Shear Connection System Research Articles

El Centro de Diseño de Barcelona

The most characteristic element of the new Barcelona Design Centre is the 35m span, 20m high and 20m wide cantilever projecting over Las Glorias Catalanas square. The construction method used in its execution (cantilevered erection in a congested urban area), so as the characteristics of the bolted steel structure and the way it is anchored to the concrete core walls, employing post-tensioning systems and stud shear connectors, transform this building into a singular structure in the field of construction. At the same time, the specific tests carried out to assess the suitability of the bolted connections, mainly those developed for the characterization of the friction coefficient used in design are of interest, so as the criteria adopted for the design of post-tensioning and shear connection systems used for anchoring the structure to the concrete core of Block 2.

Innovative Timber-Concrete Composite Structures with Prefabricated FRC Slabs

This paper concerns the development of innovative composite floor systems, comprising timber beams and prefabricated concrete slabs. For the development of this new system, two properties were regarded as vital, as follows: (1) good stiffness, and (2) a high degree of prefabrication. Shear connection systems installed using completely dry processes were used. Innovative and very efficient materials, such as fiber-reinforced concrete (FRC) and modified wood, were used for the manufacture of the specimens. The research reported in this paper was conducted in two phases, as follows: (1) the mechanical properties of different shear connectors were investigated (Phase A), and (2) on the basis of these experiment’s results a second investigation was carried out in order to study the behavior of full-scale timber-concrete composite slabs (Phase B). During Phase A four different configurations, with a total of eight specimens, were laboratory tested in shear. During Phase B two full-scale floor elements, each with a different shear connection system, were laboratory tested in bending. The two shear connector systems used in the investigation were (1) shear anchor-keys of furfurylated wood, and (2) inclined steel tubes. Both of the proposed connection systems performed more than satisfactorily, showing a very high degree of composite action even at load levels close to the failure load. Moreover, it appeared that the assembling of the prefabricated fiber-reinforced concrete slab with the underlying beams occurred in an extremely easy manner.

Tests on glulam–CLT shear connections with double-sided punched metal plate fasteners and inclined screws

A new shear connection system was tested in order to be used in off-site manufactured cassette floor elements made with glulam beams and cross laminated timber (CLT) panels. This type of floor element can present advantages from weight, structural and assembly point of view in multi-storey timber construction. The shear connection proposed is made of double-sided punched metal plate fasteners, connecting CLT and glulam members to form a T-cross-section. Inclined screws are used in combination with the double-sided nail plates to secure the shear connection. Shear test results are presented and compared with a simple calculation model for estimating the mean load-carrying capacity and stiffness of the combined joint according to methods available in the literature.

The New Barcelona Design Centre

A characteristic element of the new Barcelona Design Centre is the impressive cantilevered hall of 35 m span, 20 m height and 20 m width projecting over Las Glorias Catalanas square. The construction method used in its execution (that is, cantilevered erection in a congested urban environment), the special characteristics of the bolted steel structure and the way it is anchored to the concrete core walls, employing post-tensioning systems and stud shear connectors, transform this building into a very interesting structure in the field of construction. Some of the specific tests carried out to assess the suitability of the bolted joints, primarily developed for the characterization of the friction coefficient used in the design, led to some important conclusions for the design of preloaded bolted connections at ultimate limit state (ULS) to be included in the codes of practice. At the same time, the criteria adopted for the design of post-tensioning and the shear connection system used for anchoring the cantilevered hall to the concrete core of Block 2 are of particular interest.

DEVELOPMENT OF AN OPTIMUM PRE-FOUNDED COLUMN SYSTEM FOR TOP-DOWN CONSTRUCTION

In this work, circular concrete-filled steel tubular (CCFT) columns, rather than the more popular H-shaped columns, were suggested as pre-founded columns for top-down construction. In addition, a novel shear connection system with headed stud shear connectors between the CCFT columns and the flat slabs was developed. It was noted that a CCFT column with a design compressive strength similar to that of an H-shaped column without consideration of length effects can be easily installed, even into a smaller borehole. Furthermore, compared to the H-shaped column, less steel is required for the CCFT column. It was shown that the amount of steel needed can be reduced by decreasing the wall thicknesses or diameters of the CCFT column depending on the exposed length of the column during excavation. The fillet-welded joint of the developed shear connector system was also tested before its in-situ application. The test results revealed that the joint possessed sufficient shear and deformation capacities. The CCFT column with the developed shear connection system was ultimately applied to an actual top-down construction process. The good constructability of the CCFT column system and reductions in construction costs and time were confirmed.

Shear connection system and performance evaluation of FRP-concrete composite deck

Strong composition between FRP and concrete is an indispensable prerequisite to achieve the structural integrity of FRP-concrete composite deck. Accordingly, this study evaluates experimentally the behavioral characteristics of such shear connection systems realized by coarse sand coating and concrete wedge. The results show that coarse sand coating develops composite performance close to perfect composition in the shear direction but exhibits weakness against normal split. On the other hand, concrete wedge appears to be an efficient solution to resolve such problem. Therefore, a new shear connection system combining coarse sand coating and concrete wedge has been conceived and test revealed that the new shear connection system provides equivalent static performance together with significantly improved fatigue performance compared to the coarse sand coating composition. Following, the shear connection system combining both coarse sand coating and concrete wedge constitutes an efficient solution satisfying the strong composition requirement for the structural system.

Stiffness and Strength Evaluations of a Shear Connection System for FRP Bridge Decks to Steel Girders

This paper reports on research investigating a nongrouted sleeve-type connection used to attach fiber-reinforced polymer (FRP) decks to steel girders. The connection system was investigated for stiffness, strength, fatigue resistance, and degree of composite action. Static and fatigue tests were conducted first at the component level on push-out specimens to obtain P-Δ (load-displacement) and S-N (stress range–fatigue life) relationships, from which design formulas were developed. Then tests were conducted at the system level on a 1∶3 scaled-bridge model by using this sleeve-type connection, and the results showed this shear connection can satisfy requirements from AASHTO specifications for fatigue, strength, and function. Further, three-point bending tests were conducted on a T-section model cut from the scaled bridge, and approximately 25% composite action was achieved for two different connection spacings. The structural efficiency of this shear connection is shown, and this connection design is applie...

Flexural behaviour of multi-span GFRP-concrete hybrid beams

This paper presents results of an experimental and analytical study on the flexural behavior of multi-span GFRP-concrete hybrid beams. Previous investigations showed the viability and technical advantages of connecting GFRP pultruded profiles to concrete elements in GFRP-concrete hybrid cross-sections, used in simply supported structural elements. The objective of the present study was to investigate the flexural behaviour of the GFRP-concrete hybrid solution in continuous structural elements, in which, in addition to the lower deformability when compared to isostatic systems, the cross-sectional and structural redundancies may also allow for a certain pseudo-ductility at failure. With this purpose, a set of design equations was derived in order to analyse the flexural behaviour of continuous hybrid beams, subjected to positive and negative bending. Those equations were used to design two continuous 3-span and 2-span hybrid beams with a bonded shear connection system, which were tested in bending. The flexural tests allowed us to investigate the serviceability behaviour and the failure mechanisms of multi-span GFRP-concrete hybrid beams.

GFRP–concrete hybrid cross-sections for floors of buildings

The development of flooring systems with improved durability and higher speed of construction has, in recent years, led to the study of new structural solutions. This paper presents the results of a study of an innovative solution for floors of buildings, with glass fibre reinforced polymer (GFRP) pultruded profiles connected to concrete elements, with either steel bolts or an epoxy adhesive layer. Shear connection tests were first conducted on GFRP I-profiles connected to concrete, using both shear connection systems. The results of those tests were then used to design simply supported beams with a GFRP–concrete hybrid cross-section, which were tested in bending with different spans and load arrangements, comprising two alternative shear connection systems. The experimental programme included also investigations on the strength of different configurations of supports of hybrid beams. In order to better understand some of the experimental results, namely the debonding mechanisms observed at the interface of hybrid beams with bonded shear connection systems, numerical analyses were performed to investigate the stress state at the interfaces. Experimental and numerical investigations showed the viability of using GFRP–concrete hybrid cross-sections in floors of buildings, either for rehabilitation or for new constructions, and proved that adequate constructive detailing can significantly improve the performance of the proposed system.

Composite Behavior of Precast Concrete Full-Depth Panels and Prestressed Girders

The authors evaluate the composite behavior of a bridge section consisting of a full-depth concrete slab that is connected by threaded steel bolts to an AASHTO-type concrete I-girder. The research conducts 13 push-out tests on specimens having shear pockets in the slabs to show both horizontal shear strength capacity and the behavior that threaded steel bolts exhibit when used as shear connectors to achieve composite action between the precast concrete panels and precast concrete girders. The specimens, cast and tested under static loading conditions, are used to determine the ultimate strength and failure mode of the shear connection system. Steel bolt length, along with their number, configuration in the shear pocket, and spacing are also examined. Results show that threaded steel bolts allow for full composite action between the precast concrete panels and precast concrete girders. The authors also note that their results, when applied to the load and resistance factor design guidelines of the American Association of State Highway and Transportation Officials, point to the Association's conservative estimate of design strength.