‐ 19 - of pressure; 2) the connectors were then spun with a fast speed and thus produced friction heat at the conjunction; 3) the connectors were welded to the steel face plates by the generated heat. The Bi-steelsteel frame without in-filled concrete had certain stiffness. Therefore, this type of structure could be erected and then grouted or grouted then erected that offered flexible construction consequences. Bi-steel structure could provide high impact and blast resistances. The straight bar connectors that were directly welded to external surface plates could provide high tensile capactiy and finally resulted in high shear resistance of the section. The static behaviors of the Bi-steel structure were studied by Xie et al. (2007). The development of the Bi-steel structure was summarized by Xie and Chapman (2006). The shear strength and tensile strength under static and fatigue loads of single connector were studied to provide basic design foundation (Xie and Chapman, 2004). Structural behaviors of Bi-steelbeams subjected to static and fatigue loads were studied by Xie et al. (2007) and Foundoukos (2005). Moreover, the analytical model and finite element (FE) models were also developed to predict the strength of the Bi-steelbeams (Xie et al., 2004; Foundoukos and Chapman, 2008). A design guideline on Bi-steel structures was published by the British Steel Ltd (1999), which offered means to the applications. The Bi-steel had a wide range of applications both in civil and offshore structures. Though Bi-steel structure shows a high strength and excellent structural performances under different loading conditions, the thickness of this structure is limited within a range of 0.2~0.7 m and there are also other limitations on the dimensions of this type of structure due to the limitations of the friction welding equipments.
Fibres are utilised in order to enhance the properties of an inherently brittle and crack-prone cement-based matrix. Para- metric studies on SFRC beams under monotonic loading were carried out by means of NLFEA. The latter were initially calibrated and verified against existing experimental data of Campione et al. (2006). The investigation is focused on simply supported beams, which were designed with reduced shear reinforcement in order to incorporate a shear mode of failure. The spacing between shear stirrups was increased (with the extreme case of beams without transverse stirrups being consid- ered as well), while fibres were added to examine their potential as a substitute for the loss in conventional shear reinforcement. Based on the findings of the present investigation, it can be concluded that the addition of steel fibres consistently enhances the load-carrying capacity. The strength increase was by up to ,15% compared to the control beam specimen (i.e. the one with no increase in stirrups spacing and no fibres). Furthermore, fibres were found to increase stiffness, leading to reduced deflections. This shows that there are clear benefits of adding fibres at both the serviceability and ultimate limit states, which are important design considerations. The addition of steel fibres also led to a reduction in crack formation and propagation. It has also
El-Zohairy and Salim (2017) implemented a parametric study for post-tensioned compositebeams with external tendons. The results demonstrated that, at the same tendon eccentricity, the trapezoidal profile shows better behaviour for the strength- ened beams. However, more ductility is obtained when using the straight tendon profile. Chandramohanmouli and Kumar (2017) carried out a non-linear finite-element analysis to inves- tigate the behaviour up to failure of simply supported com- posite steel–concretebeams with external prestressing. The analytical tests carried out for the different cases studied indi- cated that the load–deflection behaviour and the ultimate loads were in good agreement with the published experimental results. Ibrahim et al. (2012) investigated the effect of several important parameters on the behaviour of external prestressed compositesteel–concretebeams by conducting a parametric study. The finite-element results for simply supported beams with full shear interactions showed stiffer behaviour compared to beams with partial shear interactions. Liban and Tays¸i (2017) examined the behaviour up to failure of cantilever compositesteel–concretebeams which were prestressed exter- nally. The authors concluded that adding prestressed tendons to compositebeams significantly increased the yield load and the ultimate load. They concluded also that the farther the tendons are located from the neutral axis, the greater is the increase in strength. Ibrahim and Salman (2015) investigated analytical continuous compositesteel–concrete beam with external prestressing by conducting a parametric study. It was found that, as the compressive strength of the concrete and the effective prestressing stress increased, the ultimate load capacity increased.
resist loads applied laterally to beam's axis. Its mode of deflection is by bending. The checkered steel-encased concretecomposite (CSCC) beam generally consists of a rolled U-shaped or C-shaped steel beam. To strengthen bonding effect and enhance slipping resistance, a CSCC beam is introduced. To investigate the real bending of the new-type of composite beam, static load tests on simply-supported CSCC beams were conducted. Trapezoidal CSCC beam can carry more load than rectangular CSCC beam according to geometry. Yield strength of CFRP (carbon fibre reinforced polymer) is much higher than checkered steel, so CFRP encased concretecomposite beam can carry more load than CSCC beam. All numerical simulations were performed using the finite element software Ansys 16.1. The load-deformation responses were analyzed using Universal testing machine (UTM).
During all experiments, the visible cracks were marked at each load increment, and the different crack patterns were observed . Figures 5.33 and 5.34 show the crack patterns and the corresponding loads in kips for all the NWC and LWAC beams respectively. In general, the cracks developed in the pure moment zone were vertical and perpendicular to maximum tensile stress. Outside the constant moment region, the cracks propagated vertically and gradually curved afterwards due to increasing the load which had caused an increase in the shear stress. Furthermore; it can be noted that, the distribution of those cracks were almost symmetrical around the center of the beam. Smaller spacing between cracks was observed in all beams with fibres. Moreover, the trajectories of the beams containing less amount of flexural reinforcement appeared straighter than the others with higher longitudinal reinforcement ratio. The influence of the fibres on the shape of the crack pattern was not evident. On the other hand, the steel fibres had a clear iMPact on reducing the crack widths and increasing number of cracks for all beams. Moreover, the effect of steel fibres extended to slightly control the depth of cracks; where beams with no steel fibres presented a longer crack depth. Crack depth and the number of cracks at ultimate load within the constant moment zone are presented in the Table 5.6. The crack spacing is discussed in section 5.6.4 of this chapter.
Abstract: Modelling and Analysis was carried out using Finite Element to study the behaviour of compositebeams according to Euro code 4 with respect to bending, shear and deflection under varying loads, and the ultimate loadings and section capacities corresponding to failure modes was evaluated. In bending the section capacity was found to increase with an increase in both concrete and steelstrength however increase in flexural resistance with increase in compressive strength is very small that is 3.2% 3.1% and 3.0% when the concretestrength was increase from 25 N/mm 2 to 30, 35 and 40 N/mm 2 respectively, compare to the way it increase with increase in the steelstrength by 27% and 21% when the strength was increase from 275 to 355 and 460N/mm 2 respectively, but the ultimate flexural load capacity of the beams decreases with increase in the beam span for both the three steelstrength. However, shear capacity of the sections remain unchanged at constant steelstrength and varying length, but increases with increase in ultimate yield strength of the steel sections by 29%, and 67% when the ultimate yield strength was increase from 275 N/mm 2 to 355 N/mm 2 and 460 N/mm 2 respectively, while allowable deflection increases with an increase in the beams span and the ultimate loadings with respect to deflection also decrease with increase in the beams span.
Fibre Reinforced Polymer (FRP) composites enjoy an array of applications ranging from aerospace, military and automotive to marine, recreational and civil industry due to their outstanding properties such as high strength to weight ratio, corrosion resistance, good thermal performance and reduction of carbon dioxide emissions both through its method of production and their effective thermal insulation qualities. FRP composites are increasingly being considered as a substitute and enhancement for infrastructure systems that are constructed of traditional civil engineering materials such as concrete and steel. Some disadvantages of FRP materials include brittleness and vulnerability to damage by ultraviolet light from exposure to sunlight, affecting their outdoor applications (Jain & Lee 2012). Although the relatively high production and material costs are considered as major drawbacks preventing FRP composites to be fully embraced for structural applications, when the cost of the structures is considered over its entire life cycle, the improved durability qualities of FRP material can make them the most cost-effective material in many instances (Gand et al. 2013).
Metal air sandwich panels or cellular metal panels are commonly used in lightweight construction. This composite panel system is made using a structured metal core sandwiched between two metal plates that give high stiffness with a minimum use of material (Fig. 1b). Guruprasad and Mukherjee  carried out an experimental and numerical analysis on the behaviour of layered steelsandwich panel subjected to blast loading and found that the impulse transfer was reduced substantially at the base of the cladding. The imparted energy was absorbed through core steel plastic deformation. The results suggest that such steelsandwich panels may be very efficient in dissipating blasts. In accordance with their findings, the study by  also concluded that the well-designed sandwich plates can sustain significantly larger blast impulses compared to solid plates of the same weight.
After the curing period of 28 days, beam specimens were kept for 24 hours in a dry state and then they were cleaned to remove grit and dirt. Then the beam specimens were whitewashed to facilitate easy detection of cracks. The beam specimens were tested in a reaction frame of 1000 kN capacity and hydraulic jack of 500 kN capacity subjected to two point loading. The beams having a span to depth ratio of 6 and shear-span to depth ratio of 2.5 were tested at the load increment of 4kN and beams having a span to depth ratio of 9 and shear-span to depth ratio of 3 were tested at the load increment of 2kN. The load increment was increased after the first crack load. The deflection of the beam specimens was noted down for every increment in the load till the failure. The first crack load, deflection at first crack load, ultimate load and deflection at ultimate load were noted down and the crack pattern was marked on the beam. The companion cubes were also tested simultaneously in compressive testing machine (CTM) to evaluate the compressive strength of concrete on the same day of testing of beams. The loading arrangement is shown in Fig-15 and the failure specimen is shown in Fig-16.
In order to conduct the analysis of confined steelconcretecomposite beam (CSCC Beams) the knowledge about the material properties, mix adopted and compressive strength is essential. Hence experiments were conducted on materials, specimen of concrete cubes and cold formed sheet to understand the behaviour of materials under composite action.Cement: Cement conforming to IS 1489 (part-1):1991, Birla Plus, Premium composite 53 grade cement is considered for the concrete mix.Fine Aggregate: The fine aggregates used for the entire specimen were natural river sand complying with the requirements of IS 383:1970. Sieve analysis was conducted using 2.36mm and it was found that sand was conforming to zone-II grading.Coarse Aggregate: Coarse Aggregate used for making the concrete was as per Indian Standards specifications 20mm. Water: Potable water was used for mixing concrete and for the curing of cast specimens.Reinforcement Bars: Fe 415 bars are used at bottom to take care of temperature effects and their properties were tested in the computerized UTM of 100 tonnes capacity.
The research of Holschemacher et al. (2010) aimed to check how the properties of concretebeams with steel reinforcing depend on the fibres to prevent similar failures that are typically seen in concrete. Eighteen beams (150 mm 150 mm 700 mm) were cast with three different fibre contents, all with less than 1% of volume. Two different reinforcing bars (2 6 mm and 2 12 mm) and three types of fibres were selected: two straight fibre types with end-hooked having different ultimate tensile (1100 MPa) and one corrugated fibre type (2000 MPa). The fibres had an aspect ratio of 50. The concrete compressive strengths ranged between 67 MPa and 115 MPa. The maximum aggregate size of the concrete used was 32 mm, which was shown to have caused a reduction in the effectiveness of fibres within the failed cross sections. It was also observed that there is a dependence of the post-cracking load on the fibre content. Specimens with a fibre content of 60 kg/m 3 with longitudinal reinforcement failed in compression only. The authors concluded that for all selected fibre contents; a more ductile behaviour and greater load capacity in the post-cracking stage were achieved. Due to the fact that this study investigated such small-scale specimens to be structurally evaluated, a further research on the use of normal-strength fibre with end hooks in full-scale beams was recommended.
Concrete is a lot more difficult to model in a finite element package. Numerous people have come up with different methods and formulae in an attempt to make a thorough algorithm to mimic the behaviour of concrete, both in compression and tension. Unlike steel, concrete does not have a homogonous makeup. Concrete itself is a composite structure. It is consists an aggregate material that is interlocked together and bound with cement. Aggregate interlock is complex and inconsistent, adding complexity to the theoretical modelling of concrete. Adding to the complexity is the difference that concrete curing or vibration makes to the strength of the concrete. Therefore, an adequate concrete model needs to be utilised to ensure that the required reliability is obtained.
Figure 10a-b compares the concrete compressive strains recorded by the top gauge fixed on the beams´ faces. In these plots, the failure of the unconfined control beams is represented using stars. Unfortunately, the strain gauge of the SSTT-confined beam B50-1-C detached prematurely as it was subjected to excessive compression. As a result, the effectiveness of the SSTT at enhancing the ultimateconcrete strain in beams B50-1 cannot be assessed. However, the results for beams B50-2, B80-1 and B80-2 indicate that the use of SSTT enhanced the ultimateconcrete compressive strains (at beam failure) by up to 68% (see beam B80-2-30). These results can be justified by analysing the way HSC crushes in compression, which is captured by its uniaxial stress-strain relationship. Initially, concrete expands laterally due to a relatively constant Poisson’s ratio (0.15-0.20). The Poisson’s ratio increases marginally with the stress as microcracks develop due to lateral strain. Just before 85% of its capacity,
The load-mid span deflection of composite truss beams were measured by using a dial gage at the centre of truss. The different behaviour for all tested beams was taken due to the various formatting of specimens in concrete. So load- deflection curves for all specimens was made by three stages; the elastic stage where linear response was presented, elastic-plastic stage after first cracking and plastic stage where nonlinear response noted Also, this stage included failure. Figure (4) represents a comparison of the load-deflection curve for all specimens. It has been observed that the flexural stiffness and slope of the curve for concretestrength 50 MPa larger than the curves of other strength. While 35 and 25 MPa strength have more ductile in behavior of load-deflection curves.
A composite beam (concrete-steel) can be pre-stressed, by the tensioning high-strength tendons. Pre-stressing a composite beam can introduce internal stresses into the member cross sections. It can be carried out for simple and continuous compositebeams. In the positive moment region, the steel beam is usually pre-stressed before the concrete is cast because the negative moment induced by pre-stressing may be used to counteract the positive moments caused by the concrete’s self-weight. In the negative moment region, the steel beam and concrete slab can also be pre-stressed either separately or jointly along the top flange before or after casting of the deck Saadatmanesh 
Previous research has been done on prestressed steel and concretecompositebeams with external tendons such as by Saadatamanesh(1989) , by Saadatamanesh(1989) and Ayyub(1990) , Nie J.(2007) , Zona A.(2009) and Chen Sh.(2009) In this paper, a 3D nonlinear finite element model using the finite element program ANSYS version 12.0 has been developed to account for the non-linear behavior in compositebeams prestressed with external tendons. To examine the model verification was done using the experimental results of Saadatmanesh et al. Saadatmanesh (1989)and Ayyub et al. Ayyub B (1990).Using those models, numerical analysis was performed and compared with the experimental results.
Unlike floor slabs of building, RCC shells require much less steel reinforcement to take care of tensile stresses developed. From the view point of ultimatebehaviour of shell structures analysis considering presence of steel reinforcements is thought to be of importance. Paper deals with linear elastic behaviour and elasto-plastic behaviour of RCC shells subjected to uniform vertical surcharge over the top surface and the longitudinal thrust in the span direction. Besides varying the lengths of shells for a fixed section of shells three degree of reinforcements are considered. Finite element analysis is performed employing 4 noded plate elements for conduction a parametric investigation in the form of various spans. Results of analysis reveal that so far as elastic behaviour is concerned the difference between concrete and RCC shell is negligibly small. However, elasto-plastic behaviour reveals that in general RCC shell has higher capacity compared with that of concrete shell.
Compositeconcrete-trapezoidal steel plate slabs are wid- ely used structural elements in buildings and bridges. During the placement of concrete the trapezoidal steel plate replaces panelling, while upon hardening of con- crete the two materials work as a composite slab, the steel plate representing the reinforcement. For the better vertical load redistribution, concrete is additionally rein- forced with a steel mesh at the upper part of the cross-section (here called the flange). The reinforcement in the web of the concrete part of the section needs rarely to be applied for non-accidental actions. By contrast, when the composite slab is exposed to fire, the steel plate is directly exposed to high temperatures resulting in a substantial decrease of its bearing capacity. The rein- forcement in the web and its position within the concrete slab then become essential. In fact, both the position and the area of the additional reinforcement turn out to be