Pseudo-dynamic test of the steel frame - Shear wall with prefabricated floor structure

Qingning Li,Chun Han,Weishan Jiang,Junhong Yin,Lei Yan 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.2

Seismic behavior of new composite structural system with a fabricated floor was studied. A two-bay and three-story structural model with the scale ratio of 1/4 was consequently designed. Based on the proposed model, multiple factors including energy dissipation capacity, stiffness degradation and deformation performance were analyzed through equivalent single degree of freedom pseudo-dynamic test with different earthquake levels. The results show that, structural integrity as well as the effective transmission of the horizontal force can be ensured by additional X bracing at the bottom of the rigidity of the floor without concrete topping. It is proved that the cast-in-place floor in areas with high seismic intensity can be replaced by the prefabricated floor without pouring surface layer. The results provide a reliable theoretical basis for the seismic design of the similar structural systems in engineering application.

Research on prefabricated concrete beam-column joint with high strength bolt-end plate

Li Shufeng,Zhao Di,Li Qingning,Zhao Huajing,Zhang Jiaolei,Yuan Dawei 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.74 No.3

Many prefabricated concrete frame joints have been proposed, and most of them showed good seismic performance. However, there are still some limitations in the proposed fabricated joints. For example, for prefabricated prestressed concrete joints, prefabricated beams and prefabricated columns are assembled as a whole by the pre-stressed steel bar and steel strand in the beams, which brings some troubles to the construction, and the reinforcement in the core area of the joints is complex, and the mechanical mechanism is not clear. Based on the current research results, a new type of fabricated joint of prestressed concrete beams and confined concrete columns is proposed. To study the seismic performance of the joint, the quasi-static test is carried out. The test results show that the nodes exhibit good ductility and energy dissipation. According to the experimental fitting method and the “fixed point pointing” law, the resilience model of this kind of nodes is established, and compared with the experimental results, the two agree well, which can provides a certain reference for elasto-plastic seismic response analysis of this type of structure. Besides, based on the analysis of the factors affecting the shear capacity of the node core area, the formula of shear capacity of the core area of the node is proposed, and the theoretical values of the formula are consistent with the experimental value.

Study on Seismic Disaster Mechanism of Irregular C-Shaped Curved Bridge with High Piers

Li Qingning,Cheng Maili,Yin Junhong,Zhou Chunjuan 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.4

Based on multi-support excitation theory, an irregular C-shaped curved bridge model with high piers was made by taking scale proportion of 1:20 to conduct the seismic simulation shaking table test in this paper. Failure mode of high flexible piers and earthquake damage mechanism of the curved bridge with high piers in action of different seismic wave spectrum, different peak acceleration, and different local topography effect were studied. The results showed that the failure mode of high flexible pier presents obvious distributional flexible characteristics, #1 pier's cracks concentrated in range of 0.125L-0.46L (L is the height of the piers) from the bottom of the pier, while #2 and #3 pier’s cracks concentrated in range of 0.07L-0.625L from the bottom of the piers. Pier elevation difference significantly affected pier cracks development and bridges dynamic response. Accompanied with increase of load, the fundamental frequency curve presented decline in leveling off, while the damping increased gradually and the capacity of seismic energy dissipation of the structure enhanced. Dynamic responses of the curved bridge are different and presented different law when four different seismic waves were applied. When seismic loads increased from 120 gal to 360 gal, peak dynamic response basically presented linear growth. When seismic loads increased from 480 gal to 960 gal, considering the local topography effect, peak dynamic response significantly presented nonlinear growth. In action of seismic load of 960 gal, the displacements at the top of the #1 and #3 piers were up to 32.3 mm, showing that the seismic response was relatively large at head and tail section of bridge thus prone to cause beam dropping down.

Experimental study on a new type of assembly bolted end-plate connection

Shufeng Li,Qingning Li,Haotian Jiang,Hao Zhang,Lei Yan,Weishan Jiang 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.26 No.4

The bolted end-plate beam-column connections have been widely used in steel structure and composite structure because of its excellent seismic performance. In this paper, the end-plate bolted connection is applied in the concrete structure, A new-type of fabricated beam-column connections with end-plates is presented, and steel plate hoop is used to replace stirrups in the node core area. To study the seismic behavior of the joint, seven specimens are tested by pseudo-static test. The experimental results show that the new type of assembly node has good ductility and energy dissipation capacity. Besides, under the restraint effect of the high-strength stirrup, the width of the web crack is effectively controlled. In addition, based on the analysis of the factors affecting the shear capacity of the node core area, the formula of shear capacity of the core area of the node is proposed, and the theoretical values of the formula are consistent with the experimental value.

Experimental Study on Y-shaped Bridge Under 3-dimentional Earthquake Ground Motions

Yan Lei,Li Qingning 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.6

Based on similar theory and multi-dimensional seismic design theory, a Y-shaped bridge model with the scale ratio of 1:20 was made to conduct the seismic simulation shaking table test in this paper. Failure mode and dynamic responses of Y-shaped bridge under different seismic wave spectrum, different peak accelerations and different seismic excitation directions were studied. The experimental results show that, the piers mostly exhibit bending failure mode and the vertical ground motion has a great influence on the development of cracks in girders. Dynamic responses of the Y-shaped bridge are different and presented different laws when three different seismic waves were applied. Seismic wave is input along the direction of the branch straight girder, which is the most unfavorable earthquake input direction when calculating the peak acceleration at the top of piers. Multi-dimension seismic excitation should be considered when calculating the width of the expansion joint between adjacent girders. The horizontal bidirectional seismic excitation can satisfy the design requirements of strain response at the bottom of pier. The model structure would cause vertical vibration during its horizontal seismic excitation, and vertical seismic excitation exerts more significant influence on the vertical vibration of branch straight girder.

Study on seismic performance of connection joint between prefabricated prestressed concrete beams and high strength reinforcement-confined concrete columns

Haotian Jiang,Qingning Li,Weishan Jiang,De-Yi Zhang 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.2

As the common cast-in-place construction works fails to meet the enormous construction demand under rapid economic growth, the development of prefabricated structure instead becomes increasingly promising in China. For the prefabricated structure, its load carrying connection joint play a key role in maintaining the structural integrity. Therefore, a novel end plate bolt connecting joint between fully prefabricated pre-stressed concrete beam and highstrength reinforcement-confined concrete column was proposed. Under action of low cycle repeated horizontal loadings, comparative tests are conducted on 6 prefabricated pre-stressed intermediate joint specimens and 1 cast-inplace joint specimen to obtain the specimen failure modes, hysteresis curves, skeleton curves, ductility factor, stiffness degradation and energy dissipation capacity and other seismic indicators, and the seismic characteristics of the new-type prefabricated beam-column connecting joint are determined. The test results show that all the specimens for end plate bolt connecting joint between fully prefabricated pre-stressed concrete beam and highstrength reinforcement-confined concrete column have realized the design objectives of strong column weak beam. The hysteretic curves for specimens are good, indicating desirable ductility and energy dissipation capacity and seismic performances, and the research results provide theoretical basis and technical support for the promotion and application of prefabricated assembly frames in the earthquake zone.

Large-scale pilot test study on bearing capacity of sea-crossing bridge main pier pile foundations

Zhang, Xuefeng,Li, Qingning,Ma, Ye,Zhang, Xiaojiang,Yang, Shizhao Techno-Press 2014 Geomechanics & engineering Vol.7 No.2

Due to the sea-crossing bridge span is generally large and main pier pile foundations are located in deep water and carry large vertical load, sea-crossing bridge main pier pile foundations bearing mechanism and load deformation characteristics are still vague. Authors studied the vertical bearing properties of sea-crossing bridge main pier pile foundations through pilot load tests. Large tonnage load test of Qingdao Bay Bridge main pier pile program is designed by using per-stressed technique to optimize the design of anchor pile reaction beam system. Test results show that the design is feasible and effective. This method can directly test bearing capacity of main pier pile foundations, and analysis bearing behaviors from test results of sensors which embedded in the pile. Through test study the vertical bearing properties of main pier pile foundation and compared with the generally short pile, author summarized the main pier pile foundations vertical bearing capacity and the main problem of design and construction which need to pay attention, and provide a reliable basis and experience for sea-crossing bridge main pier pile foundations design and construction.

Seismic tests of RC shear walls confined with high-strength rectangular spiral reinforcement

Huajing Zhao,Qingning Li,Can Song,Haotian Jiang,Jun Zhao 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.24 No.1

In order to improve the deformation capacity of the high-strength concrete shear wall, five high-strength concrete shear wall specimens confined with high-strength rectangular spiral reinforcement (HRSR) possessing different parameters, were designed in this paper. One specimen was only adopted high-strength rectangular spiral hoops in embedded columns, the rest of the four specimens were used high-strength rectangular spiral hoops in embedded columns, and high-strength spiral horizontal distribution reinforcement were used in the wall body. Pseudo-static test were carried out on high-strength concrete shear wall specimens confined with HRSR, to study the influence of the factors of longitudinal reinforcement ratio, hoop reinforcement form and the spiral stirrups outer the wall on the failure modes, failure mechanism, ductility, hysteresis characteristics, stiffness degradation and energy dissipation capacity of the shear wall. Results showed that using HRSR as hoops and transverse reinforcements could restrain concrete, slow load carrying capacity degeneration, improve the load carrying capacity and ductility of shear walls; under the vertical force, seismic performance of the RC shear wall with high axial compression ratio can be significantly improved through plastic hinge area or the whole body of the shear wall equipped with outer HRSR.

Research on anti-seismic property of new end plate bolt connections - Wave web girder-column joint

Haotian Jiang,Qingning Li,Lei Yan,Chun Han,Wei Lu,Weishan Jiang 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.22 No.1

The domestic and foreign scholars conducted many studies on mechanical properties of wave web steel beam and high-strength spiral stirrups confined concrete columns. Based on the previous research work, studies were conducted on the anti-seismic property of the end plate bolt connected wave web steel beam and high-strength spiral stirrups confined concrete column nodes applied with pre-tightening force. Four full-size node test models in two groups were designed for low-cycle repeated loading quasi-static test. Through observation of the stress, distortion, failure process and failure mode of node models, analysis was made on its load-carrying capacity, deformation performance and energy dissipation capacity, and the reliability of the new node was verified. The results showed that: under action of the beam-end stiffener, the plastic hinges on the end of wave web steel beam are displaced outward and played its role of energy dissipation capacity. The study results provided reliable theoretical basis for the engineering application of the new types of nodes.

Research on rotation capacity of the new precast concrete assemble beam-column joints

Chun Han,Qingning Li,Xin Wang,Weishan Jiang,Wei Li 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.22 No.3

The joints of the new prefabricated concrete assemble beam-column joints are put together by the hybrid joints of inserting steel under post-tensioned and non-prestressed force and both beams and columns adopt prefabricated components. The low cyclic loading test has been performed on seven test specimens of beam-column joints. Based on the experimental result, the rotation capacity of the joints is studied and the <i>M</i>-<i>θ</i> relation curve is obtained. According to Eurocode 3: Design of steel structures and based on the initial rotational stiffness, the joints are divided into three types; by equivalent bending-resistant stiffness to the precast beam, the equivalent modulus of elasticity <i>E_e</i> is elicited with the superposition method; the beam length is figured out that satisfies the rigid joints and after meeting the requirements of application and safety, the new prefabricated concrete assemble beam-column joints can be regarded as the rigid joints; the design formula adopted by the standard of concrete joint classification is theoretically derived ,thereby providing a theoretical basis for the new prefabricated concrete structure.