In-plane Lateral Cyclic Loading Research Articles

Experimental study on seismic behavior of fabricated lightweight steel solid waste High-strength foam concrete composite wall

In order to actively implement the “dual carbon” goal and promote the popularization and application of green energy-saving prefabricated buildings in low-rise and multi-storey residential structures in villages and towns, a prefabricated light steel solid waste high-strength foam concrete composite wall was proposed. The wall is composed of high-strength foam concrete, cold-drawn steel wire mesh and cold-formed steel, which can realize the integration of load-bearing and energy-saving of wall components. The failure characteristics, hysteresis characteristics, bearing capacity and deformation performance, stiffness degradation and energy dissipation capacity of the wall specimens with different structures were analyzed through monotonic load and in-plane lateral cyclic loading test on three different wall specimens. The results show that under the action of cyclic load, the wall specimens with three different structures all have shear failure, and the wall specimens without cold-formed steel at the ends have low bearing capacity and poor seismic behavior. The bearing capacity and seismic behavior of the wall specimens with cold-formed steel at the ends were significantly improved, and the cold-formed steel, cold-drawn steel mesh, and high-strength foam concrete had good coordination performance. Considering the inherent characteristics of foam concrete, based on the existing specifications, the formula for calculating the shear bearing capacity of the prefabricated light steel solid waste high-strength foam concrete composite wall is given. The shear bearing capacity of wall members with different structures, different loading methods and different axial compression ratios are tested and calculated, and the calculated results of shear bearing capacity are in good agreement with the test results.

Comparison of Seismic Response Corner Beam-Column Joint with and without Fuse Bars Under In-Plane Lateral Cyclic Loading

Two full-scale corner beam-column joints with and without fuse bars were designed, constructed, tested, analyzed and modeled under in-plane lateral cyclic loading presented herein. The first specimen was designed using Eurocode 8 and equipped with four fuse bars. Second specimen was designed using BS8110 (non-seismic code of practice) with corbel. All the specimens have similar size of foundation beams, columns and beams. Visual observation during testing showed that specimen with fuse bars suffered less damage as compare with specimen without fuse bars. Furthermore, specimen with fuse bars has higher lateral strength capacity, stiffness, ductility and equivalent viscous damping than specimen without fuse bars. Finally, there is good agreement of lateral strength capacity, ductility, stiffness and equivalent viscous damping which lies between 2% and 20% between experiment and modeling hysteresis loops. Thus, it is recommended that fuse bar as a green structural material can be installed inside the corner beam-column joint for RC buildings to cater strong earthquakes in high seismic regions.

Seismic Analysis of Single Unit Tunnel Form Building Subjected to In-Plane Lateral Cyclic Loading Using Ruaumoko 2D Programme

Seismic effect to the tunnel form building (TFB) will vary depending on the location of the epicentre, magnitude and frequency of the seismic event. This effect can be mitigated by implementing a seismic analysis using the Ruaumoko 2D programme. The seismic analysis was conducted to examine the safety level of the TFB when it was subjected to 10 previous seismic events. The analysis emphasized the in-plane direction of lateral cyclic loading. The 10 selected seismic excitations were Pacoima Dam, El Centro North-South and East-West, Mexico City, Ranau, Lahad Datu, Kunak, Batu Niah, Manjung and Bukit Tinggi. The analysis results of tunnel form building (TFB) in terms of spectral displacements, earthquake excitations, pseudo-spectral acceleration and deformed shape of single unit tunnel form building obtained in this study. Based on these analyses, tunnel form building (TFB) can only withstand low seismic loading with far-field earthquakes. When subjected to a seismic load greater than 5 Richter Scale and near field excitation, tunnel form building will not safe to be occupied.

Cyclic Behaviour of Beam-Column Joints with Corbels Under In-Plane Lateral Loads

Corbels appearance in precast beam-column joints has a significant impact on the behaviour of the transition zone at the end of the beam which could help in delaying the yielding of the top reinforcement bars and increase the stiffness of the joint. The presence of corbels also released the development of unnecessary strain at the top of the internal reinforcement bars. Hence, the main objective of this paper is to access the emulative approach for beam-column joints with corbels in terms of structural behaviour for any seismic action through experimental work. Comparison of the experimental hysteresis loops (load versus displacement) and seismic performance for the three types of joints were made. Three full-scale sub-assemblages of corner, exterior and interior precast beam-column joints with corbel were designed using BS8110 Code of Practice. These three specimens were constructed and tested in a heavy structural laboratory under in-plane lateral cyclic loading. The corner, exterior and interior beam-column joints were tested starting from ±0.01% until 1.35% drift, ±1.00% drift and ±1.15% drift, respectively. This study found that the existence of corbels in precast joints can delay the yielding of the top reinforcement bars and increase the stiffness of the joint. However, the experimental result has proved that the corbel for corner beam-column joint was the weakest point of the joint based on the crack damaged at the corbel. On the other hand, the experimental work found that precast beam-column corner joint specimen exhibited 21.5% more ductile behaviour as compared to other two specimens. However, the ductility values for all specimens were recorded at less than 3, indicating that precast beam-column joint specimens were not able to take moderate to strong earthquake excitation.

Seismic response of precast and IBS buildings under earthquake attacks

Poor performances of precast buildings during earthquakes were due to inadequate connections between the structures components, insufficient seating and anchorage and poor workmanship and quality materials used. It is important to investigate their seismic performance by conducting experimental work, analyzing the data and modelling them using nonlinear time history analysis of the earthquakes. Three types’ structural components of precast structures and Industrialized Building System (IBS) were designed, constructed, tested, analyzed and modelling in this chapter. There structural components are precast shear-key wall panel, beam-column joints and tunnel form building system. All these specimens were tested under in-plane lateral cyclic loading. The seismic performance parameters such as lateral strength capacity, stiffness, ductility and equivalent viscous damping were evaluated using the measured hysteresis loops from experimental work. The findings from this research work can be implemented and enforced by government and local authorities to pay special attention to joint detailing of precast structures components while constructing the precast buildings. The design concepts and detailing of the jointing precast structural components contribute significantly to the overall seismic performance of precast buildings under earthquakes excitations. A lot of structural damages occurred during earthquakes due to not using the current seismic code of practice and poor detailing especially at the jointing system.

Experimental Study on Seismic Strengthening of Confined Masonry Walls Using RPC

Masonry structures without effective reinforcement are vulnerable to seismic excitation. An innovative strengthening technique was proposed for damaged and undamaged masonry walls. Six confined masonry units with two aspect ratios were tested under in-plane lateral cyclic loading, which consisted of two control walls, two original walls strengthened with reactive powder concrete (RPC-1), and two damaged walls repaired with RPC (RPC-2). The results of the specimens retrofitted with RPC demonstrated that the proposed technique significantly enhanced the seismic performance of masonry walls in terms of lateral strength, ductility, and energy dissipation. Furthermore, the two repaired specimens had a better distributed cracking pattern than the two strengthened specimens. The analysis of the results leads to a better understanding of the effect and mechanism of RPC seismic retrofitting for confined masonry walls.

Validation of Corner Beam-column Joint’s Hysteresis Loops between Experimental and Modelled using HYSTERES Program

The beam - column joint is an important part of a multi-storey RC building as it caters for lateral and gravitational load during an earthquake event. The beam-column joints should have a medium to high ductility for transferring the earthquake load and gravity load to the foundation. By designing multi-storey RC buildings using Eurocode 8 can avoid any diagonal shear cracks in column which is a major problem in non-seismic design buildings using British Standard (BS8110). This paper presents the experimental hysteresis loops of monolithic corner beam-column joints of multi-storey building which had been designed using Eurocode 8 and tested under in-plane lateral cyclic loading. The experimental hysteresis loops of corner beam-column joint was compared with modelled using the HYSTERES program. The full-scale corner beam-column joint of a two story precast school building was designed, constructed, tested and modelled is presented herein. The seismic performance parameters such as lateral strength capacity, stiffness, ductility and equivalent viscous damping were compared between experimental and modelled hysteresis loops. The experimental hysteresis loops have similar shape with the modeling hysteresis loops with small percentage differences between them.

Seismic Behavior of Tunnel Form Building under Lateral Cyclic Loading

A three-story single-unit tunnel form building (TFB) was designed using a non-seismic code of practice (BS 8110). Two one-third scale test models were constructed and tested under in-plane lateral cyclic loading and out-of-plane lateral cyclic loading, respectively. The specimens were tested at ±0.01%, ±0.1%, ±0.25%, ±0.5%, ±0.75%, ±1.0%, ±1.25%, ±1.5%, ±1.75% ±1.8, ±1.9% and ±2% drifts, after which severe cracks were observed on the wall-slab joints and wall panels. Subsequently, the damaged specimens were repaired and retrofitted by wrapping carbon fiber reinforced polymer (CFRP) around the damaged walls and affixing steel plates and steel angles at the wall-slab joints using several different repair and retrofitting schemes. The repaired specimens were retested using the same drifts. The comparison of the seismic behavior between unrepaired and repaired specimens was made based on visual observation of damage, hysteresis loops, lateral strength capacity, stiffness, ductility, and equivalent viscous damping. The experimental results showed that the repaired specimens were improved in terms of damage, lateral strength capacity, stiffness, ductility, and equivalent viscous damping. It is recommended to strengthen and rehabilitate tunnel form buildings after an earthquake using CFRP, additional shear walls, steel plates and steel angles.

Experimental study on seismic behavior of repaired tunnel form building under cyclic loading

It is very important to determine the seismic behavior of the multi-story tunnel form buildings especially in medium and high seismic regions. The aim of this study is to determine the overall seismic behavior of unrepaired and repaired specimens under the in-plane lateral cyclic loading. The damaged specimen was repaired by enlarging the external shear wall, affixing the joints with steel plate and steel angle and finally wrapping the specimen with CFRP. A one-third scale double unit of tunnel form buildings was designed using non-seismic code of practice (BS8110), constructed and tested under in-plane lateral cyclic loading. The specimen was tested starting from ± 0.01, ± 0.1, ± 0.25, ± 0.5, ± 0.75%, until ± 2.3% drift. The repaired specimen was retested following a similar pattern of drifts as before repaired. The hysteresis loops of repaired specimen were modeled using HYSTERES program in Ruaumoko 2D. Experimental results showed that the repaired specimens improved in term of damages, 19.35% of lateral strength capacity, 6.79% of stiffness, 34.87% of ductility and 31.11% of equivalent viscous damping. There was good agreement between experimental hysteresis loops and modeling hysteresis loops. Thus, the damaged tunnel form buildings can be repaired, retrofitted and strengthened using the combination materials of steel plate, steel angle and CFRP.

Experimental and Analytical Evaluation of Confined Masonry Walls Retrofitted with CFRP Strips and Mesh-Reinforced PF Shotcrete

AbstractThis study evaluates the performance of retrofitted confined unreinforced masonry walls using carbon fiber–reinforced polymer (CFRP) strips and mesh-reinforced shotcrete. Polypropylene-fiber (PF) concrete was applied in the shotcrete retrofitting. Four full-scale confined unreinforced masonry walls were experimentally tested under in-plane lateral cyclic loading. The first nonretrofitted wall was built as a reference model. The second and third walls were retrofitted with carbon fiber–reinforced polymer strips in grid and diagonal layout, respectively. The fourth wall was retrofitted with mesh-reinforced PF shotcrete. The stiffness, strength, ductility, and modes of failure of the nonretrofitted confined masonry wall and the retrofitted confined masonry walls were determined and compared. The strength of the retrofitted walls with the grid and diagonal layout of carbon fiber–reinforced polymer increased up to 35 and 15%, respectively. However, the strength of the mesh-reinforced shotcrete retrofit...

Retrofitting of a Double Unit Tunnel Form Building Using Additional RC Wall, Steel Angle and CFRP

Tunnel form construction is widely known as modern construction method that enables the construction of horizontal and vertical elements simultaneously. It is quickly construct low cost, high quality and earthquake safe to construct cellular buildings. Main objective of this study is to determine the seismic retrofitting performance of a double unit tunnel form building when retrofitted using additional RC wall, steel angle and Carbon Fiber Reinforced Polymer (CFRP) when tested under in-plane lateral cyclic loading. A comparison of tunnel form building was made before and after retrofitting in terms of lateral strength, stiffness, ductility and equivalent viscous damping. Result indicates that retrofitting method using additional RC wall, steel angle and CFRP was able to increase the lateral strength, ductility and equivalent viscous damping under in-plane lateral cyclic loading. The result also shows the effectiveness of additional RC wall, steel angle and CFRP in improving the shear resistances and deformation capacities of concrete structures and delaying their stiffness degradation under earthquake loading.

Comparison of Seismic Performance between Single and Double Unit Tunnel Form Building under In-Plane Lateral Cyclic Loading

This paper summarizes the comparison of seismic performance between single and double unit tunnel form building (TFB) under in-plane lateral cyclic loading. Experimental work was carried out to determine the lateral strength capacity, stiffness, ductility, and equivalent viscous damping (EVD) for both specimens. The comparisons of these parameters for both specimens were made to determine its percentage difference. The maximum lateral strength capacity obtained from single unit TFB with 8.68% higher than double unit TFB. As for stiffness behaviour, single unit was found to be much more stiffened compared to double unit. The EVD value showed that single unit absorbed much more energy compared to double unit of TFB. However, double unit TFB indicated a significant percentage of increment compared to the single unit TFB. Therefore, double unit TFB is safer to be built compared to single unit especially for seismic regions.

Comparison of Seismic Behaviour for a Single Unit Tunnel Form RC Building before and after Repaired

Repairing and strengthening the structures are gaining more attention from many researchers and structural engineers after the structures suffered damages from natural disasters. Tunnel form RC buildings which are not designed according to seismic code of practice are very vulnerable to ground motion when located to near field earthquake. This paper presents the method of repair and strengthening of 3-storey tunnel form building subjected to in-plane lateral cyclic loading. The building was strengthened using the combination method of steel angle, steel plate and Carbon Fiber Reinforce Polymer (CFRP) sheet. The results show that the lateral strength capacity is increase by 15.66%, ductility increase by 53.57% and equivalent viscous damping increase by 28.88% for the first cycle and 33.65% for the second cycle. However, the stiffness of the structure reduce by 56.6%. It can be concluded that this method can be adopted for the damage of tunnel form building system.

Seismic Performance of Insulated Sandwich Wall Panel Subjected to Lateral Cyclic Loading

In this paper, the seismic performance of the insulated sandwich wall panel is studied. Two samples W1 and W2 of Insulated Sandwich Wall Panel (ISWP) were tested under in-plane lateral cyclic loading. The difference between W1 and W2 is the numbers of wall plug used in order to hold the specimen in standing parallel position. Four wall plugs used for W1 meanwhile eleven wall plugs used for W2. ISWP is placed axially on top of the foundation beam. The concrete block is slotted on top of the wall panel as load transfer from the roof. The aspect ratio of the specimen is Ar = H/B = 1.97 and slenderness ratio is λ = H/t = 36.92. The testing is conducted with small percent of drift which is 0.1% and continued with 0.2%. The drift was increased gradually about 0.2% until reach ±1.0%. Furthermore, the specimen was tested with an increment of ±0.2% drift until the specimens reach the strength capacity. The experimental results showed that for the first specimen, the wall panel behaves elastically up to 0.4% drift before yielding. Due to loading and unloading condition, the aluminium frame that used along the perimeter of the wall panel buckled at 1.2% drift. For the second specimen the wall panel behaves elastically up to 0.4% drift before yielding. Once 0.6% drift applied, crack started to appear at the connection joint between G.I channel and foundation beam. The analysis of the result from the graphs of hysteresis loop for both W1 and W2 were presented by considering the seismic parameter such as stiffness, ductility and equivalent viscous damping.

Validation Between Direct Displacement Based Approach and Experimental Work Using Precast Hollow Core Wall Panel

Existence of hollow sections in precast hollow core wall makes it sceptical to resist earthquake loading. However, this wall can resist earthquake loading if it is designed as a hybrid wall system. It is equipped with unbonded tendons and bonded “’fuse-bars” to dissipate energy. It rocks steel-on-steel without inducing any structural damages. In-plane lateral cyclic loading is applied on the wall. Experimental results show that the wall is able to resist earthquake loading without any structural damage. Direct displacement based approach is used to validate the experimental results. There are good correlations between them with very a small percentage of discrepancies.

In-Plane Testing of Damaged Masonry Wall Repaired with FRP

This paper describes the performance of a masonry wall repaired with glass fibre reinforced polymer, GFRP sheets. The original reinforced clay brick masonry wall was tested under in-plane lateral cyclic loading. Failure occurred due to yielding of the steel reinforcement and crushing of the bricks. After epoxy injection of the cracks and patching of the missing portions, the wall was repaired using GFRP sheets, applied in the horizontal and vertical directions, on one face of the wall, including the joint between the wall and concrete footing. The repaired wall was tested to failure in the same manner of the original wall. The results show that the strength and displacement capacities of the wall were completely restored and even exceeded the original capacities.