Seismic Performance of Hybrid Corrosion-Free Self-Centering Concrete Shear Walls

Reinforced concrete (RC) walls are extensively used in high-rise buildings to resist lateral loads, while ensuring an adequate level of ductility. Durability problems, including corrosion of conventional steel reinforcements, necessitate exploring alternative types of reinforcement. The use of glass fiber reinforced polymer (FRP) bars is a potential solution. However, these bars cannot be used in seismic applications because of their brittleness and inability to dissipate seismic energy. Superelastic shape memory alloy (SMA) is a corrosion-free material with high ductility and unique self-centering ability. Its high cost is a major barrier to use in construction projects. The clear advantage of utilizing both SMA and FRP to achieve durable self-centering structures has motivated the development of a composite SMA-FRP bar. This paper investigates the hybrid use of FRP bars and either SMA bars or composite SMA-FRP in concrete shear walls. An extensive parametric study was conducted to study the effect of different design parameters on the lateral performance of hybrid RC walls. The seismic behavior of the hybrid walls was then examined. The hybrid walls not only solved the durability problem but also significantly improved the seismic performance.

Racking performance of poplar laminated veneer lumber frames and frame-shear hybrid walls

This study examined the racking performance of poplar laminated veneer lumber (LVL) frames using bolted steel filling plates to connect beam-column joints, poplar LVL frames using the embedment bars to connect beam-column joints, and frame-shear hybrid walls made of poplar LVL studs and oriented strand board (OSB) sheathing panels. A new design load spreader beam was used on the side of the top of a specimen to apply monotonic and cyclic loadings. It was found that the lateral force resistance, stiffness, and ultimate loads of poplar LVL pure frames with bolted steel filling plate connections and closed rod connections were much lower than those of the poplar LVL frame-shear wall hybrid structure. The highest initial stiffness of the poplar LVL hybrid frame-shear wall was 1.77 kN/mm, which was 24% and 22% lower than that of the conventional shear wall made with spruce-pine-fir studs and OSB or plywood sheathing panels, respectively. The poplar LVL frame-shear wall hybrid structure showed lower degradation in stiffness than the conventional shear wall. The hybrid frame-shear wall structures made of poplar LVL could meet the requirements of Chinese standard; however, diagonal braces were required in use of poplar LVL pure frames.

Theoretical Study on Steel Reinforced Concrete Hybrid Walls with Centered and Staggered Openings

Buildings placed in seismic areas are designed to simultaneously ensure strength, ductility and stiffness during earthquakes. In most cases the lateral resisting system is composed by shear walls. Lately for mid and high rise buildings the solution to use steel reinforced concrete shear walls, called hybrid walls, has been used. In most cases, the shear walls provided to limit the lateral displacement of the buildings, need to have openings due to architectural requirements. The existing theoretical and experimental studies presented in the literature refer to the behavior of solid/plain walls and a lack of information was identified for hybrid walls with openings. A theoretical and experimental program was developed at Politehnica University Timisoara, Romania with the aim to study the behavior of hybrid walls with centered and staggered openings. The current paper presents the results of nonlinear finite element analyses using ATENA package performed in order to assess the structural capabilities of the proposed experimental specimens with openings. Using the results obtained in one previous experimental program, consisting in tests on 1:3 scale steel-concrete composite elements, the paper presents a comparative study regarding the behavior of hybrid walls with openings versus solid walls. The study is focused on nonlinear behavior of elements with key parameters being evaluated, i.e. maximum load, deformation capacity and stiffens degradation.

Tests on Seismic Behaviors of Double Thin Skin Hybrid Walls Filled with Demolished Concrete Lumps

Double thin skin hybrid walls filled with demolished concrete lumps (DCLs) are composed of two steel plate skin connected by rib plates, with the space between them filled with new concrete and demolished concrete lumps. In order to investigate the seismic behavior of double thin skin hybrid walls filled with DCLs, quasi-static tests of seven specimens were conducted. The parameters considered in the tests are: replacement ratio of DCLs, thickness of steel plate, axial load ratio, rib plate spacing and height-width ratio. Test results show that the seismic performances of double thin skin hybrid walls filled with DCLs are similar to the walls without DCLs, and the double thin skin hybrid walls filled with DCLs also exhibit acceptable ductility and energy dissipation ability.

Experimental Investigation on Soft-Story RC Frames Retrofitted by Hybrid Wall Technique

In this paper, a new retrofit method, which is called “Hybrid Wall Technique”, is proposed for retrofitting soft-story RC frames. In the proposed technique, steel plates encase the boundary RC columns, and connect to additional steel plates at the bay of the frame with the help of high-strength bolts. After installation of steel plates and high-strength bolts, which are also used as formworks, the additional concrete is cast. Structural performance of the proposed metho­­­d is verified by experimental investigations conducted on one-bay one-story RC frames. One non-retrofitted frame and three frames retrofitted by thick or thin hybrid walls were evaluated experimentally.