Standardisation of partial strength connections of extended end-plate connections for trapezoid web profiled steel sections

Traditionally, connections are usually classified as pinned or rigid although the actual behaviour is known to fall between these two extreme cases. The use of partial strength or semi-rigid connections has been encouraged by codes and studies on the matter known as semi-continuous construction have proven that substantial savings in steel weight of the overall construction. The objective of this paper is to develop a series of standardised partial strength connections tables of extended end-plate connections for trapezoidal web profiled steel (TWP) sections. The range of standard connections presented in tabulated form is limited to eight tables comprised of different geometrical aspects of the connections. These tables could enhance the design of semi-continuous construction of multi-storey braced steel frames. The connections are presented in the form of standardised tables which include moment capacity and shear capacity after considering all possible failure modes. A method proposed by Steel Construction Institute (SCI) which take into account the requirements in Eurocode 3 and BS 5950:2000 Part 1 were adopted to predict the moment capacity and shear capacity in developing the tables. A series of tests have been carried out to validate the results of the standardised tables. The test results showed good agreement between theoretical and experimental values. It can be concluded that the proposed standardised tables for TWP sections is suitable to be used in the design of semi-continuous construction

Structural and economic aspects of the use of semi-rigid joints in steel frames

This thesis reports on five main areas as follows: 1. Braced steel frames designed for semi-continuous construction were studied to determine savings in both cost and weight. Various frame parameters such as the number of bays, use of grade S355 steel, beam spans, types of connection, and selection of beam size were investigated. The investigation confirmed that semicontinuous construction contributes to worthwhile percentage savings on both cost and weight. 2. Analysis and design of steel unbraced frames bending on both axes were performed with emphasis on stability and deflection checks. Rules are proposed to improve the stability and stiffness. For connections to the minor axis, a proposed joint detail is presented. The performance of the frames was checked for collapse load level at ULS; deflection limits at SLS were also checked; in both cases using first and second order analysis. The investigation demonstrated that the frames should be restricted to less than four storeys. 3. A study on minor axis joints was carried out for flush end plate connections connected to the column web. Previous experimental results of moment and stiffness were compared with predicted values. Moment values were predicted using Gomes' formulae. The stiffness due to the column web was predicted using finite element analysis. The results showed good agreement between experimental and predicted values. The study on the connections was extended to their suitability in steel frames bending about the minor axis; the investigation confirmed that the connections were not suitable for unbraced wind-moment frames. An equation for prediction of initial stiffness was nevertheless established for the connection. 4. Steel frames with composite beams designed for minimum wind combined with maximum gravity load were studied for their performance, taking into account cracking along the beams. The investigation showed that the frames meet the requirements of deflection and sustain a load level of 1.0 for ULS. For frames studied for maximum wind combined with minimum gravity load, the moment capacity of the joints governed the design which resulted in a deeper beam section. 5. Seven tests were carried out for a new type of shear connector system installed by compressed air. The aim of the tests was to study the shear capacity and ductility of the studs. The tests showed that the pins fail due to fracture and the stud systems needs some improvements to increase the key structural properties

Engineering properties of bio-inspired cement mortar containing seashell powder

Cement mortar is a semi liquid formed by a composite of cement, sand and water. Generally, cement mortar is used as a medium for bricks laying in construction. Nowadays, the properties of various types of waste materials are studied as construction material in buildings such as blast furnace ash, fly ash and palm oil fuel ash. In this study, the seashell is used as a replacement of building material in cement mortar.Seashell consists of high amount of calcium carbonate that provides remarkable mechanical properties and suitable to be used as building material. The engineering properties of cement mortar is studied, which including the compressive strength, flexural strength, splitting tensile strength, durability, modulus of elasticity in compression, setting time, water absorption and shrinkage. Cockle (Anadaragranosa) and mussel (Pernaviridis) are selected to replace the sand in the cement mortar with a ratio of 0, 25, 50, 75, and 100 percent by total weight of sand. A total number of 2800samples are prepared and tested up to 1 year and subjected to four exposure conditions, which are water, air, natural weather and wet-dry cycle.The replacement of seashell in cement mortar is likely to increase its engineering properties especially compressive strength due to high amount of calcium carbonate.The replacement of seashell in cement mortar will reduce the construction cost, improve the engineering properties of mortar and can be applied in various mortar applications

Strength capacity of bolted shear connectors with cold-formed steel section integrated as composite beam in self-compacting concrete

The use of composite systems comprising of concrete and hot-rolled steel (HRS) sections is well established as observed by extensive rules and requirements for their design as prescribed in current design codes. There is, however, few technical information available about the use of composite systems that incorporates the use of light gauge steel sections, despite the potentials of the system in residential and light industrial constructions. Therefore, this study investigates the strength capacity of bolted shear connectors with cold-formed steel (CFS) section integrated as composite beam in self-compacting concrete. In this paper, four composite beam specimens of dimensions (4500 mm x 1500 mm x 75 mm) with bolted shear connectors of M12 and M14 of grade 8.8 installed on the upper flanges of the coupled back-to-back CFS I-section with longitudinal spacing’s of 250 mm and 300 mm centers and spaced 75 mm laterally were fabricated, cast and tested to failure using four-point bending test. Shear connector size and the longitudinal spacing were the varied parameters, and their influence was investigated on the ultimate load and ultimate moment capacities. The results showed that, the ultimate load and ultimate moment capacities were both influenced remarkably by the studied parameters. However, results of theoretical analysis, revealed good agreement between the experimental and the theoretical results. This shows that, the plastic analysis results for the ultimate moment capacity of the composite beams can be estimated efficiently by using the constitutive laws as prescribed by Eurocodes

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

Experimental investigation of end-plate connection with cruciform column section

This paper presents an experimental investigation on typical end-plate connection with reduced beam-to-end plate welding, connected to cruciform column (CCUB) section. The study aims to reduce the cost of fabrication and materials. Two tests were conducted to study the behavior of the proposed connections and evaluate the failure modes, moment resistance, initial stiffness and rotational capacity of the connections. The experimental results indicated that the failure mechanisms for the tested specimens begin with the end-plate yielding followed by bolt slippage that was limited to the tension region of the joint due to the tension forces exerted through the top bolt rows. The experimental results will then be used to validate the theoretical model for the T-stub idealization of the tension zone

Strengthening method and structural performance of cold-formed cut-curved steel under compression

Cold-formed steel section (CFSS) is a popular material in the steel structure that has been recognised in construction work. CFSS with curved section is a new section that proposed in the CFSS and still being studied by researchers. Steel curved section, whether by using hot-rolled or cold-formed steel become essential and significant in the design that be suited by the architectural demand. For this reason, the CFSS is recommended to provide the curve in the structure and dispute the use of the hot-rolled steel. In the study, the CFSS is curved by using a clamp, small bender and welding machine. Through this process, CFSS with cut-curved (CFSS-C) is strengthened by welding in particular location at flange and web. The CFSS-C are established into five specimens with different of welding location and added with one normal specimen (CFSS-N) as a control specimen. The CFSS is tested for the structural performance of the column specimens with the height, 1000 mm under compression load and lastly the suitable strengthens method with highest of ultimate load is selected. From the testing, CFSS-C4 is reported to decrease about 32.26 % when compared with normal specimen

Comparative study of eight metallic yielding dampers

The seismic resistance of structures can be enhanced by using passive energy dissipation devices in order to dissipate earthquake energy. One of these devices is metallic yielding dampers which is low-cost, but highly-efficient. This paper aims to compare four key variables among eight metallic yielding dampers. Theses four parameters are equivalent viscose damping ratio, large load to weight, ductility and cumulative displacement. The dampers were selected based on the availability of the experimental data in the literature. As the first step of the methodology eight particular dampers with its load-displacement curve were carefully chosen to study. Three dissimilar last loops of force-displacement hysteresis were selected and drawn for each damper. Then the above mentioned parameters were calculated and compared to get results and draw conclusion. The outcomes reveal the relationship of the four studied parameters with each other. The results show there is a relationship between the mechanisms of energy dissipation with the specific range of equivalent viscous damping ratio in the studied metallic dampers

Time-dependent physicochemical characteristics of Malaysian residual soil stabilized with magnesium chloride solution

The effects of non-traditional additives on the geotechnical properties of tropical soils have been the subject of investigation in recent years. This study investigates the strength development and micro-structural characteristics of tropical residual soil stabilized with magnesium chloride (MgCl2) solution. Unconfined compression strength (UCS) and standard direct shear tests were used to assess the strength and shear properties of the stabilized soil. In addition, the micro-structural characteristics of untreated and stabilized soil were discussed using various spectroscopic and microscopic techniques such as X-ray diffractometry (XRD), energy-dispersive X-ray spectrometry (EDAX), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR) and Brunauer, Emmett and Teller (BET) surface area analysis. From the engineering point of view, the results indicated that the strength of MgCl2-stabilized soil improved noticeably. The degree of improvement was approximately two times stronger than natural soil after a 7-day curing period. The results also concluded the use of 5 % of MgCl2 by dry weight of soil as the optimum amount for stabilization of the selected soil. In addition, the micro-structural study revealed that the stabilization process modified the porous network of the soil. The pores of the soils had been filled by the newly formed crystalline compounds known as magnesium aluminate hydrate (M-A-H).Ministry of Education Malaysia under the Fundamental Research Grant (FRGS) (R.J130000.7822.4F658); Universiti Teknologi Malaysia (UTM); Construction Research Centre UT

Splitting Tensile Strength of Lightweight Foamed Concrete with Polypropylene Fiber

This paper presents the design mix of foamed concrete and split tensile strength of lightweight foamed concrete with the addition of polypropylene fiber. The design mix of the foamed concrete was targeted to achieve a density of 1500 kg/m3. Six different water-cement ratios (w/c) range from 0.30 to 0.40 were taken into consideration. Three different group of LFC with 0% PP, 0.25% PP and 0.40% PP are prepared. The optimum w/c was determined by comparing the compressive test result of different percentage polypropylene fiber. By using the LFC with optimum w/c ratio and designated amount of PP of 3:1 c/s ratios, the concrete specimens were tested with splitting tensile test to determine the effects of PP to the tensile strength of the lightweight foamed concrete. From the result, it is found that by using 2:1 c/s ratio, the optimum w/c of mix with 0% PP, 0.25% PP and 0.40% PP are 0.36, 0.34 and 0.32 respectively, while for c/s equals to 3:1, the optimum w/c are 0.34, 0.32 and 0.32 respectively. From the splitting tensile result, under a controlled density of 1500 ± 50 kg/m3, the tensile strength range of 0.991-2.138 MPa were observed. From the result, it can be concluded that, the addition of polypropylene fiber to the lightweight foamed concrete does affect the tensile strength of the foamed concrete. However further addition of PP will not cause any positive and significant effect to the tensile strength of lightweight foamed concrete