HILTON AHMAD
@uthm.edu.my
ASSOCIATE PROFESSOR
UNIVERSITI TUN HUSSEIN ONN MALAYSIA
EDUCATION
Bachelor of Civil Engineering (Universiti of Malaya)
PhD in Structures and Materials Engineering (University of Surrey)
RESEARCH, TEACHING, or OTHER INTERESTS
Civil and Structural Engineering, Computational Mechanics, Mechanics of Materials, Ceramics and Composites
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Chia Lia Yip, Sugiman Sugiman, Desmond Chin, and Hilton Ahmad
Elsevier BV
Khairi Supar, Hairuddin Mohammad, Masiri Kaamin, Mohamad Azim Mohammad Azmi, Mohd Kamaruzaman Musa, Mohammad Ashraf Abdul Rahman, Hilton Ahmad, and J. Toby Mottram
Akademia Baru Publishing
Cement mortar offers an excellent replacement for materials such as fine aggregate with tire rubber waste in the form of crumbs. It provides excellent environmental and technical benefits to concrete production using recycled materials. As such, it contributes to the sustainable development of the construction industry. This paper mainly emphasizes the strength of untreated and treated crumb rubber from waste tires in cement mortar. Crumb rubber that has been pre-treated with Silica fume (SF) and sodium hydroxide (NaOH) to improve the strength of the mortar mix. This research used a cement-aggregate mix ratio of 1:4 and a water-cement ratio of 1:2. Five different percentages of fine aggregate replacement (0, 3, 6, 9, and 12%) was selected. The compressive strength, density, and water absorption of the mortar were measured at 28 days to find optimum strength. The compressive strength of the cement mortar mixed with treated crumb rubber showed significantly higher values, with an increase of 92% for 12% treated crumb rubber by sodium hydroxide (TN12) compared to untreated crumb rubber. The density value of the mortar cube mixed with treated crumb rubber decreased when the percentage of replacement for treated crumb rubber increased. In the application of roof tiles, lower density values provide an advantage for workability during installation. For water absorption, the treated crumb rubber contributes to a lower percentage of water absorption (acceptable until 6% for SF and 9% for NaOH) compared to the control sample as untreated crumb rubber. Therefore, a mixture of mortar with treated crumb rubber, especially NaOH solution, is better than the untreated crumb rubber specimen.
Collin Fong, Sugiman Sugiman, Desmond Chin, and Hilton Ahmad
Informa UK Limited
M. R. Maulana, S. Sugiman, H. Ahmad, Z. M. Jaini, and Hazrina Mansor
Springer Science and Business Media LLC
Malik Ridwan Maulana, Hilton Ahmad, and Sugiman Sugiman
MDPI AG
This study examined the fracture and failed performance of foamed concrete materials by testing normalized notched beams under three-point bending via three methods: inverse analysis, digital image correlation (DIC), and finite element modeling (FEM). It also discussed both experimental and FEM characteristics. However, inverse analysis is only applicable for specimens with a notch height of 30 mm. Bilinear softening of the tested beams was estimated to identify the fracture energy (GF), critical crack length (ac), and elastic modulus (E). Additionally, the fracture toughness was calculated by adopting the double-K method (initiation fracture, unstable fracture, and cohesive fracture). Two-dimensional FEA modeling of the fracture was conducted using the traction-separation law (TSL), incorporating the extended finite element method (XFEM) and cohesive zone (CZM) techniques. A finite element sensitivity for the XFEM and CZM was performed, with the global mesh size of 2 and the damage stabilization cohesion of 1 × 10−5 showed good convergence and were used in other models. Further comparison of the DIC experiment findings with those from the FEM demonstrated good agreement in terms of crack propagation simulation.
Zaim Omar, Sugiman Sugiman, Hazrina Mansor, and Hilton Ahmad
Elsevier BV
Collin Fong, , Desmond Daniel Chin, Hilton Ahmad, , and
Penerbit UTHM
Eggshells are daily food waste disposed of in landfills, producing environmentalissues and an unpleasant odour. Eggshells were crushed to form eggshell powder and may be suitably applied as a filler in epoxy resins to improve their mechanical properties. The shear strength of toughened epoxy with eggshell powder (TEEP) wasstudied. Single-lap joint (SLJ) sheartests were conducted toinvestigate the shear strength of the SLJbonded with different volume fractionsof TEEP. For this purpose, the eggshells were dried and crushed into particles of size 150μm. The volume fraction of eggshell powder in the epoxy resin is 0%, 2.5%, 5%, and 10% by epoxy weight. The epoxy resin system was made of EPIKOTE Resin 828 and Hardener 651 with a mixing ratio of 5:2 by weight.The results show that the shearstrength greatly depended upon overlap lengthand filler volume fractions.The improvement was up to 72.7% and 39.9%,with the longest overlap length and 5% TEEP fraction.Hence, an overlap length of 38.1 mm and a 5% eggshell volume fraction gave the optimum shear strength of 5.045 kN.
C.L. Yip, , H.M. Mohamad, H. Ahmad, , and
Penerbit UTHM
Fracture energy is regarded as an intrinsic (material) properties that dominates crack mechanisms and associated crack growth in concrete damage under applied stress. In recent times, significant advancements in computing technology have driven the adoption of finite element analysis (FEA) methodologies that necessitate the integration of constitutive models, includingthe traction-separation relationship derived from cutting-edge fracture mechanics. A physically-based model requires fracture energy values; therefore, a properly measured fracture energy value is essential to exhibit better structure response within FEA models. There are large arrays of parameters involved during the concrete mixture, such as beam size effect, aggregate size, and concrete grade, that affect the flexural resistance of the concrete. The fracture and failure in concrete ahead of the crack tip are represented by fracture energy values where micro-damage events such as interfacial failure, fiber-bridging, and matrix cracking occurred.This study aims to determinethe fracture energy of concrete specimens with combination of notch depth aoat mid-span, design concrete strength as specified in the testing series. Independent compression strength, fcand measured load-displacement profiles underathree-point bendingtest were used to determine fracture energy by incorporating three available fracture energy expressions such as Bazant, Hillerborg,and CEB-FIP models.
Zaim Omar, Sugiman Sugiman, Mustafasanie M. Yussof, and Hilton Ahmad
Elsevier BV
Ummu Salamah Md Tahir, , Noor Yasmin Zainun, Hilton Ahmad, Shabir Hussain Khahro, Ahmad Rizal Alias, , , , and
Penerbit UTHM
Food waste is one of the critical issues which has been discussed in many countries including Malaysia. Apart from that, about 50% of food waste usually being dumped at landfill sites and incinerators which root to more problems towards the environment, economic and society. In this research, Taman Pura Kencana, Johor was chosen to identify the average total of food waste generation from selected households in 3 months from April 2021 to June 2021and to determine decomposing days of food waste using BSFL.Raosoft Sample Size Calculator was used to calculate sample respondents bringing 48 households in this research. Hence,the average total of food waste generation from households per month was1056.82 kgThe collection of food waste from selected households in Taman Pura Kencana during the normal month of June was the highest compared to the fasting month in April and Eid month in May.25samples of food wastewere examined to identify duration of decomposing daysusing BSFLbased on pH, temperature and moisture content.The results showed that, the food waste successfully decompose after 10 days compare to control sample whichwas taking the longest time to fully decompose at about 90 days.The range of average temperature of the food waste using BSFL were 27°C to 34°C.The initial range of average pH value for the food waste samples were 3.22 to 4.00 while on the last decomposing days of the food waste samples were 7.06 to 7.12.Moisture content for food waste samples is51% except for control sample.Inconclusion, BSFL werethe ideal insects to decrease amount of food waste in landfills and incinerators as they could accelerate the time of composting food wasteand could reduce the negative impacts towards the environment, economic and society.This research’s findings will help create awareness and a better understanding of how much food waste could be generated from residential area, as this contributes to many negative issues when discarding them through landfills and incinerators.
Malik Ridwan Maulana, Sugiman Sugiman, Hilton Ahmad, Zainorizuan Mohd Jaini, and Hazrina Mansor
FapUNIFESP (SciELO)
Syed Ahmad Hakim Bin Syed Muzamil, Noor Yasmin Zainun, Nadiatul Nazleen Ajman, Noralfishah Sulaiman, Shabir Hussain Khahro, Munzilah Md. Rohani, Saifullizan Mohd Bukari Mohd, and Hilton Ahmad
MDPI AG
Floods have been reported to be an important disaster in any country and Malaysia has faced similar disasters in the past, resulting in disturbance in daily community routine issues, financial losses, infrastructure damage including railway tracks, bridges, roads, vehicles, properties, and the worst is the loss of lives. The Sarawak region of Malaysia also witnesses yearly disasters in rainy seasons. The purpose of this paper is to explore the possible challenges to manage the flood disaster in Sarawak and to identify the possible solutions to manage floods. In this research, secondary data was used for qualitative assessment. The newspaper articles were collected from the year 2015 until 2019. Targeted interviews were conducted with experts working in flood management disaster schemes to rank and validate the most important factors after content analysis from the past news reports. It is concluded that poor drainage systems, rapid development, heavy rainfall, lack of public awareness, and lack of coordination in executing the disaster management cycle among agencies are the key challenges. Thus, it is recommended that the drainage systems should be upgraded in the case study area. Proper flood management schemes should be planned and flood forecasting should be strengthened. An effective early flood warning system should be designed to activate the plans and a proper public awareness campaign should be initiated to educate and train the local community to deal with such disasters. It is also suggested to assure and maintain proper collaboration among different agencies during such disasters. In the last phase, this paper also proposes a framework for future flood disaster management. The framework will assist the stakeholders to make informed decisions to save human lives and substantial financial losses. The framework can also be used in similar terrain countries.
Malik Ridwan Maulana, , Hilton Ahmad, Hazrina Mansor, , and
Penerbit UTHM
This study concentrates on FEA modelling of concrete beam strengthened with externally bondedCFRP lates under bending by using Traction Separation Law (TSL) as constitutive law to require maximum cohesive stress and fracture energy values. The FEA models were developed following experimental work reported by Al-Rousan et al. [23] and Ding et al. [22]. Combination of two numerical techniques were adopted, i.e., Extended Finite Element Method (XFEM) and Cohesive Zone Method (CZM) assigned within cracked beam region and adhesive layer respectively. The consistence of FEA beam deformations to capture debonding failure as seen during experimental observations and load-displacement was evaluated accordingly. Additionally, combination of XFEM-CZM techniques provides good strength predictions with experimental dataset. It is clearly shown that the failure mode exhibited are determined by testing method, CFRP width and CFRP length. CFRP sheets provides a significant contribution to concrete ductility, which is noticeable in longest CFRP sheet. All testing series were examined, the discrepancies of less than 25% were found. Note that current approach used calibrated fracture energy values from similar concrete grade and CFRP plates, however better prediction can be produced if fracture energy values were independently determined from experimental set-up.
Hilton Ahmad and Noor Yasmin Zainun
Springer Nature Singapore
Nadiatul Nazleen Ajman, Noor Yasmin Zainun, Noralfishah Sulaiman, Shabir Hussain Khahro, Farid Ezanee Mohamed Ghazali, and Mohd Hilton Ahmad
MDPI AG
A stable methodology for conserving the natural environment has been a concern for developing countries. The fast-paced growth of urbanization generated significant demand for automobiles, leading to greater utilization of fuel. The consumption of fuel is fulfilled by the Filling Station (FS). An FS is undoubtedly an important facility, but it is reported that it has high potential for degradation of natural resources, pollution problems, environmental degradation, and hydrological, geological, and socio-economic hazards, and therefore the site selection of such facilities is an essential problem. The traditional approach utilizes EIA assessments and GIS separately and existing models lacks integration. Thus, this study provides an integrated GIS-based land suitability modeling using EIA assessments, and the Analytic Hierarchy Process (AHP) has been used as key land use feature prioritization for the appropriate selection of FS locations. A case study is also carried out to assess the precision of the suggested model. The findings indicate that more than 73% of the present FS are in the acceptable region, while 27% of the FS are not in the adequate region using the local code. Furthermore, 58% of the present FS are in the acceptable region, while 42% of current FS are not in the adequate region using the international code. The findings of the comparative code analysis show a difference in the codes. The international code looks safer compared to the local code because it has higher buffer distances. This model will assist decision-makers in making better decisions for such land suitability problems for filling stations, and this model can also be extended to other facilities by some modifications in the filters and data layers of the model.
H. Ahmad, S. Sugiman, Z.M. Jaini, and A.Z. Omar
FapUNIFESP (SciELO)
H. Ahmad, S. Sugiman, and N.Y. Zainun
FapUNIFESP (SciELO)
H. Ahmad, S. Sugiman, and N.Y. Zainun
FapUNIFESP (SciELO)
The current paper aimed to model failures and fractures in single-lap bolted joints of woven fabric kenaf fiber reinforced polymer (KFRP) composite plate to fail in net-tension. The approach was based on the assumptions that micro-damage events were densely concentrated ahead of the notch tip and crack growth were readily seen along net-tension plane in a self-similar fashion. A 3-D finite element modelling framework were developed to explicitly incorporate bolt clamp-up in a range of KFRP series following tested experimental datasets. Lay-up types, normalized W/d, temperature exposure with constant bolt torque of 5 Nm were considered. It was found that KFRP plates under elevated temperature were stronger than under room temperature due to matrix toughening. Traction-separation relationship was incorported within Extended Finite Element Method (XFEM) framework to model damage within KFRP composite plate by using independent experimental datasets, here incorporates un-notched plate strength, σo and fracture toughness, Gc of all testing lay-ups. Constitutive model used is associated with stress concentration, therefore good agreement between predicted and experimental bearing stress at failure with net-tension failure mode is perhaps not suprising.
Sugiman Sugiman, Paryanto Dwi Setyawan, Salman Salman, and Hilton Ahmad
Elsevier BV
Lee Sim Yee and Hilton Ahmad
Informa UK Limited
ABSTRACT The present paper aims to predict the bearing stress at failures of woven fabric kenaf fibre reinforced polymer with single-lap hybrid joints under quasi-static testing. Testing series investigated includes a variation of joint types, normalised W/d, lay-up types, plate thickness and bolt loads. Initially, cohesive failures appeared within adhesive layer, followed by net-tension failure mode in all testing series investigated associated with stress concentration. Strength prediction was carried out subsequently by implementing XFEM framework with an embedded traction-separation relationship within ABAQUS CAE. The experimental datasets and XFEM results were evaluated where good agreements were found in the combination of cross ply and thicker coupon with a discrepancy of less than 5%.
Khairi Supar, Hilton Ahmad, and Mustafasanie M. Yussof
FapUNIFESP (SciELO)
Multi-bolted joints are adopted and designed to provide efficient load transfer within assembled engineering parts. Bearing failure is favorable during design phase due to more progressive failure mode, however, ability of by-pass stress to be transferred to adjacent bolts in multi-bolted joints prone to catastrophic net-tension failure. Former approach known as equivalent spring stiffness (ESS) was proposed but it requires experimental sliding load value. This has led to semi-empirical approach to require experimental set-up than incorporating a generic bolt preload value. This paper aims to provide a unified bolt preload (UBP) value to be implemented in each bolt independent upon plate properties and bolts arrangements. Strength prediction were taken place by 3-D Extended Finite Element Method (XFEM) framework of various staggered and non-staggered arrangements to include various lay-ups types and plate thickness. The failure loads predictions in each testing series were investigated and then validated against experimental datasets and also compared with previous technique (ESS approach). Crack patterns and failure modes from this approach were consistent with experimental observations, where net-tension failures were observed within all testing series. Less good prediction compared to from ESS technique, partly due to semi-empirical nature in former approach. Nevertheless, reasonable agreement in UBP technique with experimental datasets were obtained (average discrepancy of approximately 20%).
K. Supar, , H. Ahmad, and
Universiti Malaysia Pahang Publishing
A study on structures response in multi-holes plates is important to understand the effect
of neighbouring hole on stress concentration as subjected to tensile loading prior to
bearing failure in multi-bolted joints. Current work implemented experimental
framework on staggered and non-staggered multi-holes configurations to include
various lay-up types, plate thickness and hole configurations as specified in the testing
series. Experimental observations found that all configurations failed in net-section path
suggesting that fracture initiates and propagates from the notch tip perpendicular to
loading direction in self-similar fashion through the plate thickness. Non-staggered hole
configurations demonstrated peak load compared to staggered counterparts due to more
congested holes in staggered configurations. Two-dimensional Extended Finite Element
Method (XFEM) modelling framework was carried out in all configurations
investigated by sufficient meshing refinements, damage stabilization value and
boundary conditions. XFEM was extended from classical finite element expression
which has enriched function to enable the crack be tracked visually. A physically-based
constitutive model from traction-separation relationship was applied and independently
measured material properties and in-plane elastic properties were implemented in
current work. Strength prediction results showed that good agreement was found in all
testing series and showed discrepancies of less than 15%, the best prediction in
combination of PX4 lay-ups and staggered multi-holes configurations series.