Full-scale Experimental Tests Research Articles

Predictive analyses for aerodynamic investigation of curtain walls

The paper investigates structural deformation of a stick curtain wall system under full-scale experimental tests. In particular, the wind-façade interaction is discussed through data given by a wind tunnel campaign. European standards for assessment of façades generally foresee to check façade air permeability and wind action resistance by applying a uniformly distributed pressure over the surface. These are unrealistic tests since it is well known that wind distribution can be affected by the building aerodynamics and atmospheric turbulence that generally result in a not uniformly distributed pressure over a surface. In addition, maxima and minima are not simultaneous during wind flow action. This generates an out-of-plane torsion of façade transoms caused by different deformation of the mullions. Elastomeric gasket deformation, as a consequence, may increase façade air permeability. This aspect is neglected by current codes. To investigate this aspect, a numerical FE model was calibrated by full-scale experimental tests and analyses were carried out to compare façade deformation under pressure tests. Six different load combinations were proposed through the investigation of spatial correlation of pressure coefficients time histories acquired in wind tunnel tests on sixteen different geometries of building and two wind angles. In particular, buildings with rounded and angular plan shapes were investigated. Results show a significant difference in structural deformation of the façade between the six load conditions and in particular, a noteworthy deformation between adjacent mullions causing torsion of the transom connected to them.

Full-Scale Experimental Test Production of High-Basicity Sinter in the Enakievo Metallurgical Plant Sinter Shop

We describe the results for full-scale experimental test production of high-basicity sinter (basicity 2.0–5.0) at the Enakievo Metallurgical Plant Sinter Shop. As sinter basicity increased from 2.0 to 5.0, the iron content of the sinter decreased from 53.05% to 32.24%, and the ferrous oxide concentration decreased from 17.55% to 9.29%. However, the strength specifications of the sinter were improved: The concentration of 0–5-mm fines decreased from 19.32% to 15.89%, and the yield of +5 mm size class in a drum test increased from 65.9% to 72.3% through optimization of the sintering process parameters. The use of high basicity sinter in blast-furnace smelting reduced the specific consumption of lime in the blast-furnace charge from 233.9 kg/metric ton of cast iron (at sinter basicity 2.0) to 103.5 kg/metric ton (at basicity 4.5) and, correspondingly, the specific feed rate for coke during castiron production decreased from 538.1 kg/metric ton to 476.6 kg/metric ton.

Full-Scale Experimental Testing and Postfracture Simulations of Cast-Steel Yielding Connectors

AbstractThe cast-steel yielding connector (YC) is a yielding fuse device designed to dissipate earthquake energy through inelastic deformations in specially designed distributed yielding regions, w...

Bimodulus bending model for bamboo poles

The building industry is currently under pressure to transit from non-renewable materials with high embodied energy towards natural and sustainable options. Bamboo poles are some of the most promising renewable structural elements, but their formal utilisation in construction requires the development of appropriate analytical models and new design tools to address their challenging natural and organic nature. Considering the composite nature of bamboo poles and the properties of their high-strength sclerenchyma fibres and parenchyma matrix, this paper presents the formulation of an analytical bimodulus model to determine the cross-sectional strain and stress distribution in bamboo poles in bending. This model was validated through full-scale experimental four-point bending tests on Moso (Phyllostachys pubescens) bamboo poles suggesting a constant tensile elastic modulus of fibres for this species.

A novel steel damping system for rockfall protection galleries

A new steel damping device is proposed to achieve an effective solution for rockfall protection galleries. The system consists of an assembly of cold-formed steel crash boxes, namely Collapsible Tubular Element (CTE), with a transversal section and a length designed to assure, under axial loads, a compressive plastic deformation (folding) without the need of any guide means. Assembled in groups to create a modular cushion, the system reduces the deceleration and the derived impact force due to an impacting block mass during a rockfall event. The influence of both the system module configuration (number of CTEs, presence of restraining cables) and the boulder parameters (mass, angle, and velocity at the impact) is investigated, and a Dynamic Finite Element analyses, along with a full-scale experimental test, have been carried out to evaluate the system performances. The obtained results indicate how the proposed system mitigates the dynamic amplification of the forces transmitted from the impact point to the roof slab, with a mean value of the impact force increased by only 2% within the damping cushion, showing, if compared with the mainly adopted damping cushion systems, a drastic reduction of both impact force and dead load on the gallery's roof. Finally, due to its dimensional stability, the proposed damping device is not affected by compaction over time and by the consequent increase of the impact force. • A new steel damping device is proposed to achieve a more effective, robust, and lightweight solution for rock sheds. • The system consists of assembles cold-formed steel crash boxes, namely Collapsible Tubular Element. • Assembled as a modular cushion, the system reduces the deceleration and the derived impact force due to an impacting boulder. • Dynamic FE analyses, as well as a real-scale experimental test, have been carried out for evaluating the system performances. • The system shows improved performance over the mainly adopted damping cushion systems, including the most innovative ones.

Full-Scale Experimental Verification of UHPC-RC Composite Slab Culvert with a Clear Span of 8 m

To enhance the structural performance and durability of a conventional reinforced concrete (RC) cover slab over a culvert as well as to improve its spanning ability, this paper presents a novel ultrahigh-performance concrete (UHPC)-RC composite cover slab with a clear span of 8 m. The inverted prefabricated UHPC single-Tee or double-Tee beam was placed at the bottom of the cast-in-place normal strength concrete to form the UHPC-RC composite cover slab. A full-scale experimental test on the UHPC-RC composite cover slab was conducted to explore and quantify its mechanical performance. The structural characteristics of the slab, such as failure mode, moment capacity, flexural stiffness, concrete strain distribution, and cracking behavior, were experimentally investigated. The results indicated that, compared to the conventional RC cover slab, the UHPC-RC composite cover slab exhibits a typical flexural failure with a higher cracking resistance, flexural stiffness, flexural capacity, and ability to restrain the propagation of the cracks. An optimized scheme is successfully applied to the practical project. Field testing during the construction process was conducted to investigate the flexural performance of the new composite structure. The results indicated that the structural behavior of the UHPC-RC cover slab aligned well with its predicted values, demonstrating the effectiveness and feasibility of using the UHPC-RC composite cover slab in practical engineering applications.

Experimental and Numerical Studies on the Mechanical Performance of a Wall-beam-strut Joint with Mechanical Couplers for Prefabricated Underground Construction

This paper investigates the nonlinear behavior of wall-beam-strut joints with mechanical couplers, which are proposed for prefabricated underground constructions, under monotonic and cyclic loading conditions using full-scale experimental tests and three-dimensional finite element modelings. The nonlinear behavior of the joint is discussed in terms of the load–displacement curves, concrete cracking distributions, and strains in the reinforcements obtained from both the experimental tests and the numerical modeling. The comparison indicates that the trends of both load–displacement curves are similar, although the cracking, yield and ultimate loads of the joints determined by the numerical modeling are 2.5% lower, 2.6% higher and 3.8% higher, respectively, than those determined by the experimental tests. The numerical simulation can capture the concrete cracking process in the joint in the early loading stage but cannot accurately model the crack distribution in later stages. Moreover, the reinforcement strains and the skeleton curve from the numerical modeling show the same tendency as those from the experimental test, but it is difficult to compare their exact values, especially after yielding. The differences are believed due to the fact that the numerical modeling idealizes the materials and fails to model the slippage between the reinforcements and concrete after the concrete cracking. On the basis of the experimental and numerical investigations, it is concluded that the proposed wall-beam-strut joint has not only an ultimate bearing capacity that is at least 3 times higher than the design load but also a good ductility. Therefore, the design of the wall-beam-strut joint satisfies the requirements for the prefabricated underground construction.

Verification of failure mechanisms and design philosophy for a bolt-anchored and fibre-reinforced shotcrete lining

Abstract Falling or sliding of loose blocks is one of the most common failure modes in a rock tunnel. For tunnels in hard and jointed rock, fibre-reinforced shotcrete (sprayed concrete) in combination with rock bolts is one of the most commonly used supports to prevent such failures. The structural behaviour, and especially the failure, of this type of rock support, is complex and involves several failure mechanisms; such as cracking of the shotcrete and interface failure along the shotcrete-rock, bolt-grout and rock-grout interface. Therefore, rock supports are normally designed using analytical solutions based on the independent failure modes. However, these failure modes are derived based on experimental testing and the assumption that no interaction between the failure modes occur. This assumption has not been verified. Therefore, this paper presents a numerical model capable of simulating the failure of a bolt-anchored and fibre-reinforced shotcrete lining. The model includes bond failure between shotcrete and rock, cracking of the shotcrete and pull-out failure of rock bolts. The structural behaviour for each failure mode and the complete structure have been verified against experiments from the literature. This shows that the model is capable of simulating the different phases of failure, and show good agreement with results from full-scale experimental tests from the literature. Furthermore, results from the numerical simulation confirms that the design of the shotcrete lining can be based on individual failure mechanisms. Moreover, it was shown that a design based on the residual strength of the fibre-reinforced shotcrete is conservative compared to a design based on the bond strength.

Stability performance of thin-walled pultruded beams with geometric web-flange junction imperfections

Abstract The current paper investigates the role of initial imperfections at web-flange junction on the lateral torsional buckling behavior of pultruded fiber reinforced polymeric beams. This study is based on experimental and numerical results, which are developed in two main steps: perfect beams and beams with initial imperfections at the web-flange junction. In the first step, small-scale tests are carried out to calculate the mechanical properties of the composite section. Perfect and imperfect pultruded I- and C- shaped beams are subjected to full-scale experimental tests under an applied four-point bending load with a total lengths varying from 1500 to 3000 mm, and 2500–3500 mm for the I- and C-beams, respectively. The end conditions of all beams studied are simply supported. Perfect beams are tested to investigate their dominant failure mode, as well as the impact of lateral bracing on the failure modes. While, imperfect beams are tested to determine the effect of initial imperfections on the lateral-torsional buckling capacity and failure mechanisms.

Longitudinal box-beam bridge joints under monotonic and cyclic loads

Abstract Longitudinal joints used for connecting box beams in bridge superstructures are prone to the formation and propagation of cracks, causing various structural performance issues and durability concerns. Among possible solutions, the use of shrinkage-compensating cement concrete along with joint reinforcement has been investigated in the current study through full-scale experimental tests and supporting numerical simulations. The shrinkage-compensating cement concrete offered the capability of producing controlled compressive stresses during the early stage of hydration, counteracting detrimental tensile stresses that originate from the shrinkage of concrete. Longitudinal and transverse reinforcements were also included in the joint to ensure the proper transfer of forces. The response of the full setup was evaluated under five million load cycles, including various loading protocols and boundary conditions. The measurements recorded from the experiments consisted of strains and deflections at critical locations. To expand the scope of this investigation and understand the effect of interfacial bond strength and joint reinforcement, a set of numerical simulations were also performed. Through a new combination of concrete mixture and reinforcement detail, this study provided a holistic strategy to resolve the long-standing issue of degradation of longitudinal joints in box-beam bridges.

Rotational Capacity of Bolted Double-Web-Angle Beam-Column Gravity Connections through Full-Scale Experimental Testing

AbstractDouble-web-angle beam–column connections are used extensively for gravity framing in steel buildings. Although they are designed to resist shear and to allow rotation, they still possess mo...

A Discrete Element Model for Masonry Vaults Strengthened with Externally Bonded Reinforcement

ABSTRACT The paper investigates the effectiveness of two-dimensional Discrete Element Method as a tool for structural analysis of arches provided with buttresses and backfill and strengthened with externally bonded reinforcement. Masonry vault and buttresses are modelled as an assembly of 2D rigid blocks interacting through non-linear contact joints, the backfill is discretized into deformable elastic-plastic triangular elements, while the reinforcement is modelled by means of truss elements bonded to the substrate through non-linear springs. A parametric analysis on the influence of material parameters and the effect of the discretization of the backfill is carried out, and the outcome of different reinforcement systems, consisting of Steel Reinforced Grout applied either at the intrados or at the extrados, are analysed. The comparison with experimental full-scale tests proved the ability of the numerical approach to capture hinges position, load bearing capability, as well as the increase in deflection and load capacity provided by the reinforcement.

Improving fatigue resistance of railway axles by cold rolling: Process optimisation and new experimental evidences

Cold rolling is a relatively simple process known as a method to increase the surface hardness and the mechanical fatigue resistance of metal components by the introduction of residual compressive stresses. Cold rolling is also particularly convenient as it is applied in the final part of the manufacturing process. Despite the process being quite common in the manufacturing of various mechanical components, very limited information is available about the actual advantages that are achievable on safety critical components like railway axles. This paper focuses on both optimisation of the process parameters adopted on the Lucchini RS and on the advantages that are obtained when a well calibrated process is applied. The process is optimized by an analytical model, validated by means of an extensive number of residual stress measurements using the X-ray Diffraction method, that estimates the residual stress profile that is generated under the surface depending on different parameters (force, roller geometry, roller feed, axle geometry and steel grade). An overview of various advantages, demonstrated by an extended series of experimental full-scale tests, is then shown: an increase in the fatigue limit even in the presence of artificial micro-notches and corrosion fatigue. An analysis of the driving force at the crack tip is able to confirm the experimental evidences.

Lateral performance of a new hybrid CFS shear wall panel for mid-rise construction

ABSTRACT Hybrid shear walls composed of cold-formed steel (CFS) open sections and square hollow sections (SHS) have recently attracted attention for lightweight midrise buildings, as a result of their relatively strong lateral load-bearing performance. A new hybrid CFS shear wall system with SHS truss skeleton is presented in this study in order to improve the lateral behaviour of lightweight steel frames, in compliance with standard codes. For this purpose, eleven full-scale experimental tests were conducted to assess the shear resistance, stiffness, ductility, and energy absorption of the proposed wall panels. The study also investigates the failure modes of the hybrid walls and suggests solutions for improving the existing structural weaknesses. The results showed that employing the SHS truss configuration for one side of the light steel walls can significantly enhance the energy absorption, compared to the traditional CFS walls. The SHS truss also has a considerable effect on decreasing the chance of chord stud buckling; i.e. load-bearing capacity. Specimens sheathed with gypsum board offer higher strength and ductility ratio with a few minor localized failures, compared to specimens without sheathing board. The results also indicate that the low strength to weight ratio of hybrid walls makes them a practical solution for mid-rise lightweight constructions.

Energy savings and daylighting evaluation of dynamic venetian blinds and lighting through full-scale experimental testing

Abstract Commercial buildings consume around 20% of the total energy utilized in the U.S. The use of shading devices in buildings has the potential to reduce building energy consumption while also providing a more desirable indoor environment for building occupants. Similarly, lighting device controls help reduce lighting energy consumption as well as internal loads. However, there is lack of full-scale experimental testing of integrated dynamic shading and lighting controls. This study presents full-scale experimental testing data to quantify these energy and daylighting impacts. Testing was performed utilizing two different control strategies, in three different orientations under three different types of sky conditions. The shading device was also used in conjunction with two different types of glazing. An average of 25.4% cooling energy savings and 48.5% lighting energy savings was achieved. Visual discomfort evaluated using Simplified Daylight Glare Probability was prevented more than 85% of time during occupied hours. Improvement in daylight levels evaluated using Useful Daylight Illuminance was also achieved. Finally, analysis of the relationship between the illuminance level measured at the work plane and a ceiling illuminance sensor is performed to translate the real-world applicability of shading device controls.

Full-scale testing on the flexural behavior of an innovative dovetail UHPC joint of composite bridges

This paper presents a full-scale experimental test to investigate the flexural behavior of an innovative dovetail ultra-high performance concrete (UHPC) joint designed for the 5th Nanjing Yangtze River Bridge. The test specimen had a dimension of 3600 × 1600 × 170 mm, in accordance with the real bridge. The failure mode, crack pattern and structural response were presented. The ductility and stiffness degradation of the tested specimens were explicitly discussed. Test results indicated that different from conventional reinforced concrete slabs, well-distributed cracks with small spacing were observed for UHPC joint slabs at failure. The average nominal flexural cracking strength of the test specimens was 7.7 MPa, signifying good crack resistance of the proposed dovetail UHPC joint. It is recommended that high grade reinforcement be cooperatively used to take full advantage of the superior mechanical property of UHPC. A new ductility index, expressed by dividing the ultimate deflection by flexural cracking deflection, was introduced to evaluate the post-cracking ductility capacity. Finally, a strut-and-tie (STM) model was developed to predict the ultimate strength of the proposed UHPC joint.

Verified and validated design curves and strength reduction factors for post-tensioned composite steel-timber stiffened wall systems

Abstract Viability of timber-based solutions for projects is often limited by lengthy modelling and preliminary design when compared to traditional systems such as precast concrete. However, sustainability principles are becoming more prevalent in construction with increasing demands for mid-rise buildings constructed through automated prefabrication via Design for Manufacturing and Assembly (DfMA) techniques. Considering this, this paper introduces and presents design curves for Post-Tensioned (PT) Composite Steel-Timber stiffened wall systems under axial loading. Notably material efficient, they consist of a stiffened engineered timber panel, having half the typical minimum thickness of Cross-Laminated Timber (CLT). Composite action is gained through integrally stiffening the panel with timber studs and steel Square Hollow Sections (SHS), which house a PT rod. The post-tensioning facilitates vertical panel to panel connections for quick on-site assembly, permanent tie-down and self-centering rocking mechanism functionality. A full-scale experimental testing program was conducted in conjunction with analytically verified and validated finite element models. Parametric changes include: level of post-tensioning, number of stiffeners, thickness of panel, height of the wall and applied load. Highly versatile yet simple design curves have been developed from an exhaustive set of incremental results. In addition, a strength reduction factor capturing the effects caused by post-tensioning is proposed. With these, a simple design procedure has been outlined for quick feasibility analysis and preliminary design. That is, for a desired load capacity and level of post-tensioning, the optimal system configurations is given. Likewise, for a chosen configuration and level of post-tensioning the allowable axial load is given.

Behaviour of retrofitted masonry walls subjected to blast loading: Damage assessment

Abstract The response of brick masonry walls against blast loads has become an important topic in recent years. The debris from masonry walls or their collapse can become a major hazard when the main structure does not collapse. In this paper, a damage assessment of brick masonry walls subjected to blast loading is presented. For this purpose, three different retrofitting solutions have been tested in four full-scale experimental tests and compared with a control non-reinforced brick panel. The protective solutions which have been considered can be applied in a simple way, both in new or existing buildings. For the evaluation, several parameters have been collected and analyzed combining visual observations and analytical methods. Damage levels range from moderate damage to collapse. Among the three types of retrofitting solutions tested, results show that two of them were effective for strengthening brick masonry wall panels against blast loading.

Investigating the scaling of masonry structures in a blast environment

Abstract Full-scale experimental testing of masonry response to blast can be challenging with the requisite need for significant measurement area in conjunction with high construction and material costs. This paper investigates the use of dynamic similitude to produce reduced-scale masonry structures which model the damage state and debris distribution of a full-scale counterpart due to blast loading. An investigation into the fundamental physical components of masonry response to blast loading facilitated the development of a new scaling methodology which maintains the ratio of lateral and vertical force components as prescribed by dynamic similitude. It is shown that this can be accomplished by using a reciprocal scale factor for the reduced-scale structure’s density. Computational models of full and reduced-scale masonry response to blast loading were produced with the Applied Element Method (AEM) to verify the underlying theory of the proposed scaling methodology. These utilised single-storey cuboid structures with non-responding roofs and half-thickness stretcher bond construction. Computational Fluid Dynamics (CFD) models of blast wave interaction with the masonry structures were defined at a range of peak overpressures, enabling a remap procedure into AEM. Importantly, AEM models utilised a constant 1:2 scale factor with masonry material parameters for commercially available units, demonstrating the practical applications of this scaling methodology for blast trials. Analysis of the AEM models demonstrated close qualitative agreement in damage state for full and reduced-scale structures at 55 kPa and 110 kPa peak free-field overpressure. These results also indicated agreement for a range of failure modes with the 110 kPa model showing front-panel collapse versus the 55 kPa model which indicated partial front-panel deflection. Chi-square analysis of the resultant debris distribution at 110 kPa indicated quantitative agreement for the relative quantities of bricks found within the rubble pile as a function of their original panel wall location.

Field experiments on laterally loaded piles for an offshore wind farm

Abstract Pile foundations are widely used to support offshore wind turbines due to their cost effectiveness and rapid constructions. Offshore piles must be designed with enough capacity to withstand overturning moments caused by wind turbines and other environmental factors such as wave excitations and extreme winds. In this study, a full-scale field experimental test is undertaken to determine the pile behaviour under various lateral loading conditions. A distributed fiber optic sensing technology is used to measure strains along two instrumented piles. The bending moments and lateral deflections are calculated from distributed fiber optic sensors, and then analysed with the various p-y methods. Field measurements indicated that for two offshore piles ZK01 and ZK28 with diameter of 2 m and length of 71.5 m and 77.5 m, the maximum lateral movements under a given lateral load of 800 kN were 369.1 mm and 351.7 mm, respectively. The maximum bending moment occurred at 6.5 m and 5.5 m below seabed level with the corresponding depth of 12.15D and 11.95D for pile ZK01 and ZK28, respectively. The position of “zero crossing” of soil resistance for two instrumented piles is almost the same, even though the piles have different lengths. The lateral deflections and bending moments of the two instrumented piles are predicted by the API and hyperbolic method, which indicates that the hyperbolic method yields larger prediction errors than the API method. A modified p-y approach is then proposed for more reliable predictions when compared with field measurements.