Numerical simulation of axially loaded concrete filled hollow steel section columns at elevated temperatures

Concrete filled hollow steel section columns exhibit various advantages over other materials for similar applications. These include improvement in the structural behaviour with high load bearing capacity for smaller cross-section, better appearance, rapid construction, and high fire resistance without external protection. The study of the thermal-structural behaviour of concrete filled hollow section columns has seen a gradual transition to numerical simulations over an expensive and time consuming physical tests. At present, most of the numerical tools developed in Malaysia for predicting the behaviour of structure in fire is carried out using finite difference method which can be tedious, complicated and very sensitive to numerical errors. Thus, a three-dimensional finite element model, ABAQUS, is proposed to study thermal-structural behaviour of axially loaded concrete filled hollow steel section slender columns for circular and square cross-sections at elevated temperatures. The outer diameter of the circular columns ranged from 141.3 mm to 478 mm and the steel thickness varied from 4.78 mm to 12.79 mm. The outside width of the square columns ranged from 152.4 mm to 350 mm, while the thickness of the steel wall varied from 5.3 mm to 7.7 mm. The proposed numerical models are also ranged based on types of concrete (plain and bar-reinforced concrete), steel yield strength (284 MPa to 350 MPa), concrete compressive strength (18.7 MPa to 58.3 MPa), and thickness of external protection (7 mm to 17 mm). The parameters input used in the model are results of an extensive sensitivity analysis. The accuracy of the proposed numerical model was verified against 21 experimental results and 12 existing models carried out by other researchers as well as with the predictions of the Eurocode 4 simplified calculation model. The verified model was used for a series of parametric studies on the effect of various factors affecting the fire resistance of the columns. The proposed numerical model has proved to produce a better estimation of the fire resistance of the concrete filled hollow steel section columns than the Eurocode 4 simplified model when compared with the fire tests. Based on the analysis and comparison of typical parameters, the effect of sectional shapes, concrete types and thickness of external protection on temperature distribution and structural fire behaviour of the columns are analysed. The result shows that concrete filled hollow section column with circular cross-section has higher fire resistance than square section

Properties of cement mortar containing NaOH-treated Crumb rubber as fine aggregate replacement

In this study, crumb rubber was used to partially replaced fine aggregate in mortar mixture by 5, 10, 15, and 20 volume percentage (vol%) with untreated and NaOH-treated crumb rubber. Thus, the total number of mixtures was 9. The mortars were tested for its flowability, compressive strength, flexural strength and density. Based on the results, increasing the replacement percentage of fine aggregate by crumb rubber reduced the compressive strength, flexural strength and density of rubberized mortar but increased the flowability. Meanwhile, the treatment of crumb rubber using NaOH solution improved the flowability, compressive strength and flexural strength. The treatment has minor effect on the hardened density of the rubberized mortar

Study on the Preparation of Eggshell Powder as a Partial Cement Replacement in Mortar

This research presents the investigation on the performance of cement mortar containing different preparation methods of eggshell powder (ESP). Four (4) types of eggshell powder (ESP) were prepared as the cement replacement, including untreated air-dried eggshell powder (UAESP), untreated oven dried eggshell powder (UOESP), treated air-dried eggshell powder (TAESP) and treated oven dried eggshell powder (TOESP). The cement mortar with water to cement ratio of 0.485 were mixed with 20% of ESP by the weight of the cement. The effects of ESP were investigated in terms of flowability, compressive strength, rate of strength development and hardened density at 7 and 28 days. Compared to untreated ESP mortar, treated ESP mortar had lower flowability, higher compressive strength, better rate of strength development, and higher density. Meanwhile, the effect between air-dried and oven dried ESP on the flowability of cement mortar is insignificant. However, it was discovered that the oven dried ESP mortar had higher compressive strength, better rate of strength development, and higher density than the air-dried ESP mortar. It can be concluded that the most suitable preparation methods of ESP to be used as cement replacement is the treated oven dried (TOESP) method

Compressive strength of eco-processed Pozzolan concrete under Chloride and Sulphate exposure

Sulphate and chloride attacks on concrete are the notable issues in the field of durable concrete structures. Therefore, this study focused on the influence of Eco Process Pozzolan (EPP) ash on the strength performances of concrete exposed to sulphate and chloride environment. In this study the Ordinary Portland cement was partially replace with 10%, 20% and 30% of Eco process pozzolan ash by weight of cement and water to binder ratio of 0.45 was used in all concrete mixes. Eco process pozzolan is a solid waste generated from Spent bleaching earth after process of residual oil extraction was done. After demoulding samples were immersed in water for the curing period of 28 days. Afterwards, specimens were shifted in 3.5% Sodium chloride (NaCl) and 3.0% Sodium sulphate (Na2So4) solutions for additional curing periods of 7, 14 and 28 days. The short term effects of sulphate and chloride on the concrete were evaluated in terms of change in weight and variation in compressive strength. It was observed that the addition of EPP in concrete gives the lower loss of strength compared to the control mix when immersed in Sodium chloride and Sulphate chloride at the exposure period of 28 days. While, 10% of EPP has the lowest loss of strength compare to the other mix with EPP. This study suggests that 10% of EPP as supplementary cementitious material in concrete can reduce the negative effects of sulphate and chloride salts. The outcome of this study indicated that application of EPP as supplementary cementitious material in concrete increases the resistance against aggressive environment

Comparison of Artificial Neural Network (ANN) and Response Surface Methodology (RSM) in Predicting the Compressive Strength of POFA Concrete

This study presents a comparative study between Artificial Neural Network (ANN) and Response Surface Methodology (RSM) in predicting the compressive strength of palm oil fuel ash (POFA) concrete. The comparison was made based on the same experimental datasets. The inputs investigated in this study were percentage of POFA replacement and water-to-cement ratio. The methods employed in ANN and RSM were feedforward neural network and face-centered central composite, correspondingly. The comparison between the two models showed that RSM performed better than ANN with coefficient of determination (R2 ) closer to 1 with 0.9959. In addition, all the predicted results by RSM against the experimental results fell within 10% margin. For ANN model, however, three of its predicted results were outside the 10% margin. Percentage of POFA as cement replacement was also found to have greater impacts on the compressive strength of concrete than water-to-cement ratio. Lastly, the optimization of the proportions using RSM predicted that the maximum strength of POFA concrete is 32.19 MPa

Effect of Water-Cement Ratio on the Properties of NaOH-Treated Rubberized Mortar

In this study, crumb rubber was used to partially replaced fine aggregate in mortar mixture by 5, 10, 15 and 20 volume percentage (vol%) with untreated and NaOH-treated crumb rubber. There were three (3) different water-cement ratio used which are 0.45, 0.50 and 0.55. Thus, the total number of mixtures was 27. The mortars were tested for flowability, compressive strength, flexural strength and density. Based on the results, higher water cement ratio and percentage of crumb rubber replacement increased the flowability but lowered the density, compressive strength and flexural strength of the rubberized mortar. It was also discovered that the significant effect of water-cement ratio on the fresh and hardened properties of the rubberized mortar was due to the water content in the mixture. Meanwhile, the use of NaOH as treatment to crumb rubber improved the flowability, compressive strength and flexural strength of the rubberized mortar

Energy Efficiency through Building Envelope in Malaysia and Singapore

The optimisation of fossil fuel consumption for generating electricity for building cooling is among the objectives set by most of the countries in the world. Currently, the American and European standards are among the most referred standards in the world for optimising heat transfer through the building envelope. However both standards do not reflect climate specifications of some countries such as those located in the humid tropics. The divergence in the approaches adopted by several Asian countries in minimising the heat transfer through the building envelope added another complexity to the topic. Other complexities are the divergence of European and American standards and the additional issue about the lack of validated weather data (TRY) in the humid tropics such as the case of Malaysia and Singapore. Those and other relevant issues on energy efficiency through the building envelope were addressed in the present article. Additionally a worked example and Excel sheet formulas were developed while considering Malaysian and Singaporean codes. Some recommendations were also suggested in the present article when deemed necessary

Parametric Study of Fire Performance of Concrete Filled Hollow Steel Section Columns with Circular and Square Cross-Section

Concrete filled hollow steel section column have been widely accepted by structural engineers and designers for high rise construction due to the benefits of combining steel and concrete. The advantages of concrete filled hollow steel section column include higher strength, ductility, energy absorption capacity, and good structural fire resistance. In this paper, comparison on the fire performance between circular and square concrete filled hollow steel section column is established. A threedimensional finite element package, ABAQUS, was used to develop the numerical model to study the temperature development, critical temperature, and fire resistance time of the selected composite columns. Based on the analysis and comparison of typical parameters, the effect of equal cross-sectional size for both steel and concrete, concrete types, and thickness of external protection on temperature distribution and structural fire behaviour of the columns are discussed. The result showed that concrete filled hollow steel section column with circular cross-section generally has higher fire resistance than the square section

Strength Characteristics and Temperature Distribution of Concrete Containing Crumb Rubber as Partial Replacement of Fine Aggregate

This paper presents an experimental study on the strength characteristics and temperature distribution of concrete containing crumb rubber as partial replacement of fine aggregate. This study examines the effect of different percentages (3%, 5%, 10% and 15%) of crumb rubber on concrete with strength of 25 N/mm2 and 30 N/mm2. The results show that crumb rubber reduces slump, compressive strength, and flexural strength of concrete. Moreover, concrete containing crumb rubber has higher temperatures than plain concrete when exposed to fire

Effect of Long-distance Earthquake from Philippines and Sulawesi to Sabah Region

Sabah is known for its active earthquake activities, especially in Ranau, Kudat and Lahad Datu areas. The effects of local earthquake can reach MW 6.0. Furthermore, Sabah was also hit by earthquakes from neighbouring countries such as Sulawesi and Philippines. These countries produce highly active earthquakes that can reach as high as MW 8.6. The increase in the frequency of earthquakes is one of the concerns of the Sabah government for the safety of its people because most people live in concentrated areas near the coast. This study shows the effects of major earthquakes from the Philippines and Sulawesi which have been recorded between 1900 to 2020 and analyzed in terms of peak ground acceleration (PGA). The eastern region of Sabah is adopted in the analysis for the effect of long-distance earthquakes, as these areas are close to both countries. The analysis uses standard seismic hazard assessment procedure with compilation magnitudes greater than MW 5.0. In the final analysis, it is shown that the effects of large earthquakes from both countries are relatively small compared to the effects of local earthquakes