Fadzli Mohamed Nazri

UHPFRC as Repair Material for Fire-Damaged Reinforced Concrete Structure – A Review

Exposure of concrete to intense heat will cause deterioration of its strength and durability. Previously, the fire-damaged concrete was repaired using the shotcrete and normal concrete. Recent studies utilize fibre reinforced polymer (FRP) in repairing fire-damaged concrete. Ultra High Performance Fiber Reinforced Concrete (UHPFRC) mostly developed using fine size aggregate, cement, silica fume, super plasticizer and reinforced with steel fibre has an excellent mechanical properties compared to high strength concrete and with an addition of steel fibre in the UHPFRC enhances its ductility behaviour which is not possessed by normal concrete, hence, UHPFRC indicates a promising candidate as repair material to fire-damaged concrete. The aim of this paper is to review on the properties of UHPFRC to be utilized as repair material to fire-damaged concrete structure based on previous research on UHPFRC and fire-damaged structure.

Nonstructural Damages of Reinforced Concrete Buildings Due to 2015 Ranau Earthquake

On 15th June 2016 a moderate earthquake with magnitude Mw5.9 was occurred in Sabah, Malaysia. Specifically, the epicentre was located at 16 km northwest of Ranau. Less than two days after the first event, a reconnaissance mission took action to investigate the damages on buildings. Since the reinforced concrete buildings in Ranau were designed based on gravity and wind load only, a lot of minor to severe damages was occurred. This paper presents the damages on the nonstructural elements of reinforced concrete buildings due to Ranau earthquake. The assessment was conducted via in-situ field investigation covering the visual observation, taking photo, and interview with local resident. Based on in-situ field investigation, there was a lot of damages occurred on the nonstructural elements like the brick walls. Such damages cannot be neglected since it can cause injury and fatality to the victims. Therefore, it can be concluded that the installation of nonstructural elements should be reviewed for the sake of safety.

Predicting collapse loads for buildings subjected to seismic shock

In this paper an analytical expression that estimates the collapse load of a generic class of multi-storey, uniform, moment-resisting steel frames is presented. This expression is validated and calibrated with nonlinear pushover analyses (NPA) and incremental dynamic analyses for a set of buildings, of differing heights, that are designed according to the Eurocodes. The efficacy of different seismically induced load profiles in NPA is discussed with a preferred profile suggested for this class of structural system. The relationship between the actual seismic force reduction factor and code specified behavior factors is underlined.

Performance of MRFs Due to Nonlinear Analysis

Pushover analysis (POA) was carried out on six different types of frames. In this analysis, lateral load acts as the main role in evaluating the structure performance according to the pushover analysis. In this analysis, as suggested by Eurocode 8 (BSI in Eurocode 8: design provisions for earthquake resistance of structures: part 1-1, general rules—seismic actions and general requirements for structures. British Standards Institution, London, 2004), the triangle lateral load was applied to perform the analysis.

Moment-Resisting Frames (MRFs)

In this section, six sets of model moment-resisting frames (MRF) were analyzed with different types of geometry (regular and irregular frames), material, and heights. These frames abide by the Eurocodes (EC).

Permeability and Strength of Porous Concrete Paving Blocks at Different Sizes Coarse Aggregate

Porous concrete paving block (PCPB) is a block with continuous voids which are intentionally incorporated into concrete. The permeability and strength of PCPB with different sizes of coarse aggregate was presented in this study. Three different sizes of coarse aggregate were used; passing 10 mm retained 5 mm (as Control), passing 8 mm retained 5 mm (CA 5 – 8) and passing 10 mm retained 8 mm (CA 8 – 10). Furthermore, a series of test were conducted in this study such as compressive strength, porosity and permeability. It was found that the size of coarse aggregate affects the strength and porosity of the specimens. It was also shown that PCPB with CA 8 – 10 resulted in low strength, but high in porosity and permeability compared to the other blocks. Beside that PCPB using CA 8 – 10 is able to remove surface runoff efficiently.

Strength and properties of concrete pavement incorporating multiple blended binders

This study investigated the effects of multiple blended binders on the properties and performance of concrete pavement. Mineral admixtures, namely, silica fume, metakaolin, and rice husk ash, are used to replace ordinary Portland cement at replacement levels of 0% (control mix), 5%, 10%, and 15% by mass-to-mass basis. The performance of the multiple binders on the concrete pavement properties was evaluated based on compressive strength, strength reduction, and strength activity index. Results showed that the mineral admixtures can be satisfactorily used as cement replacement materials to increase the properties of pavement concrete. Moreover, concrete pavements with 5% and 10% replacement levels exhibited excellent performance with good strength.

Soft storey effects on plastic hinge propagation of moment resisting reinforced concrete building subjected to Ranau earthquake

On 5th June 2015, a moderate earthquake with Mw 5.9 hit Ranau, resulted in damages of the existing nonseismically designed buildings, such that 61 buildings, including mosques, schools, hospitals and Ranau police headquarters were suffered from different level structural damages. Soft storey irregularity is one of the main reasons of the building damage. This study is to investigate the soft-story effect on the propagation path of plastic hinges RC building under seismic excitation. The plastic hinges formation and seismic performance of five moment resisting RC frames with different infill configurations are studied. The seismic performance of building is evaluated by Incremental Dynamic Analysis (IDA). Open ground soft storey structure shows the lowest seismic resistance, collapses at 0.55g pga. The maximum interstorey drift ratio (IDRmax) in soft storey buildings ranging from 0.53% to 2.96% which are far greater than bare frame ranging from 0.095% to 0.69%. The presence of infill walls creates stiffer upper stories causing moments concentrate at the soft storey, resulting the path of plastic hinge propagation is dominant at the soft storey columns. Hence, the buildings with soft storey are very susceptible under earthquake load.

Effects of heating durations on normal concrete residual properties: Compressive strength and mass loss

This study investigates the effects of high temperature with five different heating durations on residual properties of 30 MPa normal concrete. Concrete cubes were being heated up to 600°C for 30, 60, 90, 120 and 150 minutes. The temperature will keep constant for 30, 60, 90, 120 and 150 minutes. The standard temperature-time curve ISO 834 is referred to. After heating the specimen were left to cool in the furnace and removed. After cooling down to ambient temperature, the residual mass and residual compressive strength were observed. The obtained result shows that, the compressive strength of concrete decrease as the heating duration increases. This heating duration influence, might affects the loss of free water present and decomposition of hydration products in concrete. As the heating duration increases, the amount of water evaporated also increases led to loss in concrete mass .Conclusively, the percentage of mass and compressive strength loss increased as the heating duration increased.

The optimum content of rubber ash in concrete: flexural strength

Discarded scrap tyres have become one of the major environmental problems nowadays. Several studies have been carried out to reuse waste tires as an additive or sand replacement in concrete with appropriate percentages of tire rubber, called as rubberized concrete to solve this problem. The main objectives of this study are to investigate the flexural strength performance of concrete when adding the rubber ash and also to analyse the optimum content of rubber ash in concrete prisms. The performance total of 30 number of concrete prisms in size of 100mm x 100mm x 500 mm were investigated, by partially replacement of rubber ash with percentage of 0%, 3%, 5%, 7% and 9% from the volume of the sand. The flexural strength is increased when percentage of rubber ash is added 3% from control concrete prism, RA 0 for both concrete prism age, 7 days and 28 days with value 1.21% and 0.976% respectively. However, for RA 5, RA 7 and RA 9, the flexural strength was decreased compared to the control for both age, 7 days and 28 days. In conclusion, 3% is the optimum content of rubber ash in concrete prism for both concrete age