Horizontal Loading Tests Research Articles

Pseudo-static experimental study on insulated sandwich concrete wall with embedded columns

Insulated sandwich concrete wall with embedded columns (ISCW-EC) is proposed in this paper. For ISCW-EC, the embedded column is cold-formed steel rectangular tube and horizontal distributed reinforcement is used in concrete layer. To evaluate the shear strength and seismic performance of ISCW-EC and to study the effect of the horizontal reinforcement spacing, low-frequency horizontal cyclic load tests were performed on four full-scale specimens. The test results show that the failure pattern of ISCW-EC is a combination of local buckling at the bottom of the embedded column and concrete crushing at corners. The bending-shear failure dominated by bending occurs in regular walls, while the shear failure occurs in L-shaped walls. The results also show if the spacing of horizontal distributed reinforcement is too small, a brittle failure occurs. The shear capacity, ductility and energy dissipation capacity are significantly improved with larger horizontal reinforcement spacing. In addition, ISCW-EC is compared with a sandwich wall without embedded columns, the results show that the embedded columns significantly improve the shear capacity and ductility of ISCW.

Experimental study on the residual seismic resistance of ultra high performance cementitious composite filled steel tube (UHPCC-FST) after contact explosion

Abstract This paper aims to ex perimentally study the residual seismic resistance (RSR) of Ultra high performance cementitious composite filled steel tube (UHPCC-FST) specimen after contact explosion. Firstly, six 1/4 scaled circular UHPCC-FST were fabricated with the column height, outer diameter and core concrete compressive strength being 2000 mm, 203 mm and 131.5 MPa, respectively. Then, four of which were tested under contact explosion, in which the TNT charge weights were 1–3 kg and the height of bursts are all 250 mm. Furthermore, the RSR of both four post-blast UHPCC-FST columns and two intact control specimens were examined through the low-frequency horizontal cyclic loading test, in which two perpendicular loading directions were considered. It indicates that: (i) UHPCC-FST column suffered the localized cratering damage beneath the explosive, and the damage level became more severe with increasing the TNT charge weight; (ii) all the specimens endured the bending failure under the cyclic loadings, which occurred near the column bottom and cratering position for intact and post-blast specimens, respectively; (iii) RSR of the post-blast column deteriorated more obviously for the cyclic loading direction being perpendicular to the cratering face compared to that being parallel to the cratering face. Finally, based on the quantitative degradation of the seismic resistance, stiffness and energy consumption of the present UHPCC-FST specimens, a composite damage index was proposed to evaluate the RSR of the post-blast column after contact explosion. The present work could provide helpful references in the damage assessment and retrofitting of the post-blast column under potential contact explosions in the seismic zone.

The influence of laying patterns on the behaviour of historic stone pavements subjected to horizontal loads

Stone pavements are of great importance both for their historical and cultural value and for the most modern ecological and aesthetic requirements appreciated thanks to the use of natural materials of different colours, shapes and sizes which are laid in different patterns. Since stone block pavements are made up of individual elements with irregular side surfaces that interact with each other, an important parameter that must be considered in the design is their structural strength to horizontal stresses mainly due to braking, turning and accelerating vehicles. In this study horizontal load tests were performed on stone pavements built in a wide laboratory test chamber to analyse the load-shifting behaviour for different geometric arrangements. The displacements distribution of the elements was determined by a photogrammetric analysis. The tests have shown that the behaviour of the stone pavements in the horizontal plane is significantly influenced by the laying pattern, both in terms of translations and interaction between the elements.

Three-dimensional finite element analysis of laterally loaded bridge caisson foundations in gravelly soil

In this paper, we propose a three-dimensional finite element model that can simulate the caisson foundation behavior in gravelly soil. The soil model adopts a combination of the porous elastic model and the modified Drucker–Prager/Cap model for simulating the gravelly soil. For avoiding problems in laboratory testing on gravel specimens, a practical approach is proposed to determine and calibrate the parameters of the soil model using results of field geotechnical tests, such as a shear wave velocity profile, strength parameters of direct shear tests, and pressure–displacement curves of vertical and horizontal plate loading tests. The proposed finite element model was applied to simulate in situ lateral load tests on bridge caisson foundations in gravelly soil. Using the calibrated soil model, responses of caisson displacement, caisson head rotation, and soil displacement analyzed were observed to be in agreement with the measured responses. Caisson and surrounding soil responses were also investigated in detail.

Post-fire seismic performance of SRC beam to SRC column frames

This paper investigates the post-fire seismic performance of steel reinforced concrete (SRC) beam to SRC column frames. Five SRC column to SRC beam planar frame specimens were tested in a program including a loaded fire test and a following horizontal cyclic loading test. Test parameters included heating time and column load ratio. The temperature development, deformation, post-fire hysteretic and skeleton curves, stiffness, ductility and damping coefficient of SRC frames are recorded, calculated and analyzed. The measured post-fire hysteretic curves indicates that the SRC frames exhibit very good energy dissipation capacity after fire exposure. The horizontal load capacity and viscous damping coefficient of SRC frames increase with the increase of column load ratio. However, column load ratio has an adverse influence on ductility as anticipated at normal temperature. One SRC frame specimen failed during the cooling phase, which demonstrates the importance of considering the cooling phase during the fire safety design.

Role of punching shear reinforcement in the seismic performance of flat slab frames

Horizontal cyclic loading tests of flat slab–column specimens indicate that a considerable enhancement of the drift capacity can be achieved by introducing punching shear reinforcement. However, seismic design codes either do not recommend or do not cover buildings in which flat slabs are part of the primary lateral load resisting system. Nonetheless, flat slabs are popular, even in earthquake-prone areas. The purpose of this paper is to contribute towards a better understanding of the benefits and limitations of using punching shear reinforcement in the seismic performance of such structures. To this end, nonlinear static analyses and a set of fragility functions are derived for two reinforced concrete three story frame models. To minimize modelling uncertainties, the numerical models are calibrated based on two laboratory specimens (one without punching shear reinforcement and the other with headed studs) tested under reversed horizontal cyclic loading. The results show that the performance of the frames can be improved by introducing punching shear reinforcement. However, it is shown that the inherent flexibility of slab–column connections under lateral loading remains a limiting factor even when punching shear reinforcement is provided.

Seismic performance of RC columns with full resistance spot welding stirrups

This paper aims to investigate the seismic performance of RC short columns and long columns with welding stirrups. Through the low-cyclic horizontal loading test of specimens, the seismic performance indexes such as failure modes, hysteretic curve, skeleton curve, ductility, energy dissipation capacity, stiffness degradation and strength degradation were emphatically analyzed. Furthermore, the effects of shear span ratio, stirrups ratio and axial compression ratio on the performance of specimens were studied. The results showed that the seismic performance of the RC short columns with welding stirrups were basically the same as that of the RC short columns with traditional stirrups, but the seismic performance of RC long columns with welding stirrups was better than that of RC long columns with traditional stirrups. The seismic performance of RC short columns and long columns with welding stirrups could be improved by increasing stirrup ratio and shear span ratio and reducing axial pressure ratio. Moreover, the welding stirrup have the advantages of steel saving, industrialization and standardization production, convenient construction, and reducing time, which indicated that the welding stirrups could be applied in practical engineering.

H-M Bearing Capacity of Cone-Shaped Foundation for Onshore Wind Turbine under Monotonic Horizontal Loading

In this paper, monotonic horizontal loading tests were carried out to study the bearing capacity of the cone-shaped foundation in marine fine sand. With load-controlled methods, the horizontal load was applied to the rod of cone-shaped foundation at loading eccentricity ratios of 5.0, 6.0, and 7.0. In addition, theoretical analysis was used to investigate the horizontal ultimate bearing capacity, and finite element analysis was also used in this paper to investigate the influence factors of the bearing capacity of cone-shaped foundation. Based on the theoretical analysis, the formula for horizontal ultimate bearing capacity was deduced. Test results show that, at the same loading eccentricity, cone-shaped foundation can provide higher H-M bearing capacity as well as lower lateral deflection compared to regular circular foundation for wind turbines. In addition, the deflection-hardening behavior of load-deflection curve for cone-shaped foundation is also observed. Numerical analysis results show that the H-M bearing capacity of the cone-shaped foundation increases with increasing aspect ratio and buried depth, however, and decreases with increasing loading eccentricity. Based on the results from finite element analyses, several equations to calculate the maximum moment bearing capacities are put forward, which take the aspect ratio, loading eccentricity, and embedded depth into account.

Cyclic loading test study on a new cast-in-situ insulated sandwich concrete wall.

Insulated sandwich concrete panel (ISCP) is widely used because of its high thermal insulation efficiency and low construction cost. Aiming at improving traditional ISCP, a new cast-in-situ concrete wall structure made of ISCP is proposed, which is composed of thin-walled cold-formed steels, slant steel wire connectors, steel wire meshes, concrete layers, expanded polystyrene sheets and reinforced concrete embedded columns. In order to assess the hysteretic properties of the new insulated sandwich concrete wall and the influence of various parameters, low-frequency horizontal cyclic load tests were carried out on seven full-scale specimens of new type cast-in-situ insulated sandwich concrete wall. The specimens were compared and analyzed with respect to failure mode, bearing capacity, ductility, degradation characteristics and energy dissipation capacity. The results show that the final failure pattern of the specimen is two main diagonal cracks intersecting each other; the bearing capacity is greatly affected by concrete thickness and axial compression ratio, regardless of concrete strength. Brittle failure is typically observed when the steel wire spacing is large, while ductility is pronounced when the concrete layer thickness is small and the concrete strength is low; the smaller the thickness of concrete layer, the faster the stiffness degrades. The wall structure shows a better energy dissipation performance with a smaller steel wire spacing, lower concrete strength and smaller axial compression ratio.

Reinforcement by polyurethane to stiffness of air-supported fabric formwork for concrete shell construction

By spraying concrete on inner surface, air-supported fabric structures can be used as formwork to construct reinforced concrete shell structures. The fabric formwork has the finished form of concrete structure. Large deviation from the desired shape of concrete shells still remains as central problem due to dead weight of concrete and less stiffness of fabric formwork. Polyurethane can be used not only as a bonding layer between fabrics and concrete but also as an additional stiffening layer. However, there is little research on mechanical behaviors of the polyurethane shell structure. This paper presents experimental studies on an inflated fabric model with and without polyurethane, including relief pressure tests, vertical loading tests and horizontal loading tests. Experimental results show that the additional polyurethane layer can significantly enhance the stiffness of the fabric formwork. Compared with the experiment, a numerical model using shell layered finite elements has a good prediction. The reinforcement by polyurethane to improve stiffness of air-supported fabric formwork is expected to be considered in the design and construction of the concrete shell, especially dealing with the advance of shape-control.

Hollow block masonry wall reinforced by built-in structural configuration: Seismic behavior analysis

This paper proposes a new type of wall with built-in structural configuration. Common blocks with single-row holes serve as grouted recesses in the construction of built-in structural columns, core columns, and diagonal braces of the wall. The construction of this built-in structural scheme is more efficient and cost-effective than normal wall structures because it necessitates no formwork or large construction equipment. A nonlinear finite element analysis and integral modeling process were conducted based on horizontal cyclic loading tests of four hollow-block masonry walls with different built-in structural schemes. The feasibility of the model was verified by comparing the test and calculation results. The effects of different structural schemes on the failure process, failure mode, bearing capacity, stiffness degradation, and displacement ductility of the masonry wall were analyzed to determine the optimal structural details. The built-in structural columns and core columns should be concentrated at both wall ends while core columns are added in the center of the wall as necessary; a horizontal steel tie mesh can ensure cooperative bonding among structural columns and core columns. The effects of various strength grades of grouted concrete on masonry wall seismic performance with the optimized scheme were also observed.

A fracture energy based damage-plasticity interfacial constitutive law for discrete finite element modelling of masonry structures

The robust structural design relies on the accuracy of the response analysis to different loadings. Strut-and-tie models and continuum models are often used for the design of masonry structures but they are generally not able to simulate detailed damage and progressive collapse. To this regard, this paper presents a new and robust interfacial constitutive law, which couples the damage and plastic deformation with fracture energy-based softening rules, for the discrete finite element modelling (DFEM) of masonry structures. The model has 14 required parameters and 2 optional parameters of which calibration methods using the standard test data and physical rules are provided in details. It was demonstrated that the comprehensive mechanical behaviour including the pressure-dependent fracture, wearing-off of the friction, dilatation, stiffness degradation, shear retention, and component disintegration can be well captured. The model validation studies were performed with various material and structural tests including shear-compression and uniaxial tension tests on the joints, and horizontal loading and shake-table tests on large-scale masonry structures. Good agreements between the simulated and experimental results could be observed. Comparing to conventional modelling approaches, the DFEM with the interfacial constitutive law can also simply the meshing work and better control the mesh quality.

Repairing and Recovering Structural Performance of Earthen Walls Used in Japanese Dozo-Style Structures After Seismic Damage

Several traditional building group districts exist in Japan as a system for preserving the remaining historical villages and townscapes of the country, along with their surrounding environment. In the northern Kanto region of Japan, there remain examples of many dozo-style structures called “Dozo-dukuri,” forming a distinctive historical townscape. In the 2011 Tohoku Region Pacific Offshore Earthquake, the traditional townscapes and dozo-style structures of the Kanto region were seriously damaged. When restoring the walls of damaged dozo-style structures to a sound condition, demolishing and reconstructing all the mud requires considerable labor; moreover, few modern artisans can construct mud walls. However, if there was a method that could recover the structural performance of the walls immediately via partial repair, the restoration of the walls could again become economical. Therefore, in this study, we first surveyed the specifications of mud walls in the northern Kanto region. Then, we performed horizontal loading tests on full-scale walls produced according to the survey results to determine the structural performance of walls under a horizontal force, e.g., an earthquake. Further, a test specimen damaged by a horizontal force was repaired, and a horizontal loading test was performed again. The results elucidated the structural performance recoverability obtained by the proposed repair method.

Implant-to-bone force transmission: a pilot study for in vivo strain gauge measurement technique

The experimental determination of local bone deformations due to implant loading would allow for a better understanding of the biomechanical behavior of the bone-implant-prosthesis system as well as the influence of uneven force distribution on the onset of implant complications. The present study aimed at describing an innovative in vivo strain gauge measurement technique to evaluate implant-to-bone force transmission, assessing whether and how oral implants can transfer occlusal forces through maxillary bones.In vivo force measurements were performed in the maxillary premolar region of a male patient who had previously received a successful osseointegrated titanium implant. Three linear mini-strain gauges were bonded onto three different buccal cortical bone locations (i.e. coronal, middle, apical) and connected to strain measuring hardware and software. A customized screw-retained abutment was manufactured to allow for vertical and horizontal loading tests.As to the vertical load test, the patient was instructed to bite on a load cell applying his maximum occlusal force for 20 s and then recovering for 10 s to restore the bone unstrained state; the test was repeated 20 times consecutively. As regards the horizontal load test, the implant was subjected to a total of 20 load applications with force intensities of 5 and 10 kg. During the tests, the recorded signals were plotted in real time on a graph as a function of time by means of a strain analysis software.The described strain gauge measurement technique proved to be effective in recording the forces transmitted from osseointegrated implants to the cortical bone. Horizontal loads caused higher deformations of cortical bone than vertical biting forces; in both situations, the deformation induced by the force transferred from the implant to the bone progressively decreased from the coronal to the apical third of the alveolar ridge. At approximately 9 mm from the implant neck, the effect of occlusal force transmission through osseointegrated titanium implants was negligible if compared to the apical region.

Reversed horizontal cyclic loading tests of flat slab specimens with studs as shear reinforcement

The results of a series of experiments on four reinforced concrete flat slab specimens with shear studs and a control specimen without any shear reinforcement are presented. The specimens were tested under constant gravity loads and reversed horizontal cyclic displacements. The main test variables were the applied gravity load and the number of perimeters of studs. One of the specimens was tested in two phases to study the postearthquake behavior. Results showed a considerable improvement of the deformation capacity of specimens with studs compared to the reference specimen. In agreement with previous research, increasing the applied gravity shear ratio resulted in a lower experimental drift capacity. It is shown that a better explanation of the observed ultimate drifts can be made by considering also the flexural capacity and the extent of shear reinforcement. The specimen tested in two phases exhibited considerable residual capacity, even after severe horizontal loading.

Horizontal Loading Tests on Disconnected Piled Rafts and a Simplified Method to Evaluate the Horizontal Bearing Capacity

Disconnected piled raft (DPR) foundations have been widely adopted as an effective foundation system where the piles are separated from the raft by a granular layer, which can limit the shear forces and moments transmitted between the raft and the piles. Thus, DPR foundations may avoid the problem of horizontal forces, such as those from an earthquake or dynamic loads, which damage the structural connection between the pile head and raft. A series of static horizontal loading tests were carried out on three types of foundation models, i.e., piled raft, disconnected piled raft, and raft alone models, on fine sand using a geotechnical model in a 1 g field. In this paper, the influences of vertical loading and interposed layer thickness were presented and discussed. The results showed that most of the horizontal force was carried by raft/interposed layer friction in the DPR foundation type, and the shear force and moment of the piles were greatly reduced due to the gap between the raft and the heads of the piles. The tested foundations were simulated using a simplified method with theoretical equations derived by making several approximations and assumptions. The simulated results agreed well with the test results.

INTERACTION BETWEEN BEDDING SAND THICKNESS AND SHELL GROOVE-UNDERSIDE SHAPED CONCRETE BLOCK PAVEMENT

Underside Shaped Concrete Block (USCB) has groove shaped at the underside block surface to produce resistance in horizontal plane and to grip onto the bedding sand layer. However, the horizontal movement of block units is the major problem in pavement due to vehicle braking and accelerated action. This paper presents the laboratory evaluation on vertical and horizontal displacement of shell groove-USCB pavement laid onto different bedding sand layer thickness. A pavement laboratory test was conducted to investigate the interaction between USCB type of the Shell-Rectangular 15 mm (Shell-R15) and bedding sand on three different loose bedding sand layer thicknesses of 50 mm, 70 mm and 90 mm respectively. Then, push-in loading test and horizontal loading test were performed. The results showed that interaction between USCB Shell-R15 and bedding sand layer thickness had significant influence to the vertical and horizontal displacement compared to control of 50 mm loose bedding sand layer thickness. The loose bedding sand layer thickness of 70 mm performed better compared to others.

Field Test of Driven Pile Group under Lateral Loading

All the geotechnical works need to be tested because the diversity of soil parameters is much higher than in other fields of construction. Horizontal load tests are necessary to determine the lateral capacity of driven piles subject to lateral load. Various load tests were carried out altogether on the test field in Kutno (Poland). While selecting the piles for load tests, different load combinations were taken into account. The piles with diverse length were chosen, on the basis of the previous tests of their length and integrity. The subsoil around the piles consisted of mineral soils: clays and medium compacted sands with the density index ID>0.50. The pile heads were free. The points of support of the “base” to which the dial gauges (displacement sensors) were fastened were located at the distance of 0.7 m from the side surface of the pile loaded laterally. In order to assure the independence of measurement, additional control (verifying) geodetic survey of the displacement of the piles subject to the load tests was carried out (by means of the alignment method). The trial load was imposed in stages by means of a hydraulic jack. The oil pressure in the actuator was corrected by means of a manual pump in order to ensure the constant value of the load in the on-going process of the displacement of the pile under test. On the basis of the obtained results it is possible to verify the numerical simulations of the behaviour of piles loaded by a lateral force.

Experimental and numerical investigation into the load resistance and hysteretic response of rhombic grid hyperboloid-latticed shells

The rhombic grid hyperboloid-latticed shells (RGHLSs) in the China Comic and Animation Museum (CCAM) are located on the ground floor, and they sustain enormous vertical and horizontal loads induced from upper building structures on top of them. Each RGHLS consists of numerous bidirectional inclined major and secondary columns that intertwine with one another to form a rhombic grid with X-shaped joints. Without both horizontal circumferential members and horizontal lateral braces in the radial direction of the RGHLS, as well as the existence of significant difference of compressive stiffness between major and secondary columns, the RGHLS would ultimately fail in a complicated form of in-plane and out-of-plane multi-column interaction instability in addition to its overall twist deformation under relatively low vertical loads. Currently, no design method for estimating its design strength and safety is available. Therefore, the load-carrying capacity of the RGHLS must be examined experimentally. This paper selects the RGHLS denoted by Y4 in the structure of the CCAM as the prototype, and presents an experimental investigation of its reduced scale (1:1/4) test model. A loading protocol consisting of six loading phases has been devised in order to predict the static vertical and horizontal load resistance, and horizontal hysteretic response of the RGHLS by keeping the amplitudes of the vertical load constantly as 1.0, 1.4 and 1.6 times the vertical design load of the reduced-scale test model, respectively. The experimental results obtained indicate that the test model remains elastic under 1.8 times its design loads, which is commonly adopted as static structural strength limit in practical design in China. In addition, horizontal cyclic load test indicated that the reduced-scale test model demonstrated sufficiently large horizontal load-carrying capacity as well as exhibited stable and ample hysteretic curves even under 1.6 times vertical load actions without any obvious stiffness reductions. This study comprehensively introduces the experimental test schemes and deeply analyzes the experimental results, thus forming an important basis for designing the load-carrying capacity of such RGHLSs. Ultimately, according to the experimental loading protocol, numerical simulations and analyses of the test model have been conducted by adopting ANSYS 12.1. The interaction strength design curve of the test model under a combination of vertical and horizontal loads is also proposed by carrying out additional numerical simulations of the model. The FE and experimental results have been compared, and they correspond well to one another, indicating that the results of the reduced-scale test model are accurate enough and reliable.

Horizontal Displacement Control in Course of Lateral Loading of a Pile in a Slope

Standard procedures concerning axial and lateral capacity testing of foundation piles usually consist of a single loading cycle. Constant load steps or constant settlement increments may be applied in the test. Such a procedure significantly differs from in-situ conditions of pile loading, which can be cyclic – especially in the case of the constructions, which are subject to wind load. Several tests were performed to observe the behaviour of the driven piles subject to fast cyclic loading in horizontal direction (lateral load). The manner in which the load tests were performed made it possible to determine the displacement of the 40×40 cm pile in the least favourable loading scheme, i.e. the lateral load capacity of the pile oriented towards the embankment slope. The piles were originally designed for the foundation of noise barriers along the highway. Some of the piles were broken in course of driving and a cautious check of their behaviour under load was requested before the assembling of the entire structure. Eight load tests were carried out altogether. While selecting the piles for further load tests, the representativeness of the random sample was taken into account. The piles with diverse cross section and length were chosen, on the basis of the previous low strain tests of their integrity. The subsoil around the piles consisted of medium and coarse sands with the density index ID>0.67. The pile heads were free. The points of support of the reference frame to which the sensors were fastened were located at the distance of 0.6 m from the side surface of the pile loaded laterally. In order to assure the independence of measurement, additional control (verifying) geodetic survey of the displacements of the piles subject to the load tests was carried out. The research conducted at Wroclaw University of Technology made it possible to collect and summarize the results of displacement measurements in course of static load testing of driven piles in a slope. Only selected case studies of cyclic loading in horizontal (lateral) pile load tests are presented in the paper.