Side-NSM composite technique for flexural strengthening of RC beams

Akter Hosen,Mohd Zamin Jumaat,A. B. M. Saiful Islam,Abdus Salam,Kim Hung Mo 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.4

Reinforced concrete (RC) infrastructures often require strengthening due to error in design, degradation of materials properties after prolong utilization and increases load carrying capacity persuaded by new use of the structures. For this purpose, a newly proposed Side Near Surface Mounted (SNSM) composite technique was used for flexural strengthening of RC beam specimens. Analytical and non-linear finite element modeling (FEM) using ABAQUS were performed to predict the flexural performance of RC specimens strengthened with S-NSM using steel bars as a strengthening reinforcement. RC beams with various SNSM reinforcement ratios were tested for flexural performance using four-point bending under monotonic loading condition. Results showed significantly increase the yield and ultimate strengths up to 140% and 144% respectively and improved failure modes. The flexural response, such as failure load, mode of failure, yield load, ultimate load, deflection, strain, cracks characteristic and ductility of the beams were compared with those predicted results. The strengthened RC beam specimens showed good agreement of predicted flexural behavior with the experimental outcomes.

Comparison of shear lag in structural steel building with framed tube and braced tube

Mazinani, Iman,Jumaat, Mohd Zamin,Ismail, Z.,Chao, Ong Zhi Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.3

Under lateral loads Framed Tube (FT) system exhibits reduction of cantilever efficiency due to the effect of shear lag. Braced Tube (BT) represents a valuable solution to overcome shear lag problems by stiffening the exterior frame with diagonal braced members. This study investigates the effect of shear lag on BT and FT under wind load. Shear lag and top-level displacement results are compared with previous findings by researchers on FT and BT systems. The investigation of the effect of various configurations in BT on the reduction the shear lag is another objective of this study. The efficiency of each structure is evaluated using the linear response spectrum analysis to obtain shear lag. STADD Pro software is used to run the dynamic analysis of the models. Results show there is relatively less shear lag in all the BT configurations compared to the FT structural system. Moreover, the comparison of the obtained result with those derived by previous studies shows that shear lag is not proportional to lateral displacement. With respect to results, optimum BT configuration in term of lower shear lag caused by lateral loads is presented.

Comparison of shear lag in structural steel building with framed tube and braced tube

Iman Mazinani,Mohd Zamin Jumaat,Z. Ismail,Ong Zhi Chao 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.3

Under lateral loads Framed Tube (FT) system exhibits reduction of cantilever efficiency due to the effect of shear lag. Braced Tube (BT) represents a valuable solution to overcome shear lag problems by stiffening the exterior frame with diagonal braced members. This study investigates the effect of shear lag on BT and FT under wind load. Shear lag and top-level displacement results are compared with previous findings by researchers on FT and BT systems. The investigation of the effect of various configurations in BT on the reduction the shear lag is another objective of this study. The efficiency of each structure is evaluated using the linear response spectrum analysis to obtain shear lag. STADD Pro software is used to run the dynamic analysis of the models. Results show there is relatively less shear lag in all the BT configurations compared to the FT structural system. Moreover, the comparison of the obtained result with those derived by previous studies shows that shear lag is not proportional to lateral displacement. With respect to results, optimum BT configuration in term of lower shear lag caused by lateral loads is presented.

Potential side-NSM strengthening approach to enhance the flexural performance of RC beams: Experimental, numerical and analytical investigations

Md. Akter Hosen,Mohd Zamin Jumaat,A.B.M. Saiful Islam,Khalid Ahmed Al Kaaf,Mahaad Issa Shammas,Ibrahim Y. Hakeem,Mohammad Momeen Ul Islam 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.85 No.2

The performance of reinforced concrete (RC) beam specimens strengthened using a newly proposed Side Near Surface Mounted (S-NSM) technology was investigated experimentally in this work. In addition, analytical and nonlinear finite element (FE) modeling was exploited to forecast the performance of RC members reinforced with S-NSM utilizing steel bars. Five (one control and four strengthened) RC beams were evaluated for flexural performance under static loading conditions employing four-point bending loads. Experimental variables comprise different S-NSM reinforcement ratios. The constitutive models were applied for simulating the non-linear material characteristics of used concrete, major, and strengthening reinforcements. The failure load and mode, yield and ultimate strengths, deflection, strain, cracking behavior as well as ductility of the beams were evaluated and discussed. To cope with the flexural behavior of the tested beams, a 3D non-linear FE model was simulated. In parametric investigations, the influence of S-NSM reinforcement, the efficacy of the S-NSM procedure, and the structural response ductility are examined. The experimental, numerical, and analytical outcomes show good agreement. The results revealed a significant increase in yield and ultimate strengths as well as improved failure modes.

Palm oil industry’s bi-products as coarse aggregate in structural lightweight concrete

Md. Nazmul Huda,Mohd Zamin Jumaat,A. B. M. Saiful Islam,Kh Mahfuz ud Darain,M. Obaydullah,Md. Akter Hosen 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.5

Recent trend is to use the lightweight concrete in the construction industry because it has several advantages over normal weight concrete. The Lightweight concrete can be produced from the industrial waste materials. In South East Asian region, researchers are very keen to use the waste materials such as oil palm shell (OPS) and palm oil clinker (POC) from the palm oil producing industries. Extensive research has been done on lightweight concrete using OPS or POC over the last three decades. In this paper the aggregate properties of OPS and POC are plotted in conjunction with mechanical and structural behavior of OPS concrete (OPSC) and POC concrete (POCC). Recent investigation on the use of crushed OPS shows that OPSC can be produced to medium and high strength concrete. The density of OPSC and POCC is around 20-25% lower than normal weight concrete. Generally, mechanical properties of OPSC and POCC are comparable with other types of lightweight aggregate concrete. It can be concluded from the previous study that OPSC and POCC have the noteworthy potential as a structural lightweight concrete.

Eliminating concrete cover separation of NSM strengthened beams by CFRP end anchorage

Md. Akter Hosen,Mohd Zamin Jumaat,A. B. M. Saiful Islam,Mohamed Kamruzzaman,Md. Nazmul Huda,Mahmudur Rahman Soeb 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.56 No.6

Upgrading or strengthening of existing reinforced concrete (RC) infrastructure is an emerging demand nowadays. Near Surface Mounted (NSM) technique is very promising approach for flexural strengthening of RC members. However, premature failure such as concrete cover separation failure have been a main concern in utilizing this technique. In this study, U-wrap end anchorage with carbon fiber reinforced polymer (CFRP) fabrics is proposed to eliminate the concrete cover separation failure. Experimental programs were conducted to the consequence of U-wrap end anchorage on the flexurally strengthened RC beams with NSM- steel. A total of eight RC rectangular beam specimens were tested. One specimen was kept unstrengthened as a reference; three specimens were strengthened with NSM-steel bars and the remaining four specimens were strengthened with NSM-steel bars and U-wrap end anchorage using CFRP fabrics. A 3D non-linear finite element model (FEM) was developed to simulate the flexural response of the tested specimens. It is revealed that NSM-steel (with and without end-anchors) significantly improved the flexural strength; moreover decreased deflection and strains compared with reference specimen. Furthermore, NSM-steel with end anchorage strengthened specimens revealed the greater flexural strength and improve failure modes (premature to flexure) compared with the NSM-steel without end anchorage specimens. The results also ensured that the U-wrap end anchorage completely eliminate the concrete cover separation failure.

Weight minimum design of concrete beam strengthened with glass fiber reinforced polymer bar using genetic algorithm

Md. Moshiur Rahman,Mohd Zamin Jumaat,A. B. M. Saiful Islam 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.2

This paper presents a generalized formulation for optimizing the design of concrete beam reinforced with glass fiber reinforced polymer bar. The optimization method is formulated to find the design variables leading to the minimum weight of concrete beam with constraints imposed based on ACI code provisions. A simple genetic algorithm is utilized to solve the optimization task. The weights of concrete and glass fiber reinforced polymer bar are included in the formulation of the objective function. The ultimate limit states and the serviceability limit states are included in formulation of constraints. The results of illustrated example demonstrate the efficiency of the proposed method to reduce the weight of beam as well as to satisfy the above requirement. The application of the optimization based on the most economical design concept have led to significant savings in the amount of the component materials to be used in comparison to classical design solutions.

Effect of High-cyclic Loads on Dynamic Response of Reinforced Concrete Slabs

Adiza Jamadin,Zainah Ibrahim,Mohd Zamin Jumaat,Ezahtul Shahreen Ab Wahab 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.3

Bridge reinforced concrete deck slabs are often subjected to various cyclic loadings—making regular checks for fatigue damage necessary. Several experiments on reinforced concrete structures were conducted to evaluate its mechanical fatigue behaviour. Nevertheless, adequate experimental investigations on its dynamic properties are still needed. This paper reports on the test performed on three identical reinforced concrete slabs, with different cyclic load number and after the cycles, the load was increased up to the static failure. Modal testing was performed after each step of loading to assess their dynamic performance using modal parameters (natural frequencies, mode shapes and damping ratios). Finite element model was used to predict the natural frequency of the reinforced concrete slabs and their reliability was checked through model updating. The results showed the intensity of fatigued structures causes significant changes to the modal parameters and structural loading capacity. The study explores how fatigued structure can be assessed from dynamic performance, and also can be quantified through its structural stiffness, ultimately offering a better way of using non-destructive modal testing in identifying its structural health as compared to conventional testing techniques.

Drying Shrinkage Strain of Palm-oil By-products Lightweight Concrete: A Comparison between Experimental and Prediction Models

Muhammad Aslam,Payam Shafigh,Mohd Zamin Jumaat 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.12

Drying shrinkage in concrete can be attributed to loss of moisture, variations in temperature, and the chemical reactions of cement with water and carbon dioxide, is one of the most important parameters which affects the durability and service life of the concrete structures. Recently, the lightweight concrete has got a considerable attention to be used in structural applications. Although, this concrete has very high drying shrinkage compared to conventional concrete. Therefore, the design engineers need an accurate and precise estimation of the concrete shrinkage, so that the safe and durable structure can be produced. The main objective of this research is to compare the development of drying shrinkage strain of three concrete mixes made of by-product aggregate namely oil pam shell and oil-palm-boiler clinker from the palm oil industry with the prediction models. For that purpose, ten (ACI209R, EN1992, MC2010, CEB/ FIP1990, AASHTO-LRFD, GL2000, AS3600, JSCE, SAK and B3) prediction models of drying shrinkage have been selected from the standards, codes and researchers. All suggested parameters for the prediction models were considered in the estimation of shrinkage strain for the by-product concretes. In addition, the error percentage and coefficient of variation methods have been used to compute the accuracy of prediction models. The results showed that in early ages, almost all the prediction models estimated similar results with the experimental curves. However, at later ages, only few models for each concrete predicted similar results to the experimental values.

Effect of Moorings Drag and Inertia on Response of Spar Platform

Mohammed Jameel,Abdulrahman Eyada Ibrahim,SuhailAhmad,Mohd Zamin Jumaat 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.7

Spar platform is a type of floating structure utilized for oil and gas exploration and production in deep and ultra-deep waters. Coupled analysis in present study considers Spar mooring lines as an integrated system. It incorporates the contribution of drag and inertia forces of mooring lines. A rigid classical Spar cylinder connected by four tensioned catenary mooring lines has been modeled and analysed using finite element approach. Mooring system has been modeled as hybrid beam elements. The Studies cover surge, heave, pitch and mooring line tension responses, highlighting the coupling effect. The non-linearities present in the coupled system leads to irregular behavior under regular sea states. The coupled model noticeably confirms its importance in terms of hydrodynamic damping on mooring system. There is a key variance in behavior found with and without drag and inertia forces on mooring system.