Lateral Loading Conditions Research Articles

Study of multi-cell thin-walled tube with various configuration under lateral loading

Thin-walled structure is one of the common structures that is widely used as an energy absorber due to inexpensive, high availability and lightweight. Moreover, the multi-cell structure is known as a useful method to elevate the effectiveness of thin-walled structures in crashworthiness. Energy absorber performance of multi-cell thin-walled tube structure is known to be greater than the single thin-walled tube. This is due to the limitation of plastic hinge zones of single tube during lateral loading condition. This paper presents the effect of multi-cell configuration on energy absorption responses under lateral loading condition. Experiment and numerical approach were used in this research. The validation of finite element model (FEM) was conducted by comparing the load-displacement responses and deformation mode of a quasi-static compression test. Multi-cell configuration study was performed to identify the energy absorption performance of multi-cell thin-walled tube with different arrangements. The results reveal that an increasing number of cells will increase the energy absorption capacity of multi-cell structure. The additional number of tube cells contribute to the increases of the contact joint between each tube consequently this generate additional permanent plastic-hinges.

Efficacy of beam-type finite elements in the evaluation of lateral stiffness of 16×16 fuel assemblies by strengthening mechanisms

The structural strength of fuel assemblies in the nuclear reactor core during the energy generation process is an important characteristic to consider, due to the need to withstand lateral static and dynamic loads resulting from external forces, an outcome from postulated accidents, such as an earthquake. This requirement demands a sustained cooling activity for the fuel assembly by keeping a proper geometry, i.e., avoiding structure deformation. This can be achieved mainly by an adequate mechanical design for the spacer grids since this component would be the first to get in contact with the ordered mechanical structure (neighboring fuel assembly or the core baffle). In this way, the understanding of nuclear fuel mechanical behavior becomes essential, even to any subsequent geometrical modifications to optimize the performance of the fuel assembly. The main goal of the present study was to analyze the structural strength behavior of this component in order to provide consistent predictions of 16x16-type fuel assembly lateral stiffness when submitted to external forces. Thus, a beam-based finite element model was proposed to predict this fuel behavior, in which the hold-down spring force, spacer grid to guide thimble connection stiffness, and spacer grid stiffness were varied, in order to get more information about the fuel assembly rigidity sensitivity and verify if the proposed strengthening mechanisms for the structure are effective. Rigidity predictions of nuclear fuels allow verification of adequate design regarding functionality and reliability. Finally, the proposed finite element model was validated in terms of fuel assembly deflection by comparison with experimental results.

Study on Retrofitted Masonry Elements under Shear Using Digital Image Correlation.

Architectural heritage is usually built with masonry structures, which present problems under lateral in-plane loading conditions, such as wind pressure or earthquakes. In order to improve the shear behavior of masonry, the use of a fabric-reinforced cementitious matrix (FRCM) has become an interesting solution because of its synergy of mechanical properties and compatibility with masonry substrates. For a proper structural evaluation, the mechanical behavior of reinforced masonry and the FRCM itself needs to be characterized. Hence, a numerical model to evaluate the FRCM reinforcement requires some mechanical parameters that may be difficult to obtain. In this sense, the shear behavior of masonry can be evaluated by means of diagonal tension tests on small specimens (71 × 71 cm). In this work, a digital image correlation (DIC) monitoring system was used to control displacements and cracking patterns of masonry specimens under shear stress (induced by diagonal tension with FRCM layers) applied to one or two sides. In addition, the mechanical behavior of FRCM coupons under uniaxial tensile tests was also registered with DIC. The displacement measurements obtained by DIC were validated with the measurements registered with LVDT. Unlike LVDT-based techniques, DIC monitoring allowed us to measure deformations in masonry during the full test, detecting crack initiation even before it was visible to the eye.

The Behavior of Plugged Pipe Piles Strengthened with Biaxial Carbon-Fiber under the Effect of Lateral Loads

This paper presents an experimental study to investigate the behavior of plugged pipe pile strengthened with biaxial carbon fiber under the effect of lateral loads in sand. The change of plug length and incremental filling ratio of pipe pile under static lateral load is considered. The model of piles is embedded in dense sand with different slenderness ratios of pile. In addition, different ratios of confining length of biaxial carbon fiber are used. The results indicated that the ultimate lateral resistance of plugged pipe pile increases with increase of the confining length of carbon fiber.

EVALUASI KINERJA STRUKTUR BANGUNAN MENGGUNAKAN PUSHOVER ANALYSIS DENGAN METODE ATC-40 DAN FEMA 356

Pushover analysis is a non-linear static analysis to determine the collapse behavior of a building or structure. The analysis is carried out by giving a static lateral load pattern to the structure, which is then gradually increased by a multiplier until a buliding movement target is reached. This final assignment research was conducted to determine the performance point based on ATC-40, to determine the performance level based on ATC-40, and to determine the performance level based on FEMA 356. The research method used the response spectrum with the SAP2000 v14 program. The result of the performance point in building with the values of Sa = 0,737, and Sd = 0,200 for the push X, while the values of push Y Sa = 0,680, and Sd = 0,225. The calculation of ATC-40 in building shows the value of the drift ratio in the X direction 0,01165 and the drift ratio Y direction 0,0127 at the level of performance Immediate Occupancy (IO). The result of FEMA 356 calculation in building shows the value of the lateral displacement target structure of the X direction structure = 0,00437 (0,437 %), and the value of the lateral displacement target of the Y direction structure = 0,006 (0,6 %) and at the level of performance Immediate Occupancy (IO). Then it could be concluded that The Dental & Mouth Hospital of UGM Prof. Soedomo, was at the level of performance Immediate Occupancy (IO), meaning that the building was still safe and could be reused after the earthquake and don’t occured serious demage.

Distributed Optical Fiber-Based Approach for Soil-Structure Interaction.

Scour is a hydraulic risk threatening the stability of bridges in fluvial and coastal areas. Therefore, developing permanent and real-time monitoring techniques is crucial. Recent advances in strain measurements using fiber optic sensors allow new opportunities for scour monitoring. In this study, the innovative optical frequency domain reflectometry (OFDR) was used to evaluate the effect of scour by performing distributed strain measurements along a rod under static lateral loads. An analytical analysis based on the Winkler model of the soil was carefully established and used to evaluate the accuracy of the fiber optic sensors and helped interpret the measurements results. Dynamic tests were also performed and results from static and dynamic tests were compared using an equivalent cantilever model.

Calculative Width of Pile Foundation on Slope Based on Particle Image Velocimetry (PIV)

The calculative width directly affecting the horizontal bearing capacity of the pile is an important parameter of the horizontal loaded pile foundation and its effective value will change with the variation of slope angle. In order to research the effect of slope on calculative width, 4 groups of model test under static lateral loading with different slope angles were carried out indoor. Based on the PIV system, the horizontal diffusion angle was obtained by the quantitative analysis of the vectorial displacement field of soil around the pile. The calculative width of pile under 4 slopes was then calculated based on the Horizontal Diffusion Principle. Compared with numerical simulation and full‐scale test, calculative width based on Horizontal Diffusion Principle is greater than that based on the code of China (JGJ94‐2008) and it decreases by about 3.3 m by every 10° increase of slope. After correcting the calculative width based on Horizontal Diffusion Principle, m‐value that can characterize the horizontal resistance of the pile is greater than that based on the code of China (JGJ94‐2008); the average difference of two m‐values is about 75 MN/m4. Slope has a strong weakening effect on m‐value. These conclusions provide a certain reference for the selection of calculative width in engineering.

A Case Study on the Selection of Optimum Loop Units for the Deployable Arch Structures Exposed to Lateral and Non-uniform Gravity Loads

Radially deployable arches may be created by using various types of units. However, for any deployable structure to be constructed in real life, it should satisfy the structural regulations and codes. Despite various advantages from architectural perspective, deployable structures are weak to satisfy the operational code limits when compared to trusses with similar height and span. Therefore, weight minimization is very important to reduce the dead loads of the structure which facilitates the code-conformance of the structure. The optimization of the deployable structures requires an initial selection of the loop types to define the structure parametrically. An initial selection strategy depending on the loads on the structure is important to increase the efficiency of optimization process. Under uniform gravity loads, optimum arrangement for each unit type converges to a similar point. However, in the real world, the loads on the arches are not always uniform and the structure is exposed to non-uniform loadings such as point loads or lateral loads. This work focuses on the performance of various arches with different unit types under lateral and non-uniform vertical loads. Different lateral load and non-uniform gravity loading scenarios are created. For each scenario, the arches with different units are analyzed. In all cases, clear span and height are kept as same. The performance of an arch with a specific unit type for a given load is measured with a score that includes the deformations and the weight of the structure. All the members are assumed to be circular hollow sections with variable diameter and thickness to have a meaningful weight comparison between structures. This work intends to define an initial selection guide for deployable arches under typical non-uniform and lateral loading conditions.

Cyclic behavior of the R/C frames with reinforced masonry infills

This study focuses on the experimental works to define the behavior of the reinforced concrete (R/C) frame model with the strengthening of the brick masonry infill by using the embedded reinforcement bars subjected to lateral reversed cyclic loads. A previous study by applying the lateral monotonic static loads showed that the embedded reinforcement bars increased the lateral capacity of the R/C frame and also delayed the failure of the brick masonry infill and R/C frame structure as well. However, in order to define its seismic capacity, a lateral reversed cyclic loading is required. The experimental works in this study were conducted by preparing and testing the 1/4 scaled-down R/C frame specimens represented the first story of the middle multi-story commonly constructed in the earthquake-prone area such as West Sumatera, Indonesia. The R/C frame specimens were two R/C frames with brick masonry infills where one of them strengthened by the embedded reinforced bars. All specimens were tested for applying the lateral reversed cyclic loads. The applied lateral load, the lateral displacement, the progressive cracks, and the failure mode of the specimens were observed and recorded during experimental works. As it was expected, the presence of the embedded reinforced bars in the brick masonry infills increases the seismic capacity and stiffness of the R/C specimens and also delayed the failure of the specimens. The experimental results in this study imply the simple strengthening method for the brick masonry infills.

Seismic Assessment of Asymmetric Single-Story RC Buildings by Modified Pushover Analysis Using the “Capable Near Collapse Centre of Stiffness”: Validation of the Method

ABSTRACT A modification procedure on the standard pushover analysis for single-story asymmetric RC buildings, based on the “Capable Near Collapse Principal Reference System”, has been proposed recently. According to this procedure, the lateral static floor loading is applied eccentrically to the mass centre, using inelastic dynamic eccentricities plus any accidental ones. In this work, variations of a single-story building, about the static eccentricity and the torsional sensitivity, are examined, to verify this new pushover procedure comparing with the results of N-LRHA. The results of this parametric investigation show that the proposed procedure can safely predict the building’s stiff and flexible-side displacements.

A Numerical Analysis to Solve a Geotechnical Problem of a Concrete Pile Subjected to a Static Lateral Load

This work is devoted to a numerical analysis of concrete pile subjected to a static load. As part of the development of methods and procedures to account for the effect of loadings on pile response, a numerical modeling using finite difference codes for 3D analysis has been performed. This paper presents the results of numerical computation in terms of accumulation of displacement at the head of pile and evolution of the lateral friction along the pile by exploring P-Y curves. By using these numerical results it has been possible to solve the geotechnical problem of determining the soil reaction coefficient. This study shows that the reaction coefficient of soil varies with depth. The solutions are based on soil-structure interaction modeling. The good agreement between theoretical and numerical results confirms the validity of the proposed solution.

Model Tests on the Frequency Responses of Offshore Monopiles

Monopiles are widely used to support offshore wind turbines as a result of the extensive development of offshore wind energy in coastal areas of China. An offshore wind turbine is a typical high-rise structure sensitive to dynamic loads in ocean environment such as winds, water waves, currents and seismic waves. Most of the existing researches focus on elastic vibration analysis, bearing capacity or cyclic degradation problems. There’re very few studies on vibration of monopiles, especially considering the influence of static loads with different amplitudes, directions, and loading-unloading-reloading processes. In this paper, laboratory-scale 1 g model tests for a monopile in dry sands were carried out to investigate the frequency responses of the monopile under different loading conditions. The bearing capacities of the model monopile were obtained as references, and dynamic loads and static loads with different amplitudes were then applied to the monopile. It was found that (1) the first resonant frequency of the monopile decreases with the increase of dynamic load amplitudes; (2) the first resonant frequency of the monopile steadily increases under the lateral static load and loading-unloading-reloading processes; (3) the frequency responses of the monopile with static loads in different directions are also quite different; (4) damping of the monopile is influenced by the load amplitudes, load frequencies, load directions and soil conditions. Besides, all the tests were conducted in both loose sand and dense sand, and the results are almost consistent in general but more obvious in the dense sand case.

Dynamic performance of bracket complexes used in traditional timber structures in Japan.

A bracket complex is a type of bearing system located on the top of a column and transmits the vertical load of the roof to the column. Bracket complexes are often used in Buddhist temples and Shinto shrines constructed using traditional timber structure. The bracket complex, being a combination of timber blocks and beam like elements, is said to have a positive effect on the seismic performance of traditional timber structures. However, this hypothesis has not been theoretically or quantitatively proven. The aim of the present paper is to clarify the dynamic performance of the bracket complex. The investigations of the present study were performed through experiments and analysis. Shaking table tests were conducted on four different types of bracket complexes. The stiffness, natural frequency, and load-displacement relationships were determined. The results were compared with those obtained by static lateral loading tests on the same specimen by the authors in previous studies. Earthquake response analyses were carried out by applying a structural model proposed by the authors based on the results of static lateral loading tests. The results of the analysis and shaking table tests are compared, and the validity of the proposed structural model is discussed.

Evaluation of the bonding and fatigue properties of an innovative rapid repair structure for concrete pavement

Deterioration and damage of pavements require rapid and durable full-depth repair. This study proposes an innovative rapid repair structure for the incorporation of precast slabs, graded gravel bases, and grouting technology in concrete pavements. Two representative grouting materials and two types of graded gravel bases with different particle size compositions were selected to construct four types of rapid repair structures. Static stepwise loading, fatigue loading, and lateral loading tests were conducted to evaluate both the effectiveness and feasibility of the rapid repair structures by measuring deformation, strain, and pressure as well as by examining the failure modes of the repair structures. The results indicated that the high strength grouting material contributes to the mechanical properties and bonding performance of the repair structure. Moreover, a well-compacted base is critical for the deformation uniformity of the repair structures and a graded gravel base with large particle size provides firm support, which is conducive to the infiltration of grouting material. The rapid repair structure proposed in this work not only reduces the time and cost required to re-open traffic, but also meets the requirements of a semi-permanent repair of concrete pavement. However, a full-scale investigation needs to be conducted to assess the mechanical properties for rapid repair structure.

Experimental and numerical study of OSB sheathed-LVL stud wall with stapled connections

This paper presents the results of an experimental and a numerical study on the OSB-LVL joints and light OSB sheathed-LVL stud walls. The joints and the walls were comprised of Laminated Veneer Lumber (LVL) studs and/or joists with 6 mm thick oriented strand board (OSB) sheathings stapled on both sides. First, monotonic static and cyclic tests were performed on the stapled OSB-LVL joints to study influence of the thin OSB panels, length of the staples and their edge distance on the failure mode, loading capacity and ductility of the OSB-LVL joints. Then, three full-scale OSB sheathed-LVL stud walls with pull-down rods were tested under monotonic static gravity and lateral loads and cyclic lateral loads to evaluate the failure load, ductility and energy dissipation capacity of the walls. The well-known CASHEW load-slip model was calibrated against the results of stapled OSB-LVL joints and the calibrated model was used in conjunction with a simple mechanistic model to predict the cyclic response of the light LVL stud walls with OSB sheathing. The wall behaviour under vertical and lateral loads were also simulated with a 3D nonlinear finite element (FE) model to further demonstrate advantages of the simplified models over advanced nonlinear FE models.

A coupled elasto-plastic damage model for fine-grained sandstone under triaxial compression and lateral extension loading conditions

A series of triaxial compression tests under confining pressures of 0, 3, 5, 10, 15 and 20 MPa and lateral extension tests under initial confining pressures of 10, 15 and 20 MPa are conducted. Compared to the test results under loading and unloading conditions, lateral deformation is more sensitive than the axial deformation under unloading process. According to the characteristic of volume strain, the stress–strain curves can be divided into five phases: initial nonlinear compaction, linear elastic, stable crack growth, unstable crack growth and post-peak stage. The experimental results show that dominant failure mode of both tests is shear failure. The failure mode becomes more complex at the confining pressure of 20 MPa in the lateral extension test, consisting of shear and tensile failures. Based on experimental results, a coupled elasto-plastic damage model is proposed using a nonlinear yield function in the p–q plane, using a non-associated plastic potential function in the irreversible thermodynamic framework. The isotropic damage evolution model is formulated with plastic coupling. The numerical simulation results using the coupled model agree well with the experimental data of the fine-grained sandstone, indicating that this model can describe the main mechanical behaviours of the rock under complex loading conditions.

Field experiments on laterally loaded piles for an offshore wind farm

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.

Soil–Structure Interaction of Pile in a Sloping Ground Under Different Loading Conditions

This paper presents the study of single pile in the sloping ground under different static lateral loading conditions in which the pile is subjected to forward and reverse loading at ground level and slope level. Laboratory experiments are conducted in a test tank with cohesive soil by embedding a semi-infinite pile. The behaviour of the pile is studied by considering three different slopes (1V:3H, 1V:2.5H and 1V:2H) with varying positioning of pile in-terms of relative stiffness factor (R). Relative stiffness is found by conducting lateral load test in horizontal ground condition for the same soil properties. Lateral load corresponding to 5 mm displacement is taken as the ultimate lateral load. The deformation and bending characteristics of the pile are observed for different conditions and compared with pile loaded at the levelled ground. Numerical studies are performed to validate the test results and to assess the effect of water table on pile-slope behaviour. Parameters such as optimum distance from slope crest towards the embankment where the effect of slope becomes void are also studied.

Determining fragility of urban low-to-mid rise masonry infilled building

In seismic analysis of building, infill wall is usually modelled as non-structural elements and, hence, are not taken into account in analytical models. In general, engineers and scientists model these widely used structural system of masonry infilled reinforced concrete frame by considering the infill wall as load applied to the open confining frame. The presence of masonry infills, however, may significantly alter both the stiffness and the strength of the overall structural frame system. This present study aims to evaluate seismic performance of this type of building by developing fragility functions of the structure. Masonry wall was modelled as diagonal strut within the concrete frame. The masonry constituents and its composite properties were determined for the model. Then, the structure was subjected to incremental static lateral loading while adaptive pushover analysis was utilized to predict the response of the structure. As the damage states were defined from the spectral capacity curves, the fragility functions were developed for the structure. Effect of masonry wall included in the analysis was then compared to the results of open frame. The result of the eigen value analysis shows, the period for modelling a structure with an infill wall is smaller compared to modelling a structure without infill wall (open frame). This shows that the existence of infill wall elements in modelling increases the value of structural stiffness so that it reduces the period of the structure. Whereas, the results of the fragility curve in both structural modelling show that at some level of damage, the probability of damage for modelling structures with infill walls is smaller when compared to open frame. Realistic and rational results is presented in this work which show that modelling masonry wall with compression strut is beneficial.

Static lateral load capacity of extruded wood-plastic composite-to-metal single-bolt connections, considering failure at the ends

The effect of the end distance was studied relative to the static ultimate lateral load capacity of a single-shear unconstrained wood-plastic-composite-to-metal single-bolt connection (SUWSC). Equations estimated the static ultimate lateral loads of the SUWSCs that failed during the end tear-out, splitting, and yield modes and were obtained using stress concentration factor regression- and mechanics-based approaches. The experimental results showed that the stress concentration factor was a linear function of the end-distance to bolt-diameter ratio for the SUWSCs that failed during end tear-out and splitting modes. The static ultimate lateral loads of the SUWSCs that failed during the yield modes were estimated using a mechanics-based equation. The minimum end distance for the SUWSCs that failed without end fracture (i.e., only with yield mode) was 25.4 mm, which was four times larger than the bolt diameter.