Mohd Hisbany Mohd Hashim

Retrofitting of Single Unit Tunnel Form Building Using Steel Plate under Out-of-Plane Lateral Cyclic Loading

A one-third scale single unit of 3-storey tunnel form building with foundation beam was designed, constructed and tested under out-of-plane lateral cyclic loading. This building was designed according to BS8110 with no provision for seismic loading. Tunnel form building was initially tested at ±0.01% , ±0.1%, ±0.25%, ±0.5%, ±0.75%, ±1.00%, ±1.25% and ±1.5% drifts until the structure lost its lateral strength (strength degradation). Then, the specimen was repaired and retrofitted using steel plate and angle which was positioned at the wall-slab joints that had suffered severe damages. A similar drift of displacement before retrofitting was repeated for the specimen after being retrofitted. Visual observation of damages, hysteresis loops, stiffness, ductility and equivalent viscous damping (EVD) of the specimen were analyzed and compared before and after retrofitting. The proposed retrofitting technique has increased its lateral strength by 26%. Fewer cracks occurred after retrofitting the specimen compared to before retrofitting. It can be concluded that steel plate and angle can strengthen the wall-slab joint and this method can be used to retrofit the tunnel form building if it had been damaged caused by earthquake excitations.

Comparison of Seismic Behaviour for a Single Unit Tunnel Form RC Building before and after Repaired

Repairing and strengthening the structures are gaining more attention from many researchers and structural engineers after the structures suffered damages from natural disasters. Tunnel form RC buildings which are not designed according to seismic code of practice are very vulnerable to ground motion when located to near field earthquake. This paper presents the method of repair and strengthening of 3-storey tunnel form building subjected to in-plane lateral cyclic loading. The building was strengthened using the combination method of steel angle, steel plate and Carbon Fiber Reinforce Polymer (CFRP) sheet. The results show that the lateral strength capacity is increase by 15.66%, ductility increase by 53.57% and equivalent viscous damping increase by 28.88% for the first cycle and 33.65% for the second cycle. However, the stiffness of the structure reduce by 56.6%. It can be concluded that this method can be adopted for the damage of tunnel form building system.

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).

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.

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...

Density Assessment of Heat Treated Malaysian Hardwood Timber: The Case of Kapur (Dryobalanops spp.) and Keruing (Dipterocarpus spp.)

Heat treatment is one of the environmental friendly ways to treat timber that will lead to the improvement of timber natural quality and equip the timber with new properties. It is an eco friendly and alternative treatment method that will modify the properties of timber by using high temperature instead of using chemical preservatives as common practice. This paper presents the effect of heat treatment on physical properties which is density for two types of Malaysia hardwood namely kapur and keruing. Specially design electronic furnace was used as an oven for the heat treatment process. The result shows a reduction in density after heat treatment, however the difference is not merely significant. Lower in density indicates a weight loss which theoretically caused by moisture content loss thus leading to the increment of movement stability.

Assessing the Flexural Performance of RC Beams with Application of Glass Fiber Reinforced Polymer (GFRP) Bars

This study investigated the flexural performance of RC beams reinforced and strengthened with Glass Fiber Reinforced Polymer (GFRP) bars. Tropical climate effects such as heat and rain throughout the year may cause the concrete surface to gradually erode and it may expose the steel inside the beam. If the steel is exposed, it may be oxidized and thus decreasing the strength of the RC structure. To avoid this situation from happening, reinforcing and strengthening method may be applied as an alternative as it is believed to be able to increase the durability of the structure. Three beams were constructed in this study. The first beam is a control beam. Second is a beam that longitudinally reinforced with steel at compression and GFRP bars at tension. The third beam is a beam reinforced with steel and strengthened by NSM method with GFRP bar at the tension zone. All three beams have the same dimension of 125mm × 300mm × 1800mm (width; height; length). All three beams were subjected to flexural test under four point static loads until failure. The result shows that the beams reinforced and strengthened with GFRP bars were seen to have higher stiffness compared to the control beam by 8% and 16% respectively. This proves that reinforcing and strengthening the RC members using FRP material can significantly improve the flexural capacity.