Theoretical and experimental analysis of load-carrying capacity of steel-concrete composite beams with glass-fibre-concrete slab
The paper deals with the problems of the theoretical and experimental investigation of load-carrying capacity of steel-concrete composite beams with glass-fibre-concrete (GFC) slab. The paper presents some selected results of the more extensive research realized on the authors workplace and oriented to the utilization of high-strength steels and high-performance concretes in steel-concrete composite structural members. This paper is directed towards one part of this research only, which represents theoretical analysis of the bending moment capacity and experimental verification of the actual bending moment capacity of steel-concrete composite beams with glass-fibre-concrete (GFC) slab in connection with their actual behaviour and corresponding relevant failure mechanism. Within the framework of the bending moment capacity analysis four basic types of beams have been (or will be, respectively) investigated, all of them composed of 3 different steel IPE cross-sections (IPE180, IPE200, IPE220) and concrete slab: (i) beams with GFC slab without usual steel reinforcement subjected to sagging bending moment, to investigate the contribution of GFC only to the sagging moment capacity; (ii) beams with GFC slab with steel reinforcement (reduced amount) subjected to sagging bending moment, to investigate the contribution of GFC slab and steel reinforcement together to the sagging moment capacity and to compare it with the first case; (iii) beams with plain concrete (PC) slab subjected to the sagging bending moment, to compare the results with the first case only; (iv) beams with GFC slab without steel reinforcement subjected to hogging bending moment, to verify the contribution of GFC to the hogging moment capacity. During the experimental parts of this research in common 27 loading tests of steel-concrete composite beams have been realized so far (but no all results are evaluated in detail so far) and other 9 specimens will be tested immediately. The attention was paid mainly to the following significant problems: the efficiency of the utilization of fibre-concrete slab in steel-concrete composite beams subjected to sagging or hogging bending moments, too; the effectiveness of the contribution of glass-fibre-concrete to the moment capacity of steel-concrete composite beams in comparison with reinforced concrete and plain concrete. Key-Words: Composite member, steel-concrete beam, glass-fibre-concrete, load-carrying capacity, resistance, sagging bending moment, experimental verification, theoretical analysis.
Methods based on the approaches of the design assisted by testing applied for the determination of material properties
The paper is focused on the application of the methods based on the approach of the design assisted by testing for the determination of material properties of fibre-reinforced cement-based composites used mainly for the building facade claddings, but also as a part of load-carrying structures for the slabs of steel-concrete composite beams, for example. In the recent period new advanced non-traditional building materials exist and have been developed, but their physical-mechanical properties, namely characteristic and design values and partial safety factor are not generally known. The application of the philosophy of the design assisted by testing is one of the possible ways, how effectively and reliably to determine characteristic and design values of material properties. The methods of the design assisted by testing are based on experimental results evaluation arising from the statistical and probabilistic approaches. The procedures for the determination of characteristic and design value of the material property implemented in standard rules are usable not only for usual cases of the large test number, but also for small or very small test number, where the test number, type of the property distribution and its statistical characteristics shall be considered.
Shape Stabilization of Steel Suspension Bridge
Stabilization of primary shape of suspension bridges is one of the governing design problems of the structure. The form (i.e., shape changes of suspension steel bridge) is prescribed more by kinematic vs. elastic displacements. Kinematic displacements developed due to asymmetric loadings. Total displacements can be relatively split into kinematic and elastic components. Kinematic displacements are first determined, and then elastic displacements are evaluated considering the shape of cable to be changed. Such a relative splitting of displacements allows evaluation of the contribution of both total displacement components and use of the efficient engineering stabilization tools. The developed analytical expressions for determining total and kinematic displacements for cable any cross are given. The suspension bridge primary shape stabilization methods and their efficiency are analyzed. It is proposed to introduce the engineering tools for constraining horizontal displacements of suspension cable, resulting in reduction of vertical cable displacements, and also in stabilizing of the primary shape of the bridge.