Seismic and Power Generation Performance of U-Shaped Steel Connected PV-Shear Wall under Lateral Cyclic Loading

BIPV is now widely used in office and residential buildings, but its seismic performance still remained vague especially when the photovoltaic (PV) modules are installed on high-rise building facades. A new form of reinforced concrete shear wall integrated with photovoltaic module is proposed in this paper, aiming to apply PV module to the facades of high-rise buildings. In this new form, the PV module is integrated with the reinforced concrete wall by U-shaped steel connectors through embedded steel plates. The lateral cyclic loading test is executed to investigate the seismic behavior and the electric and thermal performance with different drift angles. The seismic behavior, including failure pattern, lateral force-top displacement relationship, and deformation capacity, was investigated. The power generation and temperature variation on the back of the PV module and both sides of the shear wall were also tested. Two main results are demonstrated through the experiment: (1) the U-shaped steel connectors provide enough deformation capacity for the compatibility of the PV module to the shear wall during the whole cyclic test; (2) the electricity generation capacity is effective and stable during this seismic simulation test

Seismic Performance of SFRC Shear Walls with Window Opening and the Substitution Effect for Steel Bars

Shear walls are important vertical and lateral bearing element in structures. While shear walls with openings are fragile due to stress concentration and the quasi-brittle behavior of concrete in tension. Therefore, additional strengthening rebars are required for the shear walls with openings. However, it aggravates the problem of dense reinforcement which increases the steel cage manufacturing and concrete compaction problem and still lacks countermeasures against concrete damage and cracking. To reduce the rebar demand and improve the damage tolerance of squat reinforced concrete (RC) shear walls with openings, an optimized steel-fiber-reinforced concrete (SFRC) was adopted to understand the seismic performance by cyclical loading test. The tested specimens included a plain RC shear wall without strengthening bar around the opening (for comparison), an SFRC shear wall, and an SFRC shear wall with a reduced distributed steel bar. This paper mainly studies the effect of using SFRC to improve the seismic performance of the open shear wall and to replace the reinforcement around the opening and the shear reinforcement. The hysteresis curves, skeleton curves, stiffness degradation, bearing capacity degradation and energy dissipation of the specimens were analyzed. The results show that the failure can be delayed and relieved, the deformation capacity and energy dissipation can considerably improve, and rebars can be partially replaced by using SFRC

Interaction Mechanism of Cementitious Composites Containing Different Twisted PVA Fiber Bundles

Fiber-reinforced cementitious composites (FRCCs) have made significant progress in improving the tensile and flexural properties of concrete members. Studies have shown that polyvinyl alcohol (PVA) fibers can effectively enhance the toughness of FRCCs, but the haphazard distribution of short-cut fibers makes it difficult to give full play to the high tensile strength of the fibers, and it is difficult for bundled fibers to effectively bond with the concrete substrate, which has become a challenge in the study of changing materials. Twisting the fibers by a physical process to improve the bonding performance of PVA fibers with FRCC substrate is a safe and feasible solution. However, research on silicate cementitious composites reinforced with twisted PVA fibers is limited. In this study, the interaction mechanism of through-length twisted PVA FRCCs with different twist factors and fiber bundle numbers was investigated. A concrete matrix material configured from silicate cement, fly ash, silica fume, and medium sand, in which PVA fibers with different twist factors were pre-incorporated, was used for the tests. Three-point bending tests were carried out on specimens with different twist factors (0, 50, 100, and 150 twists per meter) and fiber bundle numbers 1, 2, and 3. Compared to the untwisted PVA fiber specimens, the twist factor of 100 and the single fiber bundle specimens showed significant improvements in the bending properties, including a 36% increase in deflection, a 68% increase in the equivalent bending stress, and a 119% increase in energy consumption. Micro-X-ray computed tomography scans showed improved bending properties and energy consumption capabilities due to enhanced bonding properties as a result of the increased fiber–matrix interaction area and surface toughness

Study on Perforation Behavior of PTFE/Al Reactive Material Composite Jet Impacting Steel Target

To study the penetration and cratering effect of reactive material composite jets, a series of experiments are carried out for the shaped charge (SC) with different composite liners damaging steel targets. The inner layer of composite liners is metal and the outer one is a polytetrafluoroethylene/aluminum (PTFE/Al) reactive material. Copper (Cu), titanium (Ti) and Al inner liners are used in this paper. The reactive material liner is composed of 73.5 wt.% PTFE and 26.5 wt.% Al powder through mass-matched ratios. Reactive material composite liners are prepared through machining, cold pressing and a sintering process. The SC mainly consists of a case, a composite liner, high-energy explosive and an initiator. The steel target is steel 45#, with a thickness of 66 mm. A standoff of 1.0 CD (charge diameter) is selected to conduct the penetration experiments. The experimental results show that when the inner layer of the composite liner is composed of Ti and Al, the hole diameters on the steel target formed by the reactive material composite jet are significantly larger than that of the inner Cu liner. By introducing the initiation delay time (τ) and detonation-like reaction model of PTFE/Al reactive materials, an integrated numerical simulation algorithm of the penetration and detonation-like effects of reactive material composite jets is realized. Numerical simulations demonstrate that the initial penetration holes on the steel targets are enlarged under the detonation-like effects of PTFE/Al reactive materials, and the simulated perforation sizes are in good agreement with the experimental results

Smart Elasto-Magneto-Electric (EME) Sensors for Stress Monitoring of Steel Cables: Design Theory and Experimental Validation

An elasto-magnetic (EM) and magneto-electric (ME) effect based elasto-magneto-electric (EME) sensor has been proposed recently by the authors for stress monitoring of steel cables with obvious superiorities over traditional elasto-magnetic sensors. For design optimization and engineering application of the EME sensor, the design theory is interpreted with a developed model taking into account the EM coupling effect and ME coupling effect. This model is able to approximate the magnetization changes that a steel structural component undergoes when subjected to excitation magnetic field and external stress, and to simulate the induced ME voltages of the ME sensing unit located in the magnetization area. A full-scale experiment is then carried out to verify the model and to calibrate the EME sensor as a non-destructive evaluation (NDE) tool to monitor the cable stress. The experimental results agree well with the simulation results using the developed model. The proposed EME sensor proves to be feasible for stress monitoring of steel cables with high sensitivity, fast response, and ease of installation

Mechanical Properties and Microstructure of Highly Flowable Geopolymer Composites with Low-Content Polyvinyl Alcohol Fiber

Geopolymer enhances mechanical properties with polyvinyl alcohol (PVA) fibers, but there has been limited research exploring low PVA fiber dosages for mechanical properties in 3D printing or shotcrete. This study experimentally investigated slag and fly ash-based geopolymer mixtures reinforced with 0.1%, 0.15%, and 0.2% PVA fiber by volume as well as a control group without PVA fibers. These mixtures were prepared using fly ash, quartz sand, slag powder, silica fume, and an aqueous sodium silicate solution as the alkali activator, with the addition of PVA fiber to enhance composite toughness. The mechanical properties of the composites, encompassing dog-bone tensile properties, cubic compressive strength, bending and post-bending compressive strength, and prism compressive properties, were evaluated. Significantly, specimens with 0.15% PVA fibers exhibited optimal performance, revealing a notable 28.57% increase in tensile stress, a 36.45% surge in prism compressive strain, and a 47.59% rise in tensile strain compared to fiber-free specimens. Furthermore, environmental scanning electron microscopy observations were employed to scrutinize the microscopic mechanisms of composites incorporating PVA fibers, slag, and fly ash. In comparison to fiber-free specimens, prism compressive specimens with 0.15% PVA fibers demonstrated a 27.17% increase in post-cracking loading capacity, a 44.07% increase in post-cracking ductility, a 50.00% increase in peak strain energy, and a 76.36% increase in strain energy ratio

Mesenchymal-Stem-Cell-Based Strategies for Retinal Diseases

Retinal diseases are major causes of irreversible vision loss and blindness. Despite extensive research into their pathophysiology and etiology, pharmacotherapy effectiveness and surgical outcomes remain poor. Based largely on numerous preclinical studies, administration of mesenchymal stem cells (MSCs) as a therapeutic strategy for retinal diseases holds great promise, and various approaches have been applied to the therapies. However, hindered by the retinal barriers, the initial vision for the stem cell replacement strategy fails to achieve the anticipated effect and has now been questioned. Accumulating evidence now suggests that the paracrine effect may play a dominant role in MSC-based treatment, and MSC-derived extracellular vesicles emerge as a novel compelling alternative for cell-free therapy. This review summarizes the therapeutic potential and current strategies of this fascinating class of cells in retinal degeneration and other retinal dysfunctions

Mapping the galvanic corrosion of three coupled metal alloys using coupled multielectrode array:Influence of chloride ion concentration

The galvanic corrosion behavior of three metal alloys commonly used in water desalination plants was investigated using coupled multielectrode arrays consisting of aluminum-brass (HAl77-2), titanium alloy (TA2), and 316L stainless steel (316L SS). The three electrode types were coupled galvanically and arranged in different geometric configurations. Their corrosion behavior was characterized as a function of the chloride concentration. The potential and current distributions of the three-electrode coupling systems display electrochemical inhomogeneity. Generally, the aluminum-brass wires are anodic versus the titanium alloy and stainless steel. The titanium alloy acts as a primary cathode, and the 316L SS acts as a secondary cathode. The corrosion rate of aluminum-brass depends on the concentration of chloride ion, with a maximum corrosion rate at a chloride concentration of 2.3 wt %. In terms of geometrical arrangements, when the anodic HAl77-2 wires are located on the edge and are connected to the 316L SS wires in the coupling system, the main anodic area enlarges, especially in the area adjacent to the 316L SS wires. When the HAl77-2 wires are located between (in the middle of) the two other types of wires, the corrosion rates are higher than the corrosion rates observed from the other two geometrical arrangements

Elasto-magneto-electric (EME) sensors for force monitoring of prestressing tendons

Abstract Stress/force monitoring of prestressing tendons is challenging but crucial to the evaluation of the safety of structures in which they are used. To this end, a smart elasto-magneto-electric (EME) sensor based on elasto-magnetic (EM) and magneto-electric (ME) effects is proposed for noncontact field monitoring of the absolute stress in these steel tendons. In this paper, our research in design, implementation, and application of the EME sensory system for non-destructive monitoring of prestressing tendons is overviewed. The results confirm that the developed EME sensor possesses high repeatability, ease of operation and maintenance, corrosion resistance, and long expected service-life. It is demonstrated that the proposed EME sensory technology is feasible for the stress/force monitoring of prestressing tendons in both new and existing structures and the EME sensory system is reliable and stable