Pseudo-static Test Research Articles

Experimental and Numerical Investigation on Reinforced Concrete Beam-Column Joints

The elasto-plastic analysis of reinforced concrete square columns was introduced to study the relationship between lateral force and curvature by using the open source program OpenSees. A pseudo static test on the inverted "T" shape reinforced concrete square column was conducted for the comparative analysis. The results indicated that the lateral force calculated by program agree with experimental data with an axial load ratio of 0.33. The calculated yield lateral force was 29.7 kN, the error was lower than 7% compared with experimental results. In addition, the cross-section curvature were obtained, which were difficult to obtain through the traditional experimental study, the calculated yield curvature was 1.825×10-5. The calculated results with different axial load ratios were presented in this paper, which showed that both the yield lateral force and curvature of reinforced concrete square columns were increased with low axial load ratio, and at the same time it could reduce some experimental work by using computer simulation.

Experimental Research on the Seismic Behavior of Enclosing Masonry Walls Simulated the Structure of an Ancient Masonry Pagoda Strengthened with Steel Straps

in this paper, four single-layer masonry wall models in1/8 scale were made by a kind of special bricks on the basis of an ancient masonry pagoda structure. The models are divided into two groups by whether there is a masonry floor in a model or not. Pseudo-static test is introduced to study the seismic performance of four models with a special load control process which is suited to masonry structure. According to the test results, the horizontal bearing capacity and ductility of each masonry walls reinforced with steel straps under horizontal low cyclic loading has been sorted out. Four nonlinear restoring force models are inferred from the experimental results and phenomena under various operating conditions. And the shear capacity calculation formula of reinforced masonry wall models is fit out. The theory and experimental study show that seismic performance of the masonry pagodas strengthened with steel straps has been improved significantly.

Experimental Study on Mechanical Behavior of Wind Turbine Frustum Tower

One scale model of 1.5MW wind turbine frustum tower in Baiyun Obo was carried on pseudo-static test. The failure mechanism and characteristics, stress changes and distribution laws, hysteresis performance and ultimate bearing capacity were studied. Test results show that the wind turbine tower belong to the sudden extreme point instability failure; the buckling bearing capacity is as the ultimate bearing capacity of tower. The maximum stresses of tower mainly distribute at the variable wall thickness section and bottom, while other parts basically dont yield. This indicate that the material utilization of this kind of tower structure remains relatively low, structural design has yet to be improved, at the same time recommends that reasonable strengthen measures should be taken at the weakest part of tower. The P-Δ hysteretic curve of tower shows anti-"S" shape, the overall strength and stiffness degenerate more rapidly, which indicates that the plastic deformation and energy dissipation capacity of frustum tower is poor. The test conclusions could reflect the stress condition of prototype tower and provide references for design.

Experimental Study for Seismic Performance of Confined Masonry Structure

A two-story masonry housing model was made in this paper. According to Intensity 7, adjusted Northridge record was selected to be the ground motion input in the pseudo-dynamic test. Pseudo-dynamic test and pseudo-static test were carried out to investigate the seismic behavior of the model structure. The time-history curves of the acceleration, velocity, displacement and restoring force of the structural response were obtained besides the time-history curves of the measuring points of the structure. Also the steel strain of the tie-columns and the hysteresis loops of the structure were obtained. The result shows multi-story confined masonry structures possess superior seismic performance if coordinated with the provision specified in the current compulsory design code and it can continue to use after appropriate dressing under the rarely earthquake.

Research on the Joint of Concrete-Filled Steel Tubular Column and Steel Beam

With the pseudo-static test of 4 concrete-filled square steel tubular column and steel beam joint with outer stiffened ring, this paper discusses the failure characteristics, failure mechanism and seismic behavior of joints under different axial compression ratio. The analysis of the testing results shows: when reached the ultimate strength, the strength degradation and stiffness degradation of joints are slowly and the ductility is also good, the energy dissipation capacity of joints is much better.

Seismic Performance Experimental Research of Added Ring-Beams and Tie-Columns Masonry Structure

To research seismic performance of the strengthened masonry structure, the two stories masonry structure housing model with added ring-beams and tie-columns was designed and made in this paper. By inputting acceleration time-history curve of rarely earthquake of Intensity 7, the seismic response of acceleration, speed, restoring force and displacement of the strengthened masonry structure were obtained through the pseudo-dynamic test when rarely earthquake of Intensity 7 occurred. The reinforcement strain time-history curves of tie-columns root and beam-column junction were tested, then the restoring force-displacement curve of the structure was obtained. By method of pseudo-static test, the strengthened masonry structure of the ultimate limit bearing capacity, limit deformation were obtained, the cracking part and developing process were observed. Finally, comparing the data in this test with that test result of the ring-beams and tie-columns masonry structure designed based on current codes; analyzed seismic performance of the strengthened masonry structure when rarely earthquake of Intensity 7 occurred.

Experimental Studies on Transfer Beam Supported Frame Equipped with Fiber Reinforced Plastics Bars

Through pseudo static test on three pieces of fiber reinforced plastics (FRP) transfer beam supported frame with three different reinforcement form, reinforcement ratio and the number of root reinforcement ,which are subjected to the vertical load and horizontal low cycle reciprocating load, the specimen fracture development law, yield mechanism, failure pattern, and bearing capacity, ductility, hysteresis characteristics and seismic performance are analyzed. The test results show that: yield mechanism and failure pattern of transfer beam supported frame equipped with fiber reinforced plastics reinforced bars are reasonable. The bearing capacity and deformation performance of transfer beam supported frame with top and bottom longitudinal bar replaced by FRP bars and symmetrical reinforced box are better than that of single upper replacement for FRP and lower replacement for FRP. The ductility performance of transfer beam supported frame equipped with fiber reinforced plastics bars is good, hysteresis curve is full, and have good seismic performance.

Results of pseudo-static tests with cyclic horizontal load on cast in situ sandwich squat concrete walls

In recent years, the seismic behaviour of structural systems composed of squat concrete walls has been the object of a renewed interest. This paper presents the results obtained in a large experimental campaign carried out as a joint effort between the University of Bologna and the Eucentre labs in Pavia. This effort aims at the assessment of the seismic performances of cellular structures composed of cast in situ sandwich squat concrete walls. In order to shed light upon the seismic behaviour (stiffness, strength, ductility, energy-dissipation) of such structures, a number of tests were performed upon two dimensional (3.0m by 3.0m) cast in situ sandwich squat concrete walls (with and without openings). In the experimental tests a number of horizontal in-plane loading cycles were imposed to the specimens, while the vertical load was kept constant. The results obtained have shown that the tested elements are characterized by: (i) high values of the maximum horizontal load applied to the structural systems (higher than the applied vertical load); (ii) residual bearing capacity with respect to the vertical loads, also when large lateral deformations are imposed; and (iii) high ductility.

Lyophobic and Magnetized MWCNTs-Based Nanofluidic System: High-Performance Damping Structure

AbstractA high-performance damping structure was developed with lyophobic and magnetized multiwalled carbon nanotubes (MWCNTs)–based nanoporous composite and high surface tension liquids. The MWCNTs were surface treated by long-chain organic groups and decorated by ferroferric oxide (Fe3O4) nanoparticles. According to the X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) data, the grafting rate of organic groups and the decoration rate of ferroferric oxide were 5.56 and 1.13%, respectively. From the transmission electron microscope (TEM) and scanning electron microscopy (SEM) images, regular nanochannel structures and compact combination could be observed in the epoxy matrix. Pseudostatic and dynamic loading tests were performed. The results indicated that the MWCNT-based damping structure could achieve an infiltration pressure (yielding stress) up to 30 MPa, leading to a large energy dissipation capacity.

Study on Seismic Behavior of Transformed-Connection Joint in Light Steel Adding Storey

Based on the pseudo-static tests among three different types of joints (traditional planted-bar joint, the CFRP strengthening joint and the transformed-connection joint) between concrete frame and adding light steel storey, the research was carried out to contrast the seismic performance of these joints. The results showed that: three joints’ destruction was due to the plastic hinge and the maximum crack appearing at the end of beams, the seismic performance of the two new types of joints were better than the traditional planted-bar joint; Among the three joints, the hysteresis curve envelope area of CFRP strengthening joint was the biggest and the energy consumption was the most powerful; The stiffness of transformed-connection joint was improved significant, and its manufacture technology of joint was simple and convenient.

Experimental Study on Seismic Behavior of Strengthening Joints in Light Steel Adding Storey

In order to acquire the seismic performance of three different types of nodes between the concrete frame and the light steel adding storey, the pseudo-static tests were carried out to analyse contrastively these specimens’ failure modes, stiffness degradation, hysteretic curves and energy dissipation. The test results showed that : Three nodes’ destruction were due to the plastic hinges emerging at the end of beam; both encased steel and carbon fiber strengthening method can improve the seismic behavior, and in terms of the ultimate bearing capacity, energy consumption ability，the encased steel strengthening one can improved more significantly, and the encased steel one can effectively slow down the speed of stiffness degradation.

Experimental and Numerical Study on Seismic Performance of Flat Columns under Bilateral Cyclic Loading

In order to research seismic behavior of flat columns under bilateral cyclic loading with different angles, pseudo-static tests are conducted, which includes three 1:2 scaled flat columns. The height-width ratio of the column section is 5. And the loading directions are 00, 250 and 450 respectively. By observation of the test phenomenon and analysis of the data, the seismic performance of the columns including stiffness, skeleton curves, hysteresis curves, ductility and energy dissipation are obtained. Moreover, finite element program ANSYS is employed to simulate the bearing capacity of specimens. The research shows that with the loading angles increasing from 0 to 45, the strength of the flat column decreased gradually, while the ductility and energy dissipation capacity increase, and the failure mode changed from compression-shear to compression-bending. P-Δ effect becomes evident at lager values of loading angle. The compression-shearing curve of flat column complies with a heart-shape curve.

Experimental Study of CFRP Confined RC Rectangular Hollow Section Bridge Piers

To investigate the seismic performance of FRP strengthened RC hollow section bridge piers under multi-dimensional earthquake excitation, the pseudo-static test was carried out to RC rectangular hollow section as-built and CFRP confined bridge piers under constant axial compression force and bidirectional horizontal repeated load. The failure characteristics, lateral force-deformation curves and ductility of specimens were analyzed. The experimental result shows that CFRP constraining may change the failure mode of hollow section bridge piers, and significantly improve the deformation ductility, plastic deformation, however, it is less contribution to horizontal force of specimens with less wall-thickness.

Nonlinear Analysis on Stainless Steel Reinforced Concrete Columns under Low-Cyclic Load

In order to study the elastic-plastic mechanics properties of the stainless steel reinforced concrete columns under low-cyclic load, the engineering open-source earthquake simulation system OpenSees is used to carry out the numerical simulation. The comparison between the computed results and the pseudo-static test results shows that the OpenSees may stimulate the mechanical properties of the stainless steel reinforced concrete columns by using the fiber element model, both of the skeleton curves and hysteretic curves are well agreement with the tests results.

Discussion on Masonry Structure Model Mechanical Property Test

The problems in the mechanical test of masonry structure model were discussed in this paper, including the masonry material, similar relationship, shaking table test device, judgment of wall cracking and number of cycles in pseudo-static loading test. The conclusions are: (1) for the masonry material mechanical test, usually the size decreased the strength increased, but if the laying method and appropriate adjustments in the process of the test mixture ratio, the size effect can be greatly reduced; (2) In the dynamic test of the masonry structure, for the gravity distortion model, the common way is the external prestressing method, but in this method the tension force is not constant, which is differ from the actual situation; (3) The wall cracking can be judged when the main tension crack of the wall appeared; (4) The loading cycle in the pseudo-static test of masonry wall would be twice.

Seismic Damage Evaluation of Recycled Concrete Frame Using Wavelet Transform

According to the pseudo static tests on a two-storey and single-span concrete frame made with recycled aggregates, the failure pattern, hysteresis loop curves, displacement ductility of the recycled aggregate concrete frame are investigated. The time histories of loads and displacements are decomposed to four different levels by using the wavelet packet transform. Based on the decomposition coefficients on the 4th level, a seismic damage index is developed and presented in this paper. The cumulative damage process of this recycled aggregate concrete frame under low reverse cyclic loading is also analyzed by using this damage index. The experiment results clearly indicate that recycled aggregate concrete frames have excellent seismic behaviors. The damage index given in this paper can accurately and effectively reflect the severity of damage for structures under different loading states.

Study on Reinforced Concrete Masonry High-Rise Building by Abaqus

Pseudo static tests of 10 specimen made of 290 mm thick reinforced concrete masonry wall were finished, then test results were simulated by ABAQUS which use shell element, pamameters of the materials were defined by the comparison between the calculation results and that of the test. A 100 m high reinforced concrete masonry building in China was analyzed, elastic-plastic deformation check calculation under earthquake action by time-history analysis method were detailed. The story drift of the building is 1/666 for fortification intensity 6 and 1/326 for intensity 7 under strong earthquake, it is feasible.

Research on the Seismic Behavior of Concrete-Filled Steel Tubular Column and Steel Beam Joint

Joints are the forces cross points of members, and the bearing modes are more complex than other members, especially under earthquake action, so the rationality of joints are directly related to the safe reliability of structure. By the pseudo-static test of 4 concrete-filled square steel tubular column and steel beam joint with outer stiffened ring, this paper discusses the failure characteristics, failure mechanism and seismic behavior of joints under different axial compression ratio. The analysis of the testing results shows: the energy dissipation capacity of joints is much better, the degradation of strength and stiffness are slowly when reached the ultimate strength, and the ductility is also good.

Seismic Response of Ultra-High Performance Concrete-Filled FRP Tube Columns

The seismic response of a novel hybrid column made of a fiber-reinforced polymer (FRP) tube filled with ultra-high performance concrete (UHPC) was studied. A methodology was proposed to estimate the maximum ground acceleration capacity of five UHPC-filled FRP tubes (UHPCFFT) and one reference concrete (RC) column based on the results of their pseudo-static tests. The proposed analytical methodology can be applied to any pseudo-static test. The analysis showed 20% higher maximum ground acceleration capacity for the steel-free UHPCFFT column with a thin FRP tube, as compared to its RC counterpart. The results were further verified using a nonlinear dynamic simulation.

Seismic Behavior Test of Recycled RC Frame Column with Different Axial Compression Ratios

Recycled concrete is a kind of new construction materials, and now received more and more attention from researchers and engineers, since its application in engineering projects can well cater to the increasing requirements of development for economic and environment-friendly society. Based on the pseudo static test of five recycled reinforcement concrete frame columns with different experimental axial compression ratios from 0.3 to 0.65, their failure modes, failure mechanism, hysteretic behavior, skeleton curves, bearing capacity, rigidity, ductility and energy dissipation capacity were discussed. Some possible influence factors and disciplines were also selected and analyzed. The study indicates that recycled reinforcement concrete frame columns in the case of relative low axial compression ratios usually exhibited similar and steady mechanical properties with common concrete columns. With the increase of axial compression ratio, its ductility and energy dissipation capacity are decreased and destruction forms tended to obvious brittle fracture, though its bearing capacity could slightly rise. The test results and analysis also manifest recycled concrete had expectative application potentials in most case.