Afidah Abu Bakar

Ultimate Strength of Kekatong Glued Laminated Timber Railway Sleepers

Pre-stressed concrete (PSC) sleepers are the main components of railway track systems in Malaysia. However, there are sections in the track system which PSC sleepers cannot be utilized, where timber sleepers are still needed. Due to limited supply of large sections timber logs and high cost in high grade timber, an alternative for this timber product is needed. Thus, this study is conducted to determine the ultimate strength of the alternative timber product which is glued laminated (glulam) timber railway sleepers from selected Malaysian tropical heavy hardwood timber species namely Kekatong. The static bending test at rail seats was carried out in order to achieve the objective and the test is accordance to AREMA Manual. The values of modulus of rupture (MOR) and modulus of elasticity (MOE) for two numbers of glulam timber sleepers were evaluated and compared with the MOR and MOE values of two numbers of solid timber sleeper. Then the properties are verified with the minimum performance requirement in AREMA Manual. The results showed the glulam Kekatong timber railway sleepers met the requirement set by AREMA with the static yield load surpassed the Keretapi Tanah Melayu Berhad (KTMB) specific design load.

Harmonic Formulation of Prestressed Concrete Sleeper Subjected to Freight Train

In Malaysia, rail transportation has become an integral part of the society. It can be seen by the effort of the Malaysia Government to improve the rail system by laying new route, provide new type of trains and others. For transporting goods, Malaysian rail authorities (Keretapi Tanah Melayu Berhad) used 22 coaches so-called freight train becoming one of the most popular transportation in delivery goods. In the past, wood is commonly used as a material in sleeper’s manufacturing but nowadays, prestressed concrete sleeper starts to capture their name in the industry in producing more quality sleeper as one of railway track components. This study will be focusing on determination of constant amplitude for 22 coaches, cyclic counting strain and calculation of frequency of strain on prestressed sleeper subjected to freight train. Rainflow cyclic counting method is used to determine the constant amplitude, cycle and frequency for each parts of train body. By using rainflow method and formulas, average number of cycle and frequency is obtained. From the obtained results, the individual PCS have to endure a maximum frequency and number of cycles of 11.91 Hz and 1.39 s, respectively. The outcome of this study will have a formulation of the freight train that is currently being used in Malaysia.

Flexural performance of steel fiber reinforced concrete (SFRC) ribbed slab with various topping thicknesses

Ribbed slab provides lighter slab than an equivalent solid slab which helps in reducing the weight with its voids. However, in order to overcome the drawbacks in the construction process, the application of steel fibre reinforcement concrete (SFRC) is seen as an alternative material to be used in the slab. This study is performed to investigate the behaviour of SFRC as the main material in ribbed slab, omitting the conventional reinforcements, under four-point bending test. Three equivalent samples of ribbed slabs were prepared for this study with variations in the topping thickness of 100, 75 and 50 mm. The flexural strength of ribbed slab with 100 mm topping shows similar loading carrying capacity with the 75mm topping while 50 mm gave the lowest ultimate loading. First cracks for all slabs occurred at the topping. The cracks began from the external ribs and propagates toward the internal rib. Incorporation of steel fibres help in giving a longer deflection softening than a sudden brittle failure, thus proves its ability to increase energy absorption capacity and improving cracking behaviour.Ribbed slab provides lighter slab than an equivalent solid slab which helps in reducing the weight with its voids. However, in order to overcome the drawbacks in the construction process, the application of steel fibre reinforcement concrete (SFRC) is seen as an alternative material to be used in the slab. This study is performed to investigate the behaviour of SFRC as the main material in ribbed slab, omitting the conventional reinforcements, under four-point bending test. Three equivalent samples of ribbed slabs were prepared for this study with variations in the topping thickness of 100, 75 and 50 mm. The flexural strength of ribbed slab with 100 mm topping shows similar loading carrying capacity with the 75mm topping while 50 mm gave the lowest ultimate loading. First cracks for all slabs occurred at the topping. The cracks began from the external ribs and propagates toward the internal rib. Incorporation of steel fibres help in giving a longer deflection softening than a sudden brittle failure, thus ...

Flexural strength and behaviour of SFRSCC ribbed slab under four point bending

An experimental investigation was carried out to study the ultimate strength and behaviour of SFRSCC ribbed slab under four point bending. Comparison was been made between ribbed slab that was fully reinforced with steel fibres (SFWS) with conventionally reinforced concrete ribbed slab (CS and CRC). The volume fraction of the 35 mm hooked end steel fibres used in the mix was 1% (80 kg/m3) with the aspect ratio of 65. Three full scale slab samples with the dimension of 2.8 x 1.2 m with 0.2 m thickness was constructed for the purpose of this study. The slab samples was loaded until failure in a four point bending test. As a whole, based on the results, it can be concluded that the performance of the steel fiber reinforced samples (SFWS) was found to be almost equivalent to the conventionally reinforced concrete ribbed slab sample (CRC).An experimental investigation was carried out to study the ultimate strength and behaviour of SFRSCC ribbed slab under four point bending. Comparison was been made between ribbed slab that was fully reinforced with steel fibres (SFWS) with conventionally reinforced concrete ribbed slab (CS and CRC). The volume fraction of the 35 mm hooked end steel fibres used in the mix was 1% (80 kg/m3) with the aspect ratio of 65. Three full scale slab samples with the dimension of 2.8 x 1.2 m with 0.2 m thickness was constructed for the purpose of this study. The slab samples was loaded until failure in a four point bending test. As a whole, based on the results, it can be concluded that the performance of the steel fiber reinforced samples (SFWS) was found to be almost equivalent to the conventionally reinforced concrete ribbed slab sample (CRC).

Monitoring of Precast Prestressed Concrete Beam due to Static Load by Using Pundit Equipment

The vast growt of population now increases the usage of buildings and infrastructures especially for concrete bridge. Prestressed concrete was introduced to be used in most concrete bridge superstructures. Predetermination of concrete strength ensures the condition of precast prestressed concrete structures. Testing of precast concrete is crucial in order to find its capabilities before commencing construction. Conventional method of testing usually takes a lot of time and is very costly. The aim of this study is to find the speed of the sound wave passing through the precast prestressed concrete beam. This study also identifies the shear modulus and the elastic modulus of precast prestressed concrete beam after the application of bending test on the two rectangular beams of 4 m length each. The test result indicates the condition of the beam, before and after loading condition. The ultrasonic pulse velocity (UPV) method is an ideal tool to show whether concrete structure is in good condition. This method can be used for those still been constructed and on existing structures. Interpretation of velocities using UPV method could easily determine the grading in terms of its uniformity and strength. The velocities indicate the occurrence of voids inside the beam which relates to the tendency of initial failure. Decreases in ultrasonic waves speed over time can reveal the onset of damage before visible deficiencies become evident. This allows inspectors and engineers to implement repair recommendations before minor deficiencies become safety hazards.

Serviceability of Construction Materials Under Tropical Climate Effects

The key aspect discussed in this study is the serviceability of the construction materials namely concrete and steel under the tropical climate effects. The environmental effects such as the temperatures, chemicals from the rain, and particles brought by the wind can cause corrosion on the concrete surface and thus may affect a structure’s performance. Through this study, the extent durability of the construction materials was investigated in order to know how far the strength can be affected by the nature. Fifteen concrete cubes and fifteen numbers of steel rods were prepared and placed in two different areas; one is an area which has room temperature surrounding while the other is exposed to the tropical climate for a period of 3, 6, 9, and 12 months. Once the exposure time has lapsed, compression test was done to test the mechanical properties of the concrete cubes while the steel reinforcement underwent the tensile test. After the test was done, it was shown that the control samples of both concrete cubes and steel reinforcements are more durable and stronger compared to its counterpart that was placed in the exposed areas.

Post-fatigue Behaviour of Kekatong Glued Laminated Timber Railway Sleepers

The availability of good quality timber log is limited as well as the depleting supply of wide width and long-length structural-grade timbers caused increase in price. However, the usage of timber sleeper is significant to certain location in the track system. Consequently, alternative to replace existing timber sleepers to another timber product is vital and glued laminated timber (glulam) has a potential. Numerous researchers on glulam timber sleeper are focusing on the performance of static flexural study. However, the performance of glulam sleepers under the flexural fatigue is less known. Thus, this study leads to conduct flexural fatigue test in order to identify fatigue resistance of timber sleepers and investigate its behaviour. In addition, this study is carried out to determine the residual strength of timber sleepers after imposed with cyclic loading. A series of test were performed to determine the fatigue performance in accordance with the America Railway Engineering and Maintenance-of-Way (AREMA) Manual. The results showed that the Kekatong glulam sleepers complied with the requirement set by the AREMA Manual and the fatigue performance and behaviour are comparable to the solid timber sleepers.

Steel Fibre Reinforced Self-Compacting Concrete (SFRSC) performance in slab application: A review

The application of Steel Fibre Reinforced Self-compacting Concrete (SFRSC) in the construction of structural elements is seen as an alternative solution to the complication in placing the reinforcement and compaction of normally vibrated concrete. The main advantage of SFRSC is the ability to be properly poured in place, filling the formwork corners and small voids between reinforcement bars by means of its own weight. Many research had been done in exploring the structural performance of SFRSC due to the enhanced engineering and mechanical properties. The incorporation of steel fibres in the mix has been found to enhance the hardened properties of self-compacting concrete in terms of its tensile strength, ductility, toughness, energy absorption capacity and as well as fracture toughness. The objective of this paper is to review the work done by previous researchers on the performance of SFRSC in slab structures. The knowledge could be used as a guide in expanding the application of SFRSC as the main mate...

Bending Strength of Pre-tensioned (PRT) Concrete Beam

This paper presents a preliminary study on bending strength of pre-tensioned (PRT) concrete beam as the experiment result can be used in maintenance planning. The production of beam was according to BS8110, BS4449:2005 and BS5896 for concrete, reinforcement bar and strand, respectively. For the bending test, theoretically and practically was conducted in accordance to BS5400 standard. The result showed cracked beam retrofitted with fiber reinforced polymer (FRP) plate and carbon fiber reinforced polymer (CFRP) sheets are able to increase the bending strength of beam up to 43 and 42 %, respectively.