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In the cyclic racking evaluation of curtain wall systems, physical testing with instrumentation is the standard method for collecting performance data by most design professionals. The resulting testing of full-scale mockups can provide many types of data, including load and displacement values at different stages of loading through failure. While this type of data is valuable for product/system development/fabrication and design, such data can also provide a means for simulation validation of the curtain wall cyclic performance under simulated earthquake loading. Once the simulation study is validated using the test results, then parametric studies by designers can be conducted with greater ease, ideally with commercial software packages, without the need for testing. For the results of this research study, a practical industry formulated finite element modeling (FEM) approach was used to predict the performance of the curtain wall mockups. Here, unitized four-sided structural sealant glazing (4SSG) curtain wall system mockups that incorporate a re-entrant corner were subjected to cyclic racking displacements per the American Architectural Manufacturers Association (AAMA) 501.6 Structural Sealant protocol. System performances, including displacements, were obtained from the FEM study and used to calculate the effective shear strain of the structural silicone and the drift capacity of the system. This paper describes the details of the techniques developed for FEM, the analysis results, and shows an example application of the numerical modeling approach for mockups with racking test results available. The goal of this modeling approach was to create and test methods that practicing consulting engineers can quickly conduct in their offices on common commercially available software often available to them.

This paper presents the results of an experimental campaign investigating the seismic behaviour of full-size cross laminated timber (CLT) wall systems with sound-insulated shear-tension angle brackets. The main aim of the study was to investigate the influence of more and less flexible soundproofing bedding under the CLT wall. The paper shows a comparison of lateral load-bearing capacity, displacement capacity, ductility and stiffness obtained from racking tests on uninsulated specimens and specimens with various types of bedding insulation and levels of vertical load. Moreover, an analytical procedure to estimate the lateral load-displacement response of CLT walls with bedding insulation is proposed. This model is verified by direct comparison to the experimentally determined lateral load-displacement backbone curves. The results show that the elastomeric bedding does not have a significant effect on the bearing capacity of the wall system tested, but it reduces the stiffness and increases the displacement capacity. Due to the large decrease in stiffness, the insulation causes an overall reduction in ductility. The analytical estimation proposed was able to capture the reduction in lateral stiffness and adequately predict the load-bearing capacity.

Timber-framed shear walls are designed to resist the lateral loads on a building from wind and earthquake. Many regions around the world have developed standard test methods for evaluating the performance of timber-framed shear walls. Currently, Australia has no such standard test method for timber-framed shear walls. The aim of this study is to develop a standard loading protocol for evaluating the performance of timber-framed shear walls in Australia that is informed by the concerns of both earthquake engineers and wind engineers. To achieve this aim, the key objective of this study is to compare the performance of a standard timber-framed shear wall under three different monotonic (groups M1, M2 and M3) and four different cyclic (groups C1, C2, C3 and C4) loading protocols according to their respective standards. The number of test panels in each group was three ( 3 ) for a total number of 21 individual tests. Structural performance characteristics of the standard test panel, such as ultimate and yield strength and global stiffness, were found to be strongly dependent on the loading protocol. For example, ultimate strength was lower for test panels subject to monotonic loading (i.e., 5.99 , 6.41 and 6.34 k N / m for groups M1, M2 and M3 respectively) compared to test panels subject to cyclic loading (i.e., 6.70 , 6.73 , 8.03 and 8.11 k N / m for groups C1, C2, C3 and C4 respectively). Internal stiffness was found to be relatively consistent regardless of loading protocol. The higher ultimate and yield performance of group C3 (CUREE protocol) and C4 (Cyclone Testing Station protocol) is statistically significant, at the 5 % significance level, compared to results from all other test methods (i.e., AS1720.1, EN 594, ASTM E564, BRANZ P21 and ISO 16670). Differences in boundary conditions between the loading protocols might explain some of the differences in results; however, this hypothesis is not strongly supported by the evidence. These results are used to inform our recommendations for developing an Australian standard test method for evaluating the structural performance of timber-framed shear walls.

Current design methodologies for underground structures subjected to earthquake action are based on closed-form solutions of the so-called racking coefficient, which relates the soil free-field distortion deformation to the structure distortion deformation. Existent closed-form expressions for this racking coefficient are derived for circular tunnel geometries embedded in an elastic and homogeneous medium, while expressions for rectangular geometries are based on analogies of the circular case. In this paper, a new and intuitive methodology derived from first principles to obtain a closed-form expression for the racking coefficient for rectangular-like tunnel geometries buried at a sufficient depth is presented, and it is shown that it provides a good fit to finite element analyses results. Similarly, a procedure to obtain closed-form expressions for the rocking rotation of the structure, and the racking deformation profile at different distances from the soil-tunnel interface is presented.

This research conducts dynamic time-history analysis and a modified cross-section racking deformation (MCSRD) method to analyze the collapse mechanism of the Daikai Subway during the 1995 Kobe earthquake using FLAC2D. A simplified approach to consider the nonlinear behavior of a structure element is imported and combined with the FLAC2D built-in nonlinear soil constitutive models to accurately consider the nonlinear interaction between the soil material and structure. Based on the proposed framework, the damage evolution process of the Daikai Subway station can be traced by the dynamic time-history analyses. The collapse pattern roughly agrees with field observation. Regarding the MCSRD method, the critical member of the “central column” is identified but the internal forces did not reach its limit state; this may be because inertial force is neglected, which is a characteristic of the pseudo-static method. Therefore, it is recommended to conduct dynamic time-history analysis for a shallow buried tunnel in soft soil because the inertial force may largely influence the seismic characteristics.

Accurately determining the transverse shear stiffness of steel storage rack upright frames is essential in calculating the elastic buckling load, performing earthquake design and serviceability checks. International racking design specifications recommend different approaches to evaluate this stiffness. The Rack Manufacturers Institute (RMI) specification conservatively uses an analytical solution based on Timoshenko and Gere's theory while the European (EN15512) and Australian (AS4084) specifications recommend experimental testing to be conducted. Previous studies have shown that Finite Element Analyses (FEA), solely using beam elements, fail to reproduce experimental test results and may overestimate the transverse shear stiffness by a factor up to 25. This discrepancy is likely attributed to the local deformations occurring at the bolted joints. In this paper, a model to capture the transverse shear stiffness of upright frames is developed using shell elements and advanced FEA. Its accuracy is verified against published experimental test results performed on three commercially used upright frame configurations with lip-to-lip bracing pattern. The model accurately reproduces the experimental stiffness, with differences ranging from 2% to 17%. Based on the FE model, the factors contributing to the transverse shear deformation of the frames are quantified and discussed for both lip-to-lip and back-to-back bracing patterns. For lip-to-lip upright frames, results show that the local deformations at the end of bracing members contributes the most to the shear deformation of the frames. For back-to-back upright frames, bolt bending and axial deformation of braces contribute the most to the shear deformation of the frames. Results from this paper would assist the racking industry in improving their products by focusing on the factors influencing the most the behaviour of the frames.

In tunneling practices, it is vital to have an accurate estimate of the depth of embedment of the tunnel; lining thickness and shape of the tunnel, which enables resisting of stresses; and deformation generated by the surrounding soil under seismic loading conditions. The present study highlights the behavior of shallow tunnel in soft soil under seismic conditions by using the finite element (FE) analysis. The developed numerical model is compared with available analytical solutions. Thereafter, a series of parametric studies are carried out by varying the tunnel embedment ratio, soil-tunnel interface conditions, lining thickness, shape of the tunnel, and input ground motion. It has been observed that distortion in the tunnel lining is dependent on the depth of embedment and the flexibility ratio of the tunnel. Ovaling (in a circular tunnel) and racking (in a rectangular tunnel) are found to decrease significantly when embedment ratio is greater than 2. Nearly 6–18% of greater distortion and 20% of greater bending moment are obtained in the full-slip interface condition when compared to the no-slip interface condition. The maximum induced bending moment in the tunnel lining is directly proportional to its flexural rigidity. An unconventional square tunnel with rounded corners, yields 55% lesser bending moment than the square tunnel under the same seismic loading condition. This study also highlights the importance of the input ground motion characteristics that govern the development of the maximum dynamic earth pressure around the lining of the tunnel, and the heaving of the ground surface just above the crown. The outcomes of the present study will be useful in design through understanding the effects of various influencing parameters that control the stability of the tunnel in soft soil under seismic loading conditions.

This study aims to evaluate the performance of a steel storage pallet racking system equipped with a novel seismic isolation system, which is effective along the cross-aisle direction alone. The isolation system consists of two IsolGOODS® isolators, which are curved surface slider bearings as framed into the European Standards for anti-seismic devices. The efficiency of the proposed device in reducing the seismic effects on pallet racks is investigated. Firstly, uniaxial real-time shake table tests are performed, showing a great reduction of floor accelerations. With the help of a herein validated numerical model, advanced knowledge is obtained. Six accelerograms, two normal-fault records, two pulse-like, and two spectrum-compatible series are selected for drawing generally valid statements. As proposed in this work, the outcomes confirm that the isolation system provides substantial reduction in terms of floor accelerations. In contrast, no up-lift of the base-connections is recorded: the uprights are always engaged in compression. On the whole, the most severe condition comes from the pulse-like record (Emilia 2012), in which displacement demand must be carefully considered while defining the isolators to be put in place.

The progressive failure analysis of wood-frame structures under wind loads requires the resistances of each of the components (such as roof, walls, and connections) as input. The resistance...

This paper presents the results of a continuous monitoring activity of a commercial steel pallet-rack. The first objective was to obtain the real history of the dynamic actions undergone by...

An extensive parametric numerical study was performed after completed experimental campaign of timber-glass hybrid walls (TGW and TGWE). 36 timber-glass models (TG) with different outer dimensions were built and analysed with a goal to capture the basic response of mechanically tested timber-glass walls and to determine the racking stiffness of the calculated numerical models. Timber frame was modelled using linear beam elements with hinges in all four corners, an IGU was modelled as a multilayer shell and finally a layer of adhesive was modelled with linear and nonlinear springs, which were distributed circumferentially around the edge of IGU and connected onto a timber frame. Normal and shear stiffness coefficients for linear-elastic springs were calculated, while for nonlinear springs a special series of mechanical tests on polyurethane (PU) adhesive was performed since a lack of data available in addition to the desired amount of information needed for the numerical analysis. Uniaxial tension, compression and shear tests were made to obtain the results in form of the load-displacement curve, which presented a direct input for nonlinear normal and shear springs of the mathematical model. For each compression and tension mechanical test three specimens were prepared and tested up to rupture, while a double-lap shear test was conducted using two specimens giving two results each. PU adhesive specimens of the first series had dimensions of 50 mm $$\times $$ 50 mm and thickness of 5.0 mm. Mechanical tests were repeated for two additional thicknesses of PU adhesive, namely 7.0 mm and 9.0 mm. After completed experimental investigation on PU adhesive joint, together 108 numerical models with different external dimensions were analysed in commercial code SAP2000. Having the correct information about the stiffness of the single TG shear wall one can calculate the stiffness of the entire timber-glass building built with such walls.

A reliable simulation of soil–structure interaction (SSI) is the precondition for understanding properly the dynamic response characteristics and earthquake disaster mechanism of underground structures. This paper adopts Smoothed Particle Hydrodynamics-Finite Element Method (SPH-FEM) coupled method to address the SSI issue. The coupled method takes advantage of the convenience of SPH in simulating the particle features of soils. The advantages of the presented method are capable of tracking the location information and motion of soils at any moment, and the deformation process inside the near-structure soils can also be captured during an earthquake. Meanwhile, it can also be made use of the accuracy of FEM in handling boundary issues and solving structural dynamics. Analysis results indicate that not only the racking deformation mode is observed, but also a rocking vibration mode that is non-negligible can be found for a rectangular underground structure under transverse seismic excitation. The rocking vibration mode is shown as the incline of top and bottom slabs, which is caused by the asymmetric seismic action on two opposite side-walls resulting from the different soil–structure contact status. The analysis clearly shows that the seismic earth pressure is a result of the interaction between soil and structure in an earthquake. The distribution and magnitude of seismic earth pressure are influenced by the magnitude of soil deformation and soil–structure contact status.

This study documented the case history of the new Sanyi railway tunnel. The New Austrian tunneling method (NATM)-built mountainous tunnel was seriously damaged during the 1999 Chi-Chi earthquake. In order to better understand the vulnerability and the deformation of the underground structure subject to strong ground motion, the modified cross-section racking deformation (MCSRD) method was used to evaluate the seismic performance of the tunnel. The analyses carefully took the nonlinear soil-structure interaction into account in order to derive damage pattern of the tunnel. Based on the analysis results, in addition to the extremely strong ground motion, numerical testing identified the causes of the disaster to include rectangle-like geometry at the refuge section, non-reinforcement of the second lining, and imperfect backfilling. The results also showed that the second lining of the NATM-built tunnel sustained substantial seismic loading and should be suitably reinforced in seismically active areas. The effect of the reinforcement of the second lining was demonstrated with a reinforcement example.

A structural insulated panel (SIP) is an emerging building material with a composite structure; these panels are widely used as wall, floor, or roof members. When used as a wall member, the lateral force resistance is an important index for product design and structural design. In this study, oriented stranded board (OSB) and structural plywood were used as the facing panels, and polyurethane insulated board was used as the core layer. The influences of different wall thicknesses, facing materials, module combinations, and loading methods on the lateral force resistance performance of the SIP walls were systematically investigated. Results show that the ultimate load in the racking test increased linearly with increase in the thickness of the SIP wall. SIPs with structural plywood sheathing obtained higher racking resistance values than SIPs with OSB sheathing. Lateral force resistance of the SIP walls with the 600 mm by 2400 mm module was 13.5% higher than that of the SIP walls with the 1200 mm by 2400 mm module. A decrease in the nail spacing significantly strengthened the lateral force resistance of the SIP walls. There was a 5.7% difference in ultimate shear load values obtained from tests based on the ISO 22452 and ASTM E72 standards. Failure modes of the SIP walls depended on the type of sheathing and the monotonic loading method (direct vs. multi-stage loading). The satisfying shear strengths of the SIP walls obtained in this study provide guidance for the practical use of SIPs as shear walls.

Understanding damage mechanisms and associated facility challenges for curtain wall systems with different boundary conditions is critical in their performance evaluation and selection during the design stage of a building's lifecycle, in particular if vulnerable to earthquake effects. While many different styles and configurations exist, limited research has been conducted on unitized four-sided structural sealant glazing (4SSG) with re-entrant corners under dynamic racking testing conditions. As such, this paper details a study on full-scale unitized 4SSG curtain wall system mockups featuring a re-entrant corner and subjected to cyclic racking displacements. Racking tests were carried out in accordance with the American Architectural Manufacturers Association (AAMA) 501.6 protocol. Glass fallout, sealant adhesive or cohesive failure, and glass cracking failure modes were identified as limit states and corresponding drift levels were determined. Results of these tests on full-scale specimens are presented here and some of the challenges in data collection and accuracy when using a racking facility are discussed.

The modified cross-section racking deformation (MCSRD) method can accurately derive the vulnerability and the deformation of underground structures resulting from different magnitudes of earthquakes; while the nonlinear soil-structure interaction can be determined by numerical calculation. Compared with dynamic analysis, the MCSRD method is a more efficient and simpler way of achieving the seismic performance-based design (SPBD) for underground structures. To better apply the method using FLAD2D, the research includes several numerical examples, which study critical numerical points of the approach. The framework of the MCSRD method to assess the seismic capacity of underground structures will be demonstrated with an example.

International audience; Lime and hemp concretes are used as infill materials manually tamped in timber stud walls or more recently in the form of precast blocks. In either case, the structural design practice of wood frame construction associated with hemp concrete does not assume any contribution of the plant-based concrete whereas it may contribute towards the racking strength of the wall. This work is intended to evaluate the shear behaviour of two different bio-based concretes by means of triaxial compression. Hemp shives and whole rice husks were mixed with a lime-based binder according to the same mix proportioning and mixes were vibro-compacted in cylindrical forms. Then, samples were cured at 23 degrees C - 65%RH before being tested under unconfined and triaxial compression. The triaxial shear test was performed after 60 days of curing on unsaturated specimens under drained conditions at air pressure and for increasing effective confining pressure (from 25 to 150 kPa). It was possible to estimate the shear strength parameters (peak friction angle and cohesion) of the two plant-based concretes. Comparing results, it appears a consistent value of cohesion but a different friction angle related to the binder and the aggregate contributions respectively. This leads to a first analysis of the relationship between the composition of the concrete (plant aggregates cemented with a binder) and its shear strength. Furthermore, the ductility of plant-based concretes is markedly enhanced as the mean effective pressure increases. Finally, the shear strength of plant-based concretes should be considered as part of the design practice of building envelopes.

A numerical parametric study was conducted on diverse soil-rectangular tunnel systems, aiming to shed light on critical response characteristics of rectangular tunnels subjected to transversal ground shaking. Salient parameters that affect the dynamic response, such as: (i) the soil-tunnel relative stiffness and interface properties, (ii) the shape, dimensions and burial depth of the tunnel section, (iii) the soil deposit characteristics, and (iv) the input motion characteristics, were accounted for in this study. This paper summarizes the key findings of this investigation, focusing on the complex deformation modes of the tunnels during shaking, the dynamic earth pressures and the soil dynamic shear stresses developed around the tunnel, and the dynamic lining forces. The numerical results indicated a combined racking-rocking deformation pattern for the tunnels during shaking, while inward deformations of the slabs and the side-walls were also observed for flexible tunnels, when soil inelasticity was encountered. To quantify the racking deformation of rectangular tunnels, a series of numerical racking ratio - flexibility ratio ( R-F ) relations were developed and compared with existing analytical and empirical ones. The rocking response of rectangular tunnels was quantified by means of dimensionless relations ( θ / γ ff -F ), similar to the R-F relations. The soil-tunnel relative stiffness, the interface characteristics and the soil yielding affected significantly the above relations, as well as the dynamic earth pressures, the soil dynamic shear stresses and the dynamic forces developed on the lining during shaking. The presented results lead to a better understanding of the seismic response of rectangular tunnels in soft soil, while the proposed relations contribute towards the improvement of the R-F analysis method.

Conventionally, a flexural plastic hinge is assigned and detailed at the core wall base and coupling beams ends to control seismic responses. This strategy is based on allowing damage to main structural components. To avoid damage to main structural components, an alternative strategy using energy dissipating devices, such as fluid viscous dampers (FVDs), is currently being studied and implemented. In this study, the effect of FVD locations on a 40-storey, high-rise, reinforced-concrete core wall case study building has been studied in detail using non-linear response history analysis for seven spectrally matched ground motions. FVDs were installed at strategic locations, identified based on maximum ‘design basis earthquake’ elastic modal racking shear deformation demands and force (shear and moment) demands in three different options. The force, deformation and energy demands on structural components are compared for conventional design and different options of FVDs. The comparison with conventional design shows that FVDs are effective not only for reducing shear force demand along wall height, bending moment demand at mid-height and deformation demands by 10, 45 and 35%, respectively, but also significantly reduce the rotation and energy demands in the core wall by 60 and 450%, respectively.

A series of dynamic centrifuge tests were carried out at the geotechnical centrifuge facility of IFSTTAR in Nantes, to investigate the response of box-type tunnels embedded in dry sand under sinusoidal and seismic excitation, as affected by soil-tunnel relative flexibility and soil-structure interface rugosity. The system under investigation was analyzed by means of full dynamic time history analyses, implementing rigorous finite element models. The numerical models were calibrated on the basis of back analysis of tests, while the numerical predictions were compared with experimental data, in terms of soil and tunnel horizontal acceleration, soil shear strains and tunnel deformations. The validated numerical models were then employed to further investigate several aspects of the system seismic response. Results indicate a rocking deformation mode coupled with the well-known racking distortion of box-type tunnels under seismic shaking. The effect of the soil-tunnel interface characteristics and soil yielding on the racking deformation of the tunnel, the dynamic earth pressures and shear stresses around the tunnel, as well as on dynamic lining forces is also reported. Soil yielding leads to post-shaking, residual, dynamic earth pressures, shear stresses and lining forces, especially in the case of flexible tunnels, while interface characteristics affect the distributions of these response parameters around the perimeter of the tunnel section. The ability of simplified seismic design methods for tunnels to predict the response is finally discussed, by comparing their predictions with the recorded data and the numerical results.

Industrial storage racks are among the most important structures made from cold-formed steel sections. They are widely used due to the increasing need for rational space utilization in warehouses, and other facilities used to store goods. Pallet rack is a material handling, storage aid system designed to store materials on pallets. Although there are many varieties of pallet racking, all types allow for the storage of palletized materials in horizontal rows with multiple levels. Rack systems are widely used in warehouses where they are loaded with valuable goods. The cold-formed steel columns usually have open cross-sections and are thin walled, making them vulnerable to torsional-flexural buckling and local buckling. The loss of goods may be greater than the total cost of the rack on which the goods are stored, which can indirectly affect the owner. Therefore, understanding the stability of rack structures is very important. This paper deals with numerical linear and nonlinear buckling analysis of 2-D cold-formed steel simple cross-aisle storage rack frames. The main focus of the study is to ascertain the stability of 2-D frames of a pallet racking system. With this objective, a pallet racking system with cold-formed steel sections is simulated by three-dimensional models using shell elements in ABAQUS, a general purpose finite element analysis software. Linear and nonlinear buckling analyses are carried out on these frames. Results are obtained from finite element analysis of frames with 12 types of column sections. Spacer bars and channel stiffeners are used to improve the torsional strength of original open cross sections. Results show that spacer bars and channel stiffeners are very effective in enhancing the strength of cold-formed steel pallet rack structures.

The point fixed glass façade system is popular and considered a more elegant façade option compared to the framed glass façade system mainly for storefront, walkways and lobby areas in buildings. Point fixed glass façade system is fixed to the support structure using special bolt fittings and structural spider arms. Generally, the racking performance of these systems is not considered at the design stage in low to moderate seismic region and the system may be vulnerable if there is insufficient in-plane drift capacity compared with the demand imposed during earthquakes and wind actions. A unique full-scale in-plane racking laboratory test on a typical point fixed glass façade system was conducted and a maximum drift of 2.1% was measured before catastrophic failure. Non-linear finite element models were then developed and benchmarked against experimental results. The experimental results and finite element analyses indicated that a significant amount of the drift capacity was attributed to the rigid body translation in the façade system connections at the built-in oversize holes provided for construction tolerances. In this article, the laboratory test setup and the experimental results are summarised, and the finite element modelling methodology and non-linear analysis approach undertaken using ANSYS for the experimental test are discussed along with number of parametric studies.

When precast concrete infill panels are connected to steel frames at discrete locations, interaction at the structural interface is neither complete nor absent. The contribution of precast concrete infill panels to the lateral stiffness and strength of steel frames can be significant depending on the quality, quantity and location of the discrete interface connections. This paper presents preliminary experimental and finite element results of an investigation into the composite behaviour of a square steel frame with a precast concrete infill panel subject to lateral loading. The panel is connected at the corners to the ends of the top and bottom beams. The Frame-to-Panel-Connection, FPC4 between steel beam and concrete panel consists of two parts. A T-section with five achor bars welded to the top of the flange is cast in at the panel corner at a forty five degree angle. The triangularly shaped web of the T-section is reinforced against local buckling with a stiffener plate. The second part consists of a triangular gusset plate which is welded to the beam flange. Two bolts acting in shear connect the gusset plate to the web of the T-section. This way the connection can act in tension or compression. Experimental pull-out tests on individual connections allowed their load deflection characteristics to be established. A full scale experiment was performed on a one-storey one-bay 3 by 3 m infilled frame structure which was horizontally loaded at the top. With the characteristics of the frame-to-panel connections obtained from the experiments on individual connections, finite element analyses were performed on the infilled frame structures taking geometric and material non-linear behaviour of the structural components into account. The finite element model yields reasonably accurate results. This allows the model to be used for further parametric studies.

The mechanical behaviour of timber frame shear walls subjected to in-plane forces has been investigated through full-scale tests. Eleven monotonic and 11 cyclic tests were performed on full-scale shear walls, each 2·5 m high and 2·5 m long. Different variables were changed during the tests as follows. Different vertical loads were applied, different angle brackets and hold-downs were used and different sheathing panels were connected to the timber frame. Also, the influence of openings was investigated. Furthermore, two walls with non-structural finishing were tested in order to correlate the inter-storey drift with the level of damage. This paper (part 2) reports on a comparison between different test results, permitting evaluation of the influence of each variable on the stiffness and the resistance of the walls. Moreover, the theoretical formulae presented in a companion paper (part 1) were compared with the outcome of the tests, and good agreement was found. The racking resistance predicted by Eurocode 5 was also checked using the data obtained from the tests.

As revealed by the collapse of the Daikai Metro station during the 1995 Kobe earthquake, underground structures are not immune to seismic loading. Shanghai Metro operates 16 lines of 676 km length, comprising 413 underground stations. An additional 1000 km with 600 underground stations are planned for the next 20 years, calling for improved understanding of their seismic response. This paper studies the seismic performance of a typical 2-storey, 3-span Shanghai Metro station in soft soil, combining shaking table testing and numerical modelling. Notwithstanding scale effects, shaking table testing is performed to allow detailed simulation of the complex structural system of the station. The structure is modelled using granular concrete and galvanized steel wires to simulate the RC prototype. To remedy the problem of scale effects, synthetic model soil (a mixture of sand and sawdust) is used, along with similitude relations derived considering dynamic equilibrium. The properties of the synthetic model soil are adjusted to satisfy similitude; target stiffness and density are attained by adjusting the mixture proportions. To quantify the transferability of the results to prototype scale, the experiments are simulated with nonlinear finite elements (FE), modelling the synthetic model soil with a kinematic hardening constitutive model, calibrated against resonant column and direct shear tests. The FE model is shown to compare adequately well with the shaking table tests. The validated FE model is used to predict the seismic response of the prototype, thus allowing indirect transfer of the results from model to prototype scale. The model in prototype scale is calibrated for the real soil layers against in situ (down-hole) and laboratory (resonant column) tests. Moving from model to prototype scale, the racking deformation remains qualitatively similar. The racking drift is reduced by 50% going from model to prototype scale, which is partly due to scale effects, but also related to differences between the idealized soil of the experiments and the multiple soil layers encountered in reality. The maximum bending moment also reduces by 30% going from model to prototype scale. The base of the lower-storey columns is proven to be the most vulnerable section, as was the case for Daikai.

This paper discusses the strength and stability of cold-formed welded hollow sections with and without stiffeners, as well as four different cross-section shapes, in terms of the “Overall Interaction Concept” (OIC). The studied types of cross-section are employed in various fields of the construction sector, and particularly in racking systems, where weight minimization is a specifically emphasized design objective. The scope of the study consists of an extensive experimental campaign, coupled with a comprehensive series of numerical tests. The results shown were developed in the framework of the European (RFCS) research project HOLLOSSTAB. The discussion of the results in terms of the OIC approach highlights its potential as a general method for the cross-sectional design for hollow sections of various shape, loaded in various combinations of compression and bending.

This paper discusses the sliding behaviour of pallets in industrial racking systems under dynamic actions. For this purpose, a summary of the results of an extensive series of dynamic shake-table tests are presented; complete results of this extensive testing campaign may be found in a recently published book. Dynamic and seismic tests have been performed using three beam types with different surface finish materials, in both the Cross-Aisle (CA) and Down-Aisle (DA) directions. Lower and upper bound accelerations were determined from the uniaxial dynamic tests. Several phenomena related to deformations of the supporting beams (i.e. in- and out-of-plane bending) were found to affect the pallet behaviour, in both the CA and DA directions, with sliding occurring at very low acceleration levels. The same behaviour was observed during uniaxial earthquake tests. For biaxial seismic testing, lower bound acceleration in the CA direction was higher than in dynamic cyclic tests, whereas the opposite was observed in the DA direction.

This paper provides a quantitative assessment of the racking performance of partially anchored timber framed walls, based on experimental tests. A total of 17 timber framed wall specimens, constructed from a combination of materials under different load configurations, were tested. The experimental study was designed to examine the influence of a range of geometrical parameters, such as fastener size and spacings, wall length, arrangement of studs and horizontal members, as well as the effect of vertical loading on the racking strength and stiffness of the walls. The experimental results were then compared with results obtained from design rules, as given in the relevant European standards, to determine the racking performance of the walls, and are discussed in the paper.

In order to design energy-efficient timber-frame buildings with enlarged fixed glazing, mostly placed in the south-oriented external wall, it is of primary importance not only to take advantage of a high possible solar potential to heat the building, but also to assure a horizontal stability of such timber-glass structures. The paper presents the outcomes of a large experimental research on timber-glass wall elements where glass panes are directly bonded to the timber frame, which results in a load-bearing and visually interesting wall element suitable for lightweight timber structures. Three different types of adhesives (silicone, polyurethane and epoxy) were used with two different bonding line conditions to obtain an optimal type of connection which will be in praxis suitable for wall elements subjected to either monotonic or dynamic load impact. In the presented experimental research, strain measurements were supported by additional numerical FE analysis. Only such detailed studies and analyses could lead to the complete understanding of the specimen’s failure mechanism. The failure mechanism depends primarily on the type of adhesive and the type of bonded joints. These two parameters have a decisive impact on the element ductility and are important for further research. The analysis of the measured and calculated values confirmed the predictions that the stiffness and load-bearing capacity of timber-glass wall elements crucially depend on the interaction between the wooden frame and glass, which in turn is a function of the flexibility of the particular type of adhesive used.

Under seismic loading, underground station structures behave differently from above ground structures. Underground structures do not require designated energy dissipation system for seismic loads. These structures are traditionally designed with shear or racking deformation capacity to accommodate the movement of the soil caused by shear waves. The free-field shear deformation method may not be suitable for the design of shallowly buried station structures with complex structural configurations. Alternatively, a station structure can develop rocking mechanisms either as a whole rigid body or as a portion of the structure with plastic hinges. With a rocking mechanism, station structures can be tilted to accommodate lateral shear deformation from the soil. If required, plastic hinges can be implemented to develop rocking mechanism. Generally, rocking structures do not expect significant seismic loads from surrounding soils, although the mechanism may result in significant internal forces and localized soil bearing pressures. This method may produce a reliable and robust design of station structures.

Glass façade systems in buildings are subject to racking actions caused by inter storey drifts from earthquakes and wind action. The performance of façade systems is dependent on the amount of imposed drift and the interaction of the glass panels with the façade structural support frames. There are two major concerns related to the glass façade system performance during and immediately after a seismic event; hazards to people from falling glass and the cost associated with building down time and repair. It was observed that earthquake damage to glass façade systems resulting from in-plane racking actions is increasingly common and yet there has been limited research published in this field. The research completed to date has mainly focused on traditional framed glass façade systems; however, the racking performance of point fixed glass façade system (PFGFS) is likely to be quite different. Therefore, the aim of the research presented in this paper is to assess the in-plane racking performance of PFGFS which is a façade system gaining popularity worldwide. Two unique full scale in-plane racking laboratory tests on typical PFGFS with different types of connections were conducted and specific racking mechanisms were identified. Sophisticated non-linear finite element models (FE models) were developed and benchmarked against experimental results with excellent correlation. Further detailed FE analyses were conducted to evaluate the individual drift contributions of each racking mechanism such as rigid body translation of the glass panels at the oversize holes for construction tolerance, spider arm rotation and spider arm deformation. It was found that most of the drift capacity is attributed to the rigid body translation at the oversize holes. In this paper, the laboratory test setup and the experimental results are discussed together with the confirmatory FE analysis results to assess the in-plane racking performance of the PFGFS.

Glazed curtain walls are facade systems frequently chosen in modern architecture for mid and high-rise buildings. From recent earthquakes surveys it is observed the large occurrence of non-structural components failure, such as storefronts and curtain walls, which causes sensitive economic losses and represents an hazard for occupants and pedestrians safety. In the present study, the behavior of curtain wall stick systems under seismic actions has been investigated through experimental in-plane racking tests conducted at the laboratory of the Construction Technologies Institute (ITC) of the Italian National Research Council (CNR) on two full-scale aluminium/glass curtain wall test units. A finite element model has been calibrated according to experimental results in order to simulate the behavior of such components under seismic excitation. The numerical model investigates the influence of the interaction between glass panels and aluminium frame, the gasket friction and the stiffness degradation of aluminium-to-glass connections due to the high deformation level on the curtain walls behavior. This study aims to give a practical support to researchers and/or professionals who intend to numerically predict the lateral behavior of similar facade systems, so as to avoid or reduce the need of performing expensive experimental tests.

Palettenregalsysteme weisen unterschiedliche Merkmale bezuglich der verwendeten Profile und ihrer Verbindungen auf, wodurch sie sich von ublichen Stahlbauten unterscheiden. Sie gehoren nicht zu Gebauden, so dass ihr Erdbebennachweis nicht nach den Bestimmungen fur Hochbauten ausgefuhrt werden kann. In diesem Beitrag wird durch Anwendung nichtlinearer statischer Berechnungsverfahren das Verhalten solcher Systeme unter Erdbebenbeanspruchung untersucht. Dabei wird das nichtlineare Tragverhalten systemspezifischer Tragwerkskomponenten mit experimentellen und rechnerischen Untersuchungen bestimmt. So lassen sich Verhaltensfaktoren (q-Faktoren) individuell fur jedes Palettenregalsystem bestimmen. Ferner lasst sich ermitteln, wie ein System auf das Bemessungserdbeben reagiert bzw. inwieweit die angenommenen inelastischen Reserven ausgenutzt wurden, wie in neun Anwendungsbeispielen gezeigt wird. Seismic performance of steel pallet racking systems. Pallet racking systems have peculiar characteristics in respect to the member’s profiles and their joints and differ from the usual steel structures. They are not buildings so that their seismic design cannot be performed according to the relevant rules for buildings. This paper presents the seismic performance of pallet racks by means of non-linear static (pushover) analyses. The non-linear behavior of system specific components is determined by means of experimental and numerical investigations. This allows the determination of behavior factors (q-factors) for each individual system separately. In addition the performance of a specific system to the design earthquake may be determined as wellas how far the inelastic reserves have been exploited. The application of the method is shown by nine case studies.

Finger-joined lumber studs are considered equivalent to, and can be used interchangeably with, unjoined lumber of the same grade in residential construction in Canada. However, there have been concerns expressed by engineers and users that there is no data available on the mechanical performance of shearwalls built with finger-joined studs to support this equivalency. This study was intended to address this information gap. Two groups of finger-joined studs were fabricated using ‘No. 2 or better’ grade spruce-pine-fir (SPF) lumber and a heat resistant polyvinyl acetate (PVA) adhesive. One group had 2–3 joints per stud, while the second group had 5–6 joints per stud. A control group of unjoined ‘No. 2 or better’ grade SPF lumber was sampled as a reference for comparison between groups. The stud dimensions were 38 mm × 89 mm × 2.44 m. Sheathing used was oriented strand board (OSB) panels with dimensions of 1.22 m × 2.44 m × 12.5 mm. The stud frame was fastened using 12d common wire nails and the sheathing was fastened to the stud frame using 8d common wire nails. A total of 12 shearwall test specimens of dimensions 2.44 m × 2.44 m were fabricated and tested. Test results showed that there was no statistically significant difference in the mechanical performance in terms of peak racking load and stiffness between shearwalls containing finger-joined studs (up to 5–6 joints) and shearwalls containing unjointed studs. The failure mode for each test wall was a combined sheathing nail withdrawal and sheathing nail head pull through. This study provides confirmation that finger-joined studs made using the PVA adhesive in this study could be deemed to be equivalent to unjoined studs in fabrication of shearwalls.

A new method to assess the raking performance of Platform timber framed walls, is provided in this study: each component of the unit wall assembly is assumed as rigid, hence allowing to drastically reduce the overall number of DoFs involved within the model. The timber frame in particular, is modelled as a mechanism, having only two DoFs (regardless of the number of studs) corresponding to the horizontal and rotational displacements of the header beam. For a given imposed horizontal displacement Δ h , the corresponding racking load P ( Δ h ) is computed by numerical relaxation, allowing to consider a continuous function to represent the load-slip curves of the connections. A comparison of the numerical analysis against laboratory test results is provided, showing the method’s capability in predicting the raking strength of the wall, despite the assumed reduced number of DoFs.

In the UK, the design procedure for calculating the racking strength of timber-framed walls is based on the rules in Eurocode 5 and given in PD 6693-1. Currently, the PD method does not include a procedure for calculating racking strength using the results from wall panel racking tests to BS EN 594. Under the Building Regulations (England and Wales), BS 5268-6.1:1996, which was superseded by Eurocode 5, can still be used and this standard includes a calculation method using test results from BS EN 594:1996. As BS EN 594:2011 uses a revised test procedure, it has been found that the results are no longer compatible with the BS 5268-6.1 design procedure. This paper describes an extensive experimental programme investigating the compatibility and suitability of the test method in BS EN 594:2011 with the racking design method in BS 5268-6.1:1996. The test results have been analysed and compared, and appropriate recommendations are made.

Compared to bridges, underground structures are inappropriately regarded as less crucial components of road infrastructure in view of their supposedly low seismic vulnerability. The literature indicates, however, that shallow-buried rectangular structures, such as box culverts or rectangular tunnels, can be affected by shaking failure. To avoid the complexity of a fully non-linear soil–structure interaction analysis, a number of simplified methods have been proposed in recent years, which have gained popularity among designers. The aim of this paper is to investigate the applicability limits of such simplified analyses. The study compares the results obtained using simplified approaches with those emerging from non-linear static soil–structure interaction analyses, accounting for the following effects: the frictional behavior of the soil–structure interface, the geometry of the box structure, the overburden depth, the maximum PGA, and the increasing soil stiffness with increasing depth. The outcomes of the analysis indicate that shallow-buried rectangular structures are strongly affected by non-linear frictional effects at the soil–structure interface. The soil–structure interaction under seismic condition is shown to change smoothly from the condition of deep burial to the condition of “null overburden depth”. For a given aspect ratio, stiff, shallow-buried rectangular structures prove to be affected more deeply by sliding at the soil–structure interface than flexible structures and, for low aspect ratios, these structures may undergo a rigid rotation (rocking) that may even involve a partialization of the base foundation. For a reliable evaluation of member forces from racking distortions, rocking must be carefully taken into account.

A research group has recently been formed at the University of Salford with the general aim of investigating lightweight structures. The first task of the group is to look at the behaviour of perforated steel columns used for storage racking. The steel columns used in storage racking are made from perforated light gauge steel, with the perforations facilitating the connection of the storage racking beams. Recent work by Casafont et al. [1] has investigated the axial capacity of such members by a combination of testing and calculation, whereas another approach has been reported by Dinis et al. [2]. This paper describes the initial work of the group, investigating the possibility of assessing such capacity by using Eurocode 3 [3] equations to calculate the failure load of the column, using a critical buckling load that allows for the perforations in the column [4]. Critical buckling loads are calculated using both generalized beam theory and finite element analysis. The use of generalized beam theory is illustrated for problems of varying complexity, from a very simple uncoupled solution with one equation up to the final coupled finite difference eigenvalue solution. The paper concludes that it is currently possible to predict the capacity within a 15 % margin, and that further work could indeed improve this.

Structural insulated panel (SIP) wall systems have been used in residential and light commercial buildings for the past 60 years. Lack of sufficient published research results on racking load performance and understanding of the influence of fastener types on seismic response has been a deterrent in the widespread use of the wall system in seismically active areas. This paper summarizes the results of a full-scale racking load testing study in which a total of 17 2.4×2.4-m (8×8-ft) SIP wall panels were tested under monotonic and cyclic loading. Four 114-mm (4.5-in.) thick SIP specimens were tested under monotonic loading, while 13 114-mm (4.5-in.) thick SIP specimens were tested under the Consortium of Universities for Research in Earthquake Engineering loading protocol. Parameters such as fastener type, spline design, hold-down anchor location, and sheathing bearing were adjusted throughout the testing to determine their effects on the SIP’s performance. Performance parameters such as peak load a...

The stability of steel storage racks in the cross-aisle direction is typically ensured by cold-formed steel bolted upright frames. Sensitive to second-order effects, accurately determining the shear stiffness of these frames is essential for seismic design and for ensuring the stability of the rack, especially for high-bay racks and racks supporting the building enclosure, where the outer rack frames must withstand cross-aisle horizontal actions due to wind loading. The main international racking specifications adopt different approaches to determining the shear stiffness of cold-formed steel storage rack upright frames. The Rack Manufacturers Institute (RMI) specification conservatively uses Timoshenko and Gere's theory. The European Specification EN 15512 recommends testing, however it is not clear whether the shear stiffness obtained using the recommended test procedure is correct. The newly revised Australian Standard AS 4084 adopted the European approach but also introduced an alternative test method for determining the combined bending and shear stiffness of upright frames in the transverse direction. This paper reviews and analyses the factors influencing the shear deformation of cold-formed steel bolted upright frames and introduces the alternative test set-up adopted in the revised Australian Standard. 36 upright frames have been tested using the two test methods, and experimental results are presented, discussed and compared with finite element analysis results. Recommendations on how to use the test outcomes in design are also provided. Based on these recommendations, the paper shows that the two test methods are not equivalent and yield different results for the transverse shear stiffness of upright frames.

[EN] In the current paper, comparative analyses between three procedures of calculation have been developed, in order to obtain slab on grade thicknesses when the slabs are loaded with racking posts. For this case, the classical expression of Westergaard cannot be applied directly because of the influence of the remainder posts and their proximity. Firstly, the comparative analysis has been done by means of bibliographical design abacus; in the second place, the slab is discretized with finite elements resting above the soil modelled with soil reaction springs; and in third place, a three dimensional solid finite element model represents the base and subgrade set. In the paper some innovative issues regarding the thickness performance and the grade slab interaction are developed. Finally, a series of graphical results are obtained allowing for the pre-design., [ES] En el presente artículo se realiza un estudio comparativo entre tres procedimientos de cálculo para obtener espesores en soleras de hormigón ligeramente armadas por retracción, con cargas debidas a estanterías. Las fórmulas para cargas aisladas de Westergaard no tienen para este caso una aplicación directa debido a la influencia del resto de soportes y su cercanía. El estudio comparativo se realiza en primer lugar mediante nomogramas de cálculo de la bibliografía; en segundo lugar, la solera se discretiza con elementos finitos y apoya sobre el terreno modelizado con coeficiente de balasto, y en tercer lugar, mediante elementos finitos tridimensionales sólidos que representan la base y la explanada, desarrollándose aspectos novedosos en el tratamiento del conjunto solera-terreno tanto en sus expresiones como en su interacción. Asimismo, se obtienen una serie de gráficas que permiten realizar predimensionados.

This paper presents an experimental investigation of the racking performance of light-frame wood shear walls to evaluate the effect of Type X gypsum wall board (GWB). Twelve shear walls she...

Drive-in storage racks, made of cold-formed steel, are the main racking system used in industry for storing goods. The storage space utilization of drive-in racks is high at the price of the weak downaisle stability. This paper presents a general analysis of the lateral stiffness of drive-in racks in the downaisle direction. A total of 24 static tests of drive-in rack systems have been conducted under single-point horizontal force. The effects of some constructional details, such as bracing configuration, cargo pallets, and the number of bays, are considered. The experimental results indicate that either top plan bracing or back-spine bracing can change the load transfer through rack structures and increase the lateral stiffness of racks. By acting as the horizontal bracings of adjacent columns and reinforcing the rotational stiffness of column bases, the stored pallets are also the beneficial factor for improving the lateral stiffness of racks. According to the special structural characteristic o...

In order to investigate the sliding behavior of pallets stored on steel racking systems, a large number of sliding tests under both static and dynamic conditions were performed within the EU-RFCS Research Project “SEISRACKS: Storage Racks in Seismic Areas”. In this paper, the results obtained for the assessment of the Static Friction Factor between pallet and beams are described and commented upon.

Pallet racking systems, made of thin-walled cold formed steel profiles, are commonly used to store valuable goods and products in the logistics industry. In service conditions, longitudinal (down-aisle) stability of the racks is provided by the flexural stiffness of the demountable beam-upright column connections and base joints. Rack designers usually prefer to avoid bracings for a full accessibility of shelves from both aisles. However, under seismic conditions, typical rack connections cannot often provide sufficient flexural performance in terms of stiffness and strength, which deems necessary to introduce spine (longitudinal) bracings in the down-aisle direction. Yet the racks can only be braced at one of their two longitudinal planes to allow pallet loading from the aisle, which results in an asymmetric horizontal bearing configuration. This combined with their perforated upright columns, and non-standard beam-upright and base connections make it even more difficult to estimate their complex global seismic performance. Therefore, full scale experimental investigations are strongly needed in order to understand and quantify the global performance of the braced storage racks, and improve their design for seismic actions. This paper presents the experimental results of the Europe's largest full-scale push-over testing program that has been carried out on racking systems. In particular, experimental global capacity curves of 6 fully-loaded pallet racking specimens with spine bracings, provided by 5 different international rack producers, are presented, discussing the key factors influencing the racks’ response, as well as the failure mechanisms of the different rack typologies. Furthermore, behaviour factor (q) values of each specimen are derived from re-analysis of test results. Vulnerability of braced racks to bracing connection failure is demonstrated, highlighting its causes. Design indications are provided in order to guarantee a globally homogenous ductility under seismic actions.

Steel storage racks are typically made of thin-walled cold formed steel profiles, which prove to be the most versatile, economic and sustainable elements for industrial rack construction. Their lightweight structural systems are usually designed to resist heavy load units, reaching considerable heights. However, the global behavior of storage racks under seismic actions is much less predictable than the behavior of steel buildings made of standard steel profiles and connections, mainly due to the perforations in their thin walled upright columns, and their semi-rigid beam-column and base plate joints. Full scale experimental investigations are greatly needed in order to understand and quantify the global performance of storage racks, and improve their design for seismic actions. For the first time in Europe, thanks to the funding provided by Research Fund for Coal and Steel (RFCS), an extensive full-scale push-over testing program has been carried out on 8 fully-loaded pallet racking specimens (4 unbraced and 4 braced racks), provided by 4 different international rack producers. This paper presents the experimental results of full scale push-over tests performed in the down-aisle (longitudinal) direction on fully-loaded unbraced specimens. In particular, experimental global capacity curves of the tested specimens are presented, discussing the key factors influencing the racks’ response, as well as the failure mechanisms of the different rack typologies. Furthermore, the behavior factor (q) values of each specimen are derived from re-analysis of the test results. Vulnerability of unbraced racks to soft-storey mechanism is demonstrated, highlighting its causes. Design guidelines are provided in order to guarantee a globally homogenous ductility under seismic actions, along with the new safety requirements for the design of the floor connections of unbraced racks.

The performance of portal frame walls was studied using a finite-element model verified with results from tests of full-size portal frame walls. Parameters such as wall height, metal strap type and location, doubling of the bottom plate, sheathing placement, and nailing pattern were investigated. Results indicate that in all cases, lateral load capacity and stiffness are greatly reduced with the increase of wall height. Considering the effect of different metal strap types and locations, the tensile strength of metal straps has the greatest impact on the lateral load capacity and stiffness. Walls with metal straps placed directly on the framing members outperform walls with metal straps placed over the sheathing. For walls with a double bottom plate and two rows of nails fastening the bottom plate, the stiffness and lateral load capacity are slightly increased compared with walls with a single bottom plate. For walls with unblocked sheathing at midheight, the lateral load capacity is the same as i...