Performance of palm oil clinker as a bio-filler with hybrid fillers in intumescent fire protective coatings for steel

Intumescent coatings are an effective method for fire protection of steel structures. The search for more environmental friendly intumescent coatings has led to the utilization of palm oil clinker (POC) as a bio-filler in solvent-borne intumescent coatings in order to improve fire protection performance, mechanical strength and water resistance of steel structures. In this research, POC and hybrid fillers are mixed with an acrylic binder and then blended with flame-retardant additives in order to produce intumescent coatings. The samples were tested using Bunsen burner test, thermogravimetry analysis, surface spread of flame test, field emission scanning electron microscopy, static immersion test, and adhesion strength test. It was found that the optimum composition of POC and hybrid fillers gives the best fire protection performance with the lowest equilibrium temperature (171.3°C), high thermal stability, good water resistance and excellent mechanical properties. The results of the surface spread of flame test show that Sample A3, A4, and A6 were classified as Class 1, which is the best classification. For Sample A6 (a hybrid formulation), the addition of aluminium hydroxide gives better water resistance with the lowest rate of weight change (<0.2%), while the addition of magnesium hydroxide enhances the bonding strength of the coating up to 125% compared with Sample A1 which only has a single filler POC. It can be concluded that the optimum composition of POC and hybrid fillers results in intumescent coating with the greatest fire protection performance

Eccentricity Optimization of NGB System by using Multi-Objective Genetic Algorithm

In this study, a new method for designing a particular braced system by using multi-objective genetic algorithm is proposed. This type of braced system, which is called non-geometric braced system are mostly used in seismic areas and it allows architects to have more openings in the panels. Non-straight diagonal member of this system introduces eccentricity and it is connected to the corner of the frame by a third member. In designing this system, designers often use trial and error method to locate the connection point of the brace elements by considering various parameters which affect the design such as opening and frame dimensions, cross section areas of brace elements and the location of brace element connection. Hence, finding the best connection point with maximum stiffness and minimum weight of brace elements with conventional methods is not trivial. In this study, a multi-object genetic algorithm is proposed in determining the best selection for connection point and also the brace elements' cross section area proportions which is the key rule in determining the stiffness of the system. Boundary equations are set by introducing feasible area to avoid improper individuals followed by utilization of some operators such as selection, mutation, crossover and elite genetic algorithm. Based on the plain aggregate approaches for transforming the objective vector in scalar, some modifications are proposed to assist designers in making decision on prioritizing between the frame stiffness and brace frame weight in their design

Behaviour and design of beam-to-column connections under fire conditions

In this paper, the main approaches used for developing a component-based connection model are presented and discussed. The model is capable of simulating the behaviour of typical connection configurations in both steel and composite framed structures under monotonic and cyclic loading conditions at ambient as well as elevated temperatures. Validation of the proposed connection model is carried out by comparison against a range of available experimental results, and implementation is undertaken within an advanced finite element program that accounts for material and geometric non-linearities. A series of sensitivity studies are then presented in order to demonstrate the scope of application of the proposed model, and to examine the influence of connection behaviour on the overall structural performance in fire. A number of structural configurations are investigated starting from isolated members and reaching more detailed representations. Several factors are assessed including connection type, boundary conditions and temperature effects. Finally, key parameters and considerations related to connection design are examined

Cyclic performance of stiffened steel plate shear walls with various configurations of stiffeners

In this study, experiments were conducted on five specimens of stiffened and unstiffened steel plate shear walls under cyclic loading. First, the specimens and frame design, material properties, and test setup were described. The behaviors of the unstiffened aluminum and steel infill plates were compared with three configurations of stiffened steel plate, i.e., cross-stiffened, circular-stiffened, and diagonally stiffened. The cross-sectional areas of the stiffeners were the same for all stiffened specimens. The results showed that the aluminum infill plate exhibited less ductility. By contrast, the unstiffened steel plate was very ductile, exhibiting a stable hysteresis curve and no tearing. The energy-absorption capacity of the steel plate shear walls increased for all stiffening configurations. Among all configurations, the cross-shaped stiffeners showed considerable increase in shear stiffness, ductility, and energy-dissipation capacity. The plate frame interaction method could predict the ultimate shear strengths of the unstiffened and cross-stiffened panels with good precision. The circular-stiffened steel shear wall seems to behave more desirably in high-amplitude displacements

Bolted connections to tubular columns at ambient and elevated temperatures: A review

Tubular column members have been widely adopted in current construction due to its numerous advantages. However, the closed-section profile characteristics of tubular columns severely limit the connection possibilities. Welding type is acceptable but discouraged because of on-site issues. Blind-bolted connection is preferable because of its simplicity, economic benefit, and easy assembly. This paper presents a state-of-the-art review on bolted connections to tubular columns for bare steel tubes, including square and circular sections. Available studies on bolted connections at ambient and elevated temperatures are reviewed, but emphasis is given on the latter. Various methods of determining the connection performance through experimental, analytical, component based, and finite element approaches are examined. Future research areas are also identified

Seismic performance of a new through rib stiffener beam connection to concrete-filled steel tubular columns: An experimental study

This paper proposes a new moment-resisting connection known as a through rib stiffener beam connection, which is directly passed through a pre-slotted circular column with concrete infill. Four half-scale cruciform specimens with orthogonal beams were tested under cyclic loading. The failure modes, hysteretic performance, rotation capacity, strength and stiffness degradation, ductility, and energy dissipation of the connections were analysed. The effect of different parameters, such as through rib stiffener and beam section size, on the connection performance was investigated. The experimental results indicated that the new through rib stiffener beam connected with circular columns exhibited a large hysteretic enclosed area, good ductility, and excellent energy dissipation. The results proved that the proposed connection satisfies the seismic provisions and ductility design requirements for it to be utilized as moment-resisting frames in a seismically active area

FE modelling of the flexural behaviour of square and rectangular steel tubes filled with normal and high strength concrete

In this research, numerical investigations were carried out to study the behaviour of concrete filled steel tubes having square or rectangular cross-sections. Separate models were used for both normal strength concrete and high strength concrete. More than 50 experimental results were used to verify the FE model and it was found that the FE model accurately predicts the load-deflection curve and ultimate moment capacity of the Concrete filled steel tube (CFST) beams. Thereafter, a parametric study was carried out to evaluate the effect of depth-to-thickness ratio (20−200), compressive strength of infilled concrete (2–100 MPa), shear span-to-depth ratio (1–8), depth-to-width ratio (0.6–2), and yield strength of steel tube (380–490 MPa) on the flexural behaviour of square and rectangular CFST members. It was found that the depth-to-thickness ratio, yield strength of steel and height-to-width ratio has significant effect on the ultimate capacity of CFST beams. The effect of shear span-to-depth ratio and strength of infilled concrete was found to be marginal. Finally, the results of parametric study and experimental data available in literature were used to check the accuracy of the existing design methods presented in EC4 (2004), CIDECT, AISC (2010) and GB50936 (2014). From comparison, it was found that GB50936 (2014) was more accurate but unsafe for low strength infilled concrete. For all cases, EC 4 (2004) was found to be safe and hence is recommended