Aspects of continuity in steel and composite frames

This thesis concerns the continuity in steel and composite frame and specifically the region of the connections. It reports on five main areas as follows: 1. Seven beam-to-beam connection tests were conducted to study the structural performance of composite end plate connections. Various parameters such as the types of connections, amount of reinforcement, beams sizes, and the degree of shear connection were investigated. The investigation confirmed a similar overall response of moment-rotation (M-φ) curves to beam-to-column tests and justified the restriction by current design codes of having partial shear connection in hogging moment region. A prediction method to estimate the initial stiffness of composite connection has also been proposed. 2. The effects of concrete encasement on structural response of end plate joints of slimfloor beams were investigated. Five specimens of beam-to-column connection of slimfloor were tested. Parameters such as end plate thickness and bolt sizes are included in the study. The results have shown that proper reinforcement and design are needed if the connections are to be considered as a composite joint. 3. Tests were carried out to improve the bond capacity of encased slimfloor. A total of six push-out tests each with different type of “shear enhancer” were performed. The load at initial slip is not greatly depend on the types of enhancer and there were indications that the resistance of the enhancer only became effective after slip, due to bond failure, had occurred. 4. As far as stability of composite beams in the negative moment region is concerned, local buckling has been identified as one of the problems. The action of reinforcement may reduce many hot-rolled section to be in Class 3. Studies were conducted on published data to explore the possibility of upgrading Class 3 to Class 1. The studies indicated that beams of Class 3 web showed the characteristics of beams with higher class if the connection was full strength. Many of the Class 3 beams used in composite beams can only be upgraded to Class 2 and not to Class 1. 5. A method applicable to the design of unbraced multi-storey frames to specified limits on horizontal sway deflection is proposed. Only simple calculation are required by the method and its application is illustrated by worked example

Ultimate shear capacity and failure of shear key connection in precast concrete construction

This paper presents the experimental results on the strength of shear key connection in precast concrete construction. The use of shear key is to connect two separate precast components to increase the shear resistivity of the joint surfaces. The proposed shear key shape in this study comprises of triangular, composite rectangular, semi - circle and trapezoidal. In addition, the trapezoidal shape is made up with 3 different key’s angles. All specimens are tested using the “push - off” method to obtain the ultimate shear capacity of which is due to the failure of the connection. From the analysis, stiffness, elastic and plastic behaviour, and the mode of failure is discussed to determine the most effective shape of the proposed shear key. From the findings, semi - circle shear key produced the highest shear capacity at 62.9 kN compared to that of the other shapes. Meanwhile, the trapezoidal shape at an angle of 45° produced the highest shear capacity at 44.1 kN. Together in the aspect of stiffness,the 45° trapezoidal shapes produced the highest resistance towards slip at 166.7 kN/mm. Failure mode are mostly due to shear, sliding and diagonal tension crack. Large slip of 7.35 mm is recorded from the triangular shape. The large slip is maybe due to sliding since the angle of the key faces to the shear plane is 45° which indicates to less interlocking compared with the other shapes they form an angle of 90° with the shear plane

Properties of hardened concrete bricks containing expanded polystyrene beads

Polystyrene aggregate concrete is one of many lightweight and low strength materials. This project reports the results of an experimental investigation into the properties of hardened concrete bricks containing expanded polystyrene beads. The beads are used as part of sand replacement in the mixes. A total of 200 samples of bricks with the standard size of 215mm x 102.5mm x 65mm were prepared in this study. Among the properties studied were compressive strength, water absorption, drying shrinkage and wet expansion of the polystyrene concrete bricks. It was found that polystyrene concrete is very prone to segregation and has low compressive strength. The properties of the bricks are mainly influenced by the content of polystyrene beads in the mix. The results indicate that polystyrene concrete mix with certain portion of the beads may provide as a suitable alternative material in the construction industry

Direct design to horizontal sway, limitation for unbraced steel frames

A meth od applicable to the design of unbraced multi-storey steel frames to specified limits on horizontal sway deflection is presented. This method of design is the extension and combination of the work by Wood and Roberts ell and Anderson and Islam [2]. Only simple calculations are required by the method and its application is illustrated by worked examples. Regular and nonregular steel frames are considered. The method proposed is suitable for the design of unbraced multi-storey frames if the choice of sections is contro lled by sway de flection

Structural performance of composite beam with trapezoid web steel section

An experimental work on a composite beam with trapezoidally corrugated web steel section has been carried out to study its structural performance. A full scale composite beam test specimen with trapezoid steel section was tested under bending moment. For comparison, a specimen of composite beam with flat web section was also tested in the same way. Deflections, position of neutral axis, distribution of strain across the depth of the composite section were measured and analysed. The results show that the composite beam with trapezoid web has no significant difference in its structural performance compared to the composite beam with normal flat web

Hybrid beam-to-column connections for precast concrete frames

The connections between precast concrete components play an important role in determining the successful of precast concrete framed structures. In particular, the connection between beam-to-column that will affect the load distribution, strength, stability and constructability of the global structure. The understanding on the behaviour of the connection is important and can only be assessed by conducting experimental tests. The main objective of this research is to investigate the moment of resistance and the behaviour of simple beam-to-column connections in precast concrete frames. The experimental test comprised a total of four specimens, which were limited to simple beam-to-column connections in precast concrete frames. The behaviour of loaddisplacement relationships, moment-rotation relationships and types of failure in connections are also investigated. Moreover, the development of safe, economical, simple and ductile precast beam-to-column connections conforming to building code requirements could be proposed

Design and performance of tubular steel scaffolding

Some structural design concepts of tubular steel scaffolding are presented herein. Factors that are considered in the design are loading condition, basic structural element, bracing, fonndation and ancillary fittings. Emphasis is given to the use of modular frame scaffoldings according to the standards in some countries. Finally, the result of system performance test on a typical modular frame scaffolding system produced locally is presented. The results shows that the frame system has high' buckling load capacity arid complies with the standard specification

Analytical study on secondary bending moment in trapezoid web beam

Trapezoid web beam is a type of steel I-section in which the web is made corrugated in a trapezoidal profile form. The corrugated thin web is continuously welded to the flanges along the top and bottom edges. Trapezoid web beam is a built up section that able to support vertical loads over long spans. The higher bending capacity is achieved by increasing the depth of the section. Increasing the depth will increase the slenderness of web and hence reducing the shear buckling capacity. Ordinarily, the economic design of steel web I-beam requires thin web. To avoid shear buckling, intermediate stiffener has to be used, or alternatively, the web can be made corrugated in trapezoidal profile. When beams with corrugated webs are compared with those with stiffened flat webs, it can be found that trapezoidal corrugation in the web enables the use of thinner webs and trapezoidal web beams eliminate costly web stiffener

102 - str - mus stiffening of cold - formed steel section at plastic hinge formation

This study is carried out to investigate the method that can be used to stiffen the cold-formed steel section so that the section becomes a plastic section and thus can be used for plastic design of portal frame. In this study, experimental works have been done to study the formation of plastic hinge of cold-formed sections of various slenderness ratios. In the first series of tests, 2 numbers of lipped channel steel sections with the size of 75 x 30 mm and 0.65 mm thickness had been tested. The beams were simply supported at each ends. In the second series, rectangular sections were built-up each from two 75 X 30 mm single channel sections connected fece to face, to have different slenderness ratio of their elements. From the test, it was found that the formula used for the determination of design bending moment provided in the BS 5950 has not been proved reasonably comparable with that of experimental results. Two point bending method was used in the test. At high deflection, warping of the compression flange was determined. The failure was in the mode of local flange buckling, followed by budding of the web. The stiffener made of splice plates were used to stiffen the section and thus transforming the section into plastic section at the plastic hinge location. Two sections were combined and jointed together face to face to make it into a single section. From the study, it is concluded that stiffening of cold-formed steel section by the use of splice plate stiffeners needs to be improved to form plastic hing

Field capacity of steel pile with corrugated web surface

A series of loading test on steel piles with web of different corrugation profiles has been carried out to study the performance of piles with trapezoid web in resisting loadings. Hypothetically, the inclined part of the corrugated web can provide an extra skin friction capacity of the pile. In the full scale tests, maintained load and constant rate of penetration tests were carried out. Six piles of different web corrugations were used in the test, all of which had the dimension of 200 x 80 mm and 5.0 m length. Maintained load test and constant rate penetration test on all the pile types had been carried out. The force versus settlement was plotted, designated as the resistance behaviour of the steel pile section against the vertical load. Comparison had been made to present the differences of the skin friction resistance capacities between both types of piles. The pattern of the settlement and end bearing capacity of the pile were also analyzed. The test results indicate that the total bearing capacities of pile with trapezoid web are higher than that of the flat web section of the same cross section area. The bearing capacities of piles with full corrugations are in the range of30 kN while the piles with flat web are only 20 kN. The study shown the trapezoid-section pile can be used as a better alternative to the conventional-section pile in term of the load bearing capacity