Asian journal of civil engineering
Volume:7 Issue: 1, February 2006

The paper presents a study on the fatigue strength of Steel Fibre Reinforced Concrete(SFRC) containing fibres of mixed aspect ratio. To obtain the fatigue lives of SFRC atvarious stress levels, beam specimens of size 500 mm x 100 mm x 100 mm were testedunder four-point flexural fatigue loading. Static flexural tests were also carried out todetermine the static flexural strength of SFRC prior to fatigue testing. The specimensincorporated 1.0% volume fraction of corrugated mixed steel fibres of size 0.6 x 2.0 x 25mm and 0.6 x 2.0 x 50 mm in different proportions. All the fatigue tests were conducted on MTS servo-controlled test system where as all the static tests were conducted on a similar INSTRON machine. Fatigue life data obtained has been analysed in an attempt to determine the relationship among stress level S, number of cycles to failure N and probability of failure Pf for SFRC. It was found that this relationship can be represented reasonably well graphically by a family of S-N-Pf curves. The experimental coefficients of the fatigue equation have been obtained from the fatigue test data to represent the S-N-Pf relationships analytically.

Seismic resisting structures are expected to maintain adequate stiffness during frequent but moderate excitations on one hand, and to dissipate a large amount of energy under damaging earthquakes on the other hand. In this paper, a relatively new seismic resisting structural system, which satisfies stiffness and energy dissipation requirements simultaneously, is numerically investigated using nonlinear finite element analysis procedure. In this system, earthquake energy is dissipated through large inelastic deformation occurred within a shear panel. The shear panel acts as a ductile link beam connecting braces to the floor beam. This paper aims to find out key issues influencing cyclic behaviour of frames braced by Shear Panel System (SPS), like Cross-sectional properties of SPS and link length. The results indicate that shear panel length significantly affects cyclic performance of this system. Use of shorter links results in more stiffness and at the same time more stable hysteretic behaviour and energy dissipation capacity. Finally, the paper presents a mathematical model to evaluate lateral stiffness of braced frames braced having SPS.

The aggregates (sand and gravel) form the skeleton of the concrete, they occupyapproximately 75% of its volume, and intervene directly on the physical and mechanicalproperties of concrete. The aim objective of this experimental work consists in:- Substituting sand by granulated blast furnace slag.- Substituting natural gravels by crystallized slag.The use of the method of substitution permits to improve the strength of the concrete, to increase the production of building materials in Algeria and to protect the environment, it also gave an economic approach to the construction industry.The experimental results obtained show that the partial substitution of ordinary sand byslag gives better results compared with the ordinary concrete, the total substitution of natural gravels by crystallized slag improves the strength, but the full replacement of fine and coarse aggregates by slag products affect negatively the strength of concrete.

The applicability of graph theory for optimizing the sparsity and the bandwidth of cycleadjacency matrices of graphs is shown. Fundamental and subminimal cycle basis selectionalgorithms are presented in an algorithmic way. It is shown how the pattern of the cycleadjacency matrix changes during different phases of cycle selection and in particular whencycles are ordered. At each stage small pieces of code are presented to illustrate thesimplicity of the implementation of the graph theoretical approaches using a computerlanguage such as C++. The use of other languages should not cause much difficulty,although many aspects of an object oriented language such as C++ have been employedextensively throughout. This is intended to demonstrate the efficiency of graph theoretical methods combined with advanced techniques of computer programming

The assessment of piles lateral friction involves the determination of the interface shearingresistance at large displacement. Consequently, the shearing resistance mobilised at largedisplacements, at the interface between cohesive soils and steel and concrete of varyingroughness has been studied in the ring shear apparatus. The latter is known to offer the best mean of studying shearing resistance when soils undergo large displacements. The focus of this work is to highlight the solid material surface roughness effect. Results obtained from soil-soil and soil-interface shearing tests are presented. They indicate that the surface roughness and the average diameter of particles, which are combined into the influence of relative roughness R, have a significant effect on the interfacial shear strength at a given normal stress level. With respect to R, three shearing modes are likely to take place: shearing at the interface, shearing within the soil and an intermediate mode involving these two types of shearing. For the second mode, the shear strength at the interface soil-rough solid materials (steel and concrete) is likely to be greater than the shear strength of the soil, particularly for soils whose major mineral component is montmorillonite.

Focusing on out of plane buckling of three member y-shaped concentric steel bracings, 5 full scale one story one bay specimens have been tested in BHRC Structural Engineering Lab. The results show that inelastic buckling is the governing mode of failure. The buckling load of bracing increases by moving the convergence point towards the center of bay, while the story drift at buckling decreases by this geometrical change. Hysteretic energy absorption and damping of bracing increases by moving the convergence point towards the corner of frame. By reinforcing the bracing members and increasing the radius of gyration of brace sections, the hysteretic energy absorption and damping of bracing has been slightly increased.

This paper presents analysis of tall building under wind load excitation taking account ofpulsation. The path of the analysis using MatLAB, Lira and Russian national code SNiP arepresented. Use of wind velocity-time graph is employed where the change in wind pressure (pulsation) with time is assumed to be proportional to a similar change in wind velocity. Results are compared and show a conformation to dynamic behaviour of the buildings under such excitations as pulsation, thus making the analysis adequate for assessing the dynamic behaviour of a structure.

Iran Strong Motion Network started its activities since 1973, and has recorded more than5500 accelerograms up to September 2005, through which the maximum groundacceleration of about 1g is recorded due to Zanjiran [1994] and Bam [2003] earthquakes at Zanjiran and Bam stations respectively. At present the network consists of 1049 digital and 61 analogue accelerographs. In the first half of the year 2004, 363 accelerograms are recorded by ISMN and the maximum PGA of about 0.922g is occurred in Hassan Kief station in Kojur-Firouzabad earthquake of May 28, 2004.