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.

Flexible Foundation Effect on Seismic Analysis of Roller Compacted Concrete (RCC) Dams Using Finite Element Method

Khaled Ghaedi,Farzad Hejazi,Zainah Ibrahim,Parveen Khanzaei 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.4

Recently, Roller Compacted Concrete (RCC) dams have become one of the most applicable types of dams across the globe. However,the basic challenge in analysis of RCC dams is evaluation of the actual response under earthquake excitations with considering flexiblefoundation and impounded water. For this purpose, a finite element model of RCC Dam-Reservoir-Foundation is accurately developedand dynamic time history analysis is utilized to assess the seismic responses in terms of acceleration, displacements, stresses, crackingpatterns and crack propagation by implementation of concrete damaged plasticity model. A verification model is carried out to show thework accuracy. Based on these explanations, the obtained results showed that, however, the hydrodynamic pressure due to the reservoirwater had great influence on seismic responses of the RCC dam with rigid foundation especially in terms of displacement response butoverall responses of the dam are greatly fluctuated while flexible foundation is taken into consideration

Computational and experimental analysis of beam to column joints reinforced with CFRP plates

Zhenyan Luo,Hamid Sinaei,Zainah Ibrahim,Mahdi Shariati,Zamin Jumaat,Karzan Wakil,Binh Thai Pham,Edy Tonnizam Mohamad,Majid Khorami 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.30 No.3

In this paper, numerical and experimental assessments have been conducted in order to investigate the capability of using CFRP for the seismic capacity improvement and relocation of plastic hinge in reinforced concrete connections. Two scaled down exterior reinforced concrete beam to column connections have been used. These two connections from a strengthened moment frame have been tested under uniformly distributed load before and after optimization. The results of experimental tests have been used to verify the accuracy of numerical modeling using computational ABAQUS software. Application of FRP plate on the web of the beam in connections to improve its capacity is of interest in this paper. Several parametric studies were carried out for CFRP reinforced samples, with different lengths and thicknesses in order to relocate the plastic hinge away from the face of the column.

Influence of fly ash and GGBFS on the pH value of cement mortar in different curing conditions

Shafigh, Payam,Yousuf, Sumra,Ibrahim, Zainah,Alsubari, Belal,Asadi, Iman Techno-Press 2021 Advances in concrete construction Vol.11 No.5

The pH of cement-based materials (CBMs) is an important factor for their durability, sustainability, and long service life. Currently, the use of supplementary cementitious materials (SCMs) is becoming mandatory due to economic, environmental, and sustainable issues. There is a decreasing trend in pH of CBMs due to incorporation of SCMs. The determination of numerical values of pH is very important for various low and high volume SCMs blended cement mortars for the better understanding of different defects and durability issues during their service life. In addition, the effect of cement hydration and pozzolanic reaction of SCMs on the pH should be determined at initial and later ages. In this study, the effect of low and high-volume fly ash (FA) and ground granulated ballast furnace slag (GGBFS) cement mortars in different curing conditions on their pH values has been determined. Thermal gravimetric analysis (TGA) was carried out to support the findings from pH measurements. In addition, thermal conductivity (k-value) and strength activity indices of these cement mortars were discussed. The results showed that pH values of all blended cement mortars were less than ordinary Portland cement (OPC) mortar in all curing conditions used. There was a decreasing tendency in pH of all mortars with passage of time. In addition, the pH of cement mortars was not only dependent on the quantity of Ca(OH)₂. The effect of adding SCMs on the pH value of cement mortar should be monitored and measured for both short and long terms.

Seismic Analysis of Roller Compacted Concrete (RCC) Dams Considering Effect of Sizes and Shapes of Galleries

Khaled Ghaedi,Mohammed Jameel,Zainah Ibrahim,P. Khanzaei 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.1

This paper compares the analysis of a Roller Compacted Concrete (RCC) dam with and without galleries under seismic loading. The effects of different sizes and shapes (circle, octagon and square) of gallery have also seen in the analysis. For this purpose, twodimensional (2D) Finite Element Model (FEM) is used for nonlinear dynamic analysis by means of finite element software, ABAQUS. In addition, Concrete Damaged Plasticity (CDP) model is also implemented to inspect the tensile damage of the dam during earthquake excitation. Kinta RCC dam of Malaysia is considered as a case study in analysis. From the seismic analysis, it was found that by increasing the size of openings, stress is developed around the galleries. As a result, the gallery with circle shape is more appropriate for the dam in comparison to gallery with square and octagon shapes. From crack propagation analysis and displacement response, it was also found that the gallery with circle shape behaves better than the gallery with square and octagon shaped.

Assessment of Rheological and Piezoresistive Properties of Graphene based Cement Composites

Sardar Kashif Ur Rehman,Zainah Ibrahim,Mohammad Jameel,Shazim Ali Memon,Muhammad Faisal Javed,Muhammad Aslam,Kashif Mehmood,Sohaib Nazar 한국콘크리트학회 2018 International Journal of Concrete Structures and M Vol.12 No.6

The concrete production processes including materials mixing, pumping, transportation, injection, pouring, moulding and compaction, are dependent on the rheological properties. Hence, in this research, the rheological properties of fresh cement paste with different content of graphene (0.03, 0.05 and 0.10% by weight of cement) were investigated. The parameters considered were test geometries (concentric cylinders and parallel plates), shear rate range (300–0.6, 200–0.6 and 100–0.6 s<SUP>−1</SUP>), resting time (0, 30 and 60 min) and superplasticizer dosage (0 and 0.1% by weight of cement). Four rheological prediction models such as Modified Bingham, Herschel–Bulkley, Bingham model and Casson model were chosen for the estimation of the yield stress, plastic viscosity and trend of the flow curves. The effectiveness of these rheological models in predicting the flow properties of cement paste was verified by considering the standard error method. Test results showed that the yield stress and the plastic viscosity increased with the increase in graphene content and resting time while the yield stress and the plastic viscosity decreased with the increase in the dosage of superplasticizer. At higher shear rate range, the yield stress increased while the plastic viscosities decreased. The Herschel–Bulkley model with the lowest average standard error and standard deviation value was found to best fit the experimental data, whereas, Casson model was found to be the most unfitted model. Graphene reduces the flow diameter and electrical resistivity up to 9.3 and 67.8% and enhances load carrying capacity and strain up to 16.7 and 70.1% of the composite specimen as compared with plain cement specimen. Moreover, it opened a new dimension for graphene-cement composite as smart sensing building construction material.

Engineering properties of coconut shell lightweight concrete: A comparative study

Pordesari, Alireza Javadi,Shafigh, Payam,Ibrahim, Zainah,Aslam, Muhammad Techno-Press 2021 Advances in concrete construction Vol.12 No.4

A vast amount of natural resources are required to produce concretes due to industrialisation and urbanisation, indicating that large quantities of raw materials are being utilised worldwide. The use of industrial wastes as an aggregate in concrete is highly recommended to promote sustainable development by reducing the consumption of natural resources. Agricultural wastes are available in large amounts, thereby making them an acceptable and reliable solution for aggregate in concrete. In this study, natural aggregates, such as coconut shell and oil palm shell, were replaced with normal coarse aggregate. The properties of concrete, such as workability, density, compressive strength in different curing regimes, splitting tensile strength, Young's modulus, drying shrinkage and water absorption were studied. The slump value and density were reduced by replacing the normal coarse aggregate with agrowaste materials. However, the compressive and splitting tensile strengths of the concrete decreased and the water absorption increased. The performance of coconut shell concrete was compared with other lightweight aggregate concrete. Results show that this concrete has better performance than oil palm shell lightweight concrete.

A review on pavement porous concrete using recycled waste materials

Ali Toghroli,Mahdi Shariati,Fathollah Sajedi,Zainah Ibrahim,Suhana Koting,Edy Tonnizam Mohamad,Majid Khorami 국제구조공학회 2018 Smart Structures and Systems, An International Jou Vol.22 No.4

Pavements porous concrete is a noble structure design in the urban management development generally enabling water to be permeated within its structure. It has also capable in the same time to cater dynamic loading. During the technology development, the quality and quantity of waste materials have led to a waste disposal crisis. Using recycled materials (secondary) instead of virgin ones (primary) have reduced landfill pressure and extraction demanding. This study has reviewed the waste materials (Recycled crushed glass (RCG), Steel slag, Steel fiber, Tires, Plastics, Recycled asphalt) used in the pavement porous concretes and report their respective mechanical, durability and permeability functions. Waste material usage in the partial cement replacement will cause the concrete production cost to be reduced; also, the concretes’ mechanical features have slightly affected to eliminate the disposal waste materials defects and to use cement in Portland cement (PC) production. While the cement has been replaced by different industrial wastes, the compressive strength, flexural strength, split tensile strength and different PC permeability mixes have depended on the waste materials’ type applied in PC production.

A review on pavement porous concrete using recycled waste materials

Toghroli, Ali,Shariati, Mahdi,Sajedi, Fathollah,Ibrahim, Zainah,Koting, Suhana,Mohamad, Edy Tonnizam,Khorami, Majid 국제구조공학회 2018 Smart Structures and Systems, An International Jou Vol.22 No.4

Pavements porous concrete is a noble structure design in the urban management development generally enabling water to be permeated within its structure. It has also capable in the same time to cater dynamic loading. During the technology development, the quality and quantity of waste materials have led to a waste disposal crisis. Using recycled materials (secondary) instead of virgin ones (primary) have reduced landfill pressure and extraction demanding. This study has reviewed the waste materials (Recycled crushed glass (RCG), Steel slag, Steel fiber, Tires, Plastics, Recycled asphalt) used in the pavement porous concretes and report their respective mechanical, durability and permeability functions. Waste material usage in the partial cement replacement will cause the concrete production cost to be reduced; also, the concretes' mechanical features have slightly affected to eliminate the disposal waste materials defects and to use cement in Portland cement (PC) production. While the cement has been replaced by different industrial wastes, the compressive strength, flexural strength, split tensile strength and different PC permeability mixes have depended on the waste materials' type applied in PC production.

Effect of curing on alkalinity and strength of cement-mortar incorporating palm oil fuel ash

Payam Shafigh,Sumra Yousuf,Belal Alsubari,Zainah Ibrahim Techno-Press 2023 Advances in concrete construction Vol.15 No.3

Palm oil fuel ash (POFA) is a newly emerging pozzolanic material having high amount of silica content. Various forms of POFA were used in cement-based materials (CBMs) in replacement of cement in different dosages of low and high volume. Although, there are many researches on POFA to be used in concrete and mortar, however, this material was not practically used in the construction industry. Engineers and designers need to be confident to use any new developed materials by knowing all engineering properties at short and long terms. As durability concern, concrete pH value is one of the most important properties. Portland cement produces are alkaline initially, however, it may be reduced due to aging and its components. It is believed that by incorporation of supplementary cementitious materials in CBMs the pH value reduces due to utilization of Ca(OH)₂ in pozzolanic reaction. This study is the first attempts to understand the pH value of mortars containing up to 30% POFA under different curing conditions and its changes with time. The results were also compared with the pH of ground granulated ballast furnace slag (GGBFS) and fly ash (FA) content mortars. In addition, the compressive strength of different mortars under different curing conditions were also studied. The results showed that the pH value of control mix (without cementitious materials) was more than all the blended cement mortars indifferent curing conditions at the same ages. However, there was a reducing trend in the pH value of all mortar mixes containing POFA.