ammonium and magnesium in μ-stat 0.025/h did not affect the cell growth or methanol or formaldehyde concentrations throughout the fermentation but did improved the maximum β-gal activity from 148.2 to 158.1 kU/mL. A new three-step methanol-feeding strategy was developed based on the results obtained from conventional feeding strategies, which started with μ-stat 0.025/ h for 5 h, then μ-stat 0.030/h, and finally, was switched to DO-stat when maintaining the DO above 20% air saturation became difficult. Implementation of this new feeding strategy resulted in a CDW of 107.2 ±0.7 g/L, AOX specific activity of 0.1890 ± 0.0030 U/mg CDW, and β-gal activity of 173.5 ± 2.1 kU/mL after 29 h of fermentation, which shows a 5.6, 29.1, and 15.7%increase in CDW, AOX, and β-gal activity, respectively,compared to that of μ-stat at 0.025/h.

Theoretical and experimental serviceability performance of SCCs connections

Ali Akbar Maghsoudi 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.2

The Self Compacting Concrete, SCC is the new generation type of concrete which is not needed to be compacted by vibrator and it will be compacted by its own weight. Since SCC is a new innovation and also the high strength self compacting concrete, HSSCC behavior is like a brittle material, therefore, understanding the strength effect on the serviceability performance of reinforced self compacting concretes is critical. For this aim, first the normal and high strength self compacting concrete, NSSCC and HSSCC was designed. Then, the serviceability performance of reinforced connections consisting of NSSCC and HSSCC were investigated. Twelve reinforced concrete connections (L = 3 m, b = 0.15 m, h = 0.3 m) were simulated, by this concretes, the maximum and minimum reinforcement ratios ρ and ρ' (percentage of tensile and compressive steel reinforcement) are in accordance with the provision of the ACI-05 for conventional RC structures. This study was limited to the case of bending without axial load, utilizing simple connections loaded at mid span through a stub (b = 0.15 m, h = 0.3 m, L = 0.3 m) to simulate a beam-column connection. During the test, concrete and steel strains, deflections and crack widths were measured at different locations along each member. Based on the experimental readings and observations, the cracked moment of inertia (I_cr) of members was determined and the results were compared with some selective theoretical methods. Also, the flexural crack widths of the members were measured and the applicability for conventional vibrated concrete, as for ACI, BS and CSA code, was verified for SCCs members tested. A comparison between two Codes (ACI and CSA) for the theoretical values cracking moment is indicate that, irrespective of the concrete strength, for the specimens reported,the prediction values of two codes are almost equale. The experimental cracked moment of inertia (I_cr)_exp is lower than its theoretical (I_cr)_th values, and therefore theoretically it is overestimated. Also, a general conclusion is that, by increasing the percentage of ρ, the value of I_cr is increased.

Properties Assessment of Concrete Containing Sirjan Pozzolan

Ali Akbar Maghsoudi,Hamed Ahmadi Moghadam 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.5

The possibility of using Sirjan (a city located in the west of Kerman province of Iran) Pozzolan (SP) in concrete was studied in this study. To find out the proper percentage of the cement replacement by pozzolan, a number of concrete specimens containing of 5 to 16% of pozzolan with constant water to binder ratio of 0.5 were casted and the compressive strength, flexural strength, shrinkage and expansion for different curing conditions were measured up to 365 days. The tests results show that the cement replacement by Sirjan Pozzolan (SP) caused both the quality and mechanical property alterations. Also it can be seen that the flexural strength, shrinkage and expansion of specimens increased, whereas the compressive strength decreased in initial days. Also To verify the pozzolanic mechanism, the specimens were examined by SEM.

The analytical solution for buckling of curved sandwich beams with a transversely flexible core subjected to uniform load

Poortabib, A.,Maghsoudi, M. Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.2

In this paper, linear buckling analysis of a curved sandwich beam with a flexible core is investigated. Derivation of equations for face sheets is accomplished via the classical theory of curved beam, whereas for the flexible core, the elasticity equations in polar coordinates are implemented. Employing the von-Karman type geometrical non-linearity in strain-displacement relations, nonlinear governing equations are resulted. Linear pre-buckling analysis is performed neglecting the rotation effects in pre-buckling state. Stability equations are concluded based on the adjacent equilibrium criterion. Considering the movable simply supported type of boundary conditions, suitable trigonometric solutions are adopted which satisfy the assumed edge conditions. The critical uniform load of the beam is obtained as a closed-form expression. Numerical results cover the effects of various parameters on the critical buckling load of the curved beam. It is shown that, face thickness, core thickness, core module, fiber angle of faces, stacking sequence of faces and openin angle of the beam all affect greatly on the buckling pressure of the beam and its buckled shape.

Flexural strengthening of continuous unbonded post-tensioned concrete beams with end-anchored CFRP laminates

Ghasemi, Saeed,Maghsoudi, Ali A.,Bengar, Habib A.,Ronagh, Hamid R. Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.53 No.6

This paper provides the results of an experimental investigation into the flexural behavior of continuous two-span unbonded post-tensioned high strength concrete (HSC) beams, strengthened by end-anchored CFRP laminates of different configurations in the hogging region. Implementing two different configurations of end-anchorage systems consisting of steel plates and bolts and carefully monitoring the development of strains throughout the load history using sufficiently large number of strain gauges, the response of beams including the observed crack propagations, beam deflection, modes of failure, capacity enhancement at service and ultimate and the amount of moment redistribution are measured, presented and discussed. The study is appropriate in the sense that it covers the more commonly occurring two span beams instead of the simply supported beams investigated by others. The experiments reconfirmed the finding of others that proper installation of composite strengthening system is most important in the quality of the bond which is essential for the internal transfer of forces. It was also found that for the tested two span continuous beams, the capacity enhancement is more pronounced at the serviceability level than the ultimate. This is an important finding as the design of these beams is mostly governed by the serviceability limit state signifying the appropriateness of the suggested strengthening method. The paper provides quantitative data on the amount of this capacity enhancement.

Flexural ductility of reinforced HSC beams strengthened with CFRP sheets

Hashemi, Seyed Hamid,Maghsoudi, Ali Akbar,Rahgozar, Reza Techno-Press 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.30 No.4

Externally bonding fiber reinforced polymer (FRP) sheets with an epoxy resin is an effective technique for strengthening and repairing reinforced concrete (RC) beams under flexural loads. Their resistance to electro-chemical corrosion, high strength-to-weight ratio, larger creep strain, fatigue resistance, and nonmagnetic and nonmetallic properties make carbon fiber reinforced polymer (CFRP) composites a viable alternative to bonding of steel plates in repair and rehabilitation of RC structures. The objective of this investigation is to study the effectiveness of CFRP sheets on ductility and flexural strength of reinforced high strength concrete (HSC) beams. This objective is achieved by conducting the following tasks: (1) flexural four-point testing of reinforced HSC beams strengthened with different amounts of cross-ply of CFRP sheets with different amount of tensile reinforcement up to failure; (2) calculating the effect of different layouts of CFRP sheets on the flexural strength; (3) Evaluating the failure modes; (4) developing an analytical procedure based on compatibility of deformations and equilibrium of forces to calculate the flexural strength of reinforced HSC beams strengthened with CFRP composites; and (5) comparing the analytical calculations with experimental results.