Concrete Infill Panels Research Articles

Cyclic Responses of Two-Side-Connected Precast-Reinforced Concrete Infill Panels with Different Slit Types

This study aimed to study the cyclic behavior of two-side-connected precast-reinforced concrete infill panel (RCIP). A total of four RCIP specimens with different slit types and height-to-span ratios modeled at a one-third scale were tested subjected to cyclic lateral loads. The failure mode, hysteretic behavior, lateral strength, stiffness degradation, ductility, and energy dissipation capacity of each RCIP specimen were determined and analyzed. The specimens experienced a similar damage process, which involved concrete cracking, steel rebar yielding, concrete crushing, and plastic hinge formation. All the specimens showed pinched hysteretic curves, resulting in a small energy dissipation capacity and a maximum equivalent viscous damping ratio lower than 0.2. The specimens with penetrated slits experienced ductile failure, in which flexural hinges developed at both slit wall ends. The application of penetrated slits decreased the initial stiffness and lateral load-bearing capacity of the RC panel but increased the deformation capacity, the average ultimate drift ratios ranged from 1.41% to 1.99%, and the lowest average ductility ratio reached 2.48. The specimens with high-strength concrete resulted in a small slip no more than 1 mm between the RC panel and steel beam, and the channel shear connectors ensured that the RC infill panel developed a reliable assembly with the surrounding steel components. However, specimens with concealed vertical slits (CVSs) and concealed hollow slits (CHSs) achieved significantly higher lateral stiffness and lateral strength values. Generally, the specimens exhibited two-stage mechanical features. The concrete in the CVSs and CHSs was crushed, and flexural plastic hinges developed at both ends of the slit walls during the second stage. With increasing concrete strength, the initial lateral stiffness and lateral strength values of the RCIP specimens increased. With an increasing height-to-span ratio, the lateral stiffness and strength of the RC panels with slits decreased, but the failure mode remained unchanged.

RCC frames with ferrocement and fiber reinforced concrete infill panels under reverse cyclic loading

An experimental investigation was carried out to study the strength and behavior of reinforced cement concrete (RCC) frames with ferrocement and fiber reinforced concrete infill panel. Seven numbers of 1/4th scaled down model of one bay-three storey frames were tested under reverse cyclic loading. Ferrocement infilled frames and fiber reinforced concrete infilled frames with varying volume fraction of reinforcement in infill panels viz; 0.20%, 0.30%, and 0.40% were tested and compared with the bare frame. The experimental results indicate that the strength, stiffness and energy dissipation capacity of infilled frames were considerably improved when compared with the bare frame. In the case of infilled frames with equal volume fraction of reinforcement in infill panels, the strength and stiffness of frames with fiber reinforced concrete infill panels were slightly higher than those with ferrocement infill panels. Increase in volume fraction of reinforcement in the infill panels exhibited only marginal improvement in the strength and behavior of the infilled frames.

FE Modeling of CFRP-Retrofitted RC Frames with Masonry Infill Walls

A number of numerical and experimental studies have been reported in recent literature to investigate the effects of infill walls on the seismic response of RC infilled frames. Many experimental studies used CFRP sheets as an external bracing system for retrofitting the infilled RC frames. It has been found that the common mode of failure of such retrofitted frames is the debonding of the CFRP-concrete adhesive material. In the current study, the behaviour of CFRP retrofitted infilled RC frames was investigated with a finite element micro model. In that model, a four-node shell element was used for modeling the concrete, infill panel and CFRP sheets. The interaction between concrete frame and infill panel was modelled using contact surfaces to allow the occurrence of separation and prevent penetration. Nonlinearities of the concrete, infill panel, steel and CFRP sheets were considered. To allow the occurrence of debonding mode of failure, the adhesive layer was modelled using cohesive surface-to-surface interaction model, which assumes that the failure of cohesive bond is characterized by progressive degradation of the cohesive stiffness, which is driven by a damage process based on the fracture energy. The proposed model was verified using experimental results from the literature. Results indicated that the cohesive model could capture the debonding mode of failure which has been observed experimentally. The validated micro model was used to investigate the effects of the strip end area, the anchor location and partial bonding of the CFRP sheet to the infill panel surface on the behaviour of infilled frames. The results of parametric study showed that, to get the highest efficiency of the CFRP retrofitted infilled frame, bonding about 25% only of the diagonal length from each end is sufficient to get the same behaviour of the totally bonded sheet.

Experimental Test and Non-Linear Finite Element Modeling Prediction on Profiled Steel Sheeting Dry Board (PSSDB) with Geopolymer Concrete Infill

Profiled steel sheeting dry board (PSSDB) system is made of profiled steel sheeting that is connected to the dry board using a self-drilling, self-tapping screw. This study aims to predicts the load-deflection behavior of PSSDB panel system under the influence of geopolymer concrete infill with finite element modeling. To achieve the target objective, the laboratory testing approach and a theoretical system behavior prediction are considered. Through a bending test, the stiffness of PSSDB full board with geopolymer concrete infill (FBGPC) panel is 27.42 kNm2 and the ultimate load is 13.13 kN/m2. The developed finite-element modeling (FEM) successfully predicts the behavior of PSSDB with geopolymer concrete infill panel with >85% accuracy.

Racking shear resistance of steel frames with corner connected precast concrete infill panels

When precast concrete infill panels are connected to steel frames at discrete locations, interaction at the structural interface is neither complete nor absent. The contribution of precast concrete infill panels to the lateral stiffness and strength of steel frames can be significant depending on the quality, quantity and location of the discrete interface connections. This paper presents preliminary experimental and finite element results of an investigation into the composite behaviour of a square steel frame with a precast concrete infill panel subject to lateral loading. The panel is connected at the corners to the ends of the top and bottom beams. The Frame-to-Panel-Connection, FPC4 between steel beam and concrete panel consists of two parts. A T-section with five achor bars welded to the top of the flange is cast in at the panel corner at a forty five degree angle. The triangularly shaped web of the T-section is reinforced against local buckling with a stiffener plate. The second part consists of a triangular gusset plate which is welded to the beam flange. Two bolts acting in shear connect the gusset plate to the web of the T-section. This way the connection can act in tension or compression. Experimental pull-out tests on individual connections allowed their load deflection characteristics to be established. A full scale experiment was performed on a one-storey one-bay 3 by 3 m infilled frame structure which was horizontally loaded at the top. With the characteristics of the frame-to-panel connections obtained from the experiments on individual connections, finite element analyses were performed on the infilled frame structures taking geometric and material non-linear behaviour of the structural components into account. The finite element model yields reasonably accurate results. This allows the model to be used for further parametric studies.

Seismic Retrofit of Steel Moment-Resisting Frames with High-Performance Fiber-Reinforced Concrete Infill Panels: Large-Scale Hybrid Simulation Experiments

AbstractRecent earthquakes around the world have demonstrated that steel moment-frame buildings designed based on older seismic provisions are seismically deficient. To enhance the seismic performance of these buildings, a new seismic retrofit system has been developed and evaluated experimentally as part of a two-story steel moment-resisting frame, designed in California in the 1980s. The proposed retrofit system consists of high-performance fiber-reinforced concrete (HPFRC) infill panels acting as energy dissipation elements that can be easily replaced after a major earthquake. Through two large-scale hybrid simulation tests of the retrofitted two-story steel moment-resisting frame, it is demonstrated that (1) the proposed retrofit system is effective in terms of reducing the maximum story drift ratios and residual deformations of the retrofitted steel moment resisting frame relative to the predicted bare frame performance, and (2) the structural damage of the retrofitted steel moment-resisting frame is...

Push-Pull Interface Connections in Steel Frames with Precast Concrete Infill Panels

This paper presents experimental and finite element results of investigations into the stiffness and strength of three discrete interface connections between simple steel frames and precast concrete infill panels serving as lateral bracing. The ability of the connections to resist compression and tension allows them to introduce substantial lateral stiffness and strength into so called semi-integral infilled frames.

Mechanical Model for Steel Frames with Discretely Connected Precast Concrete Infill Panels with Window Openings

This paper presents a mechanical model for a structure comprising of steel frames with discretely connected precast concrete infill panels having window openings, termed semi-integral infilled frames. The discrete panel-to-frame connections are realized by structural bolts acting under compression. The mechanical model enables analysing a building structure consisting of semi-integral infilled frames by standard structural analysis methods. Input for the model are geo- metrical and material properties of the frame structure and the structural characteristics of three types of springs represent- ing the frame joints, the panel-to-frame connections and the infill panel respectively. An overview of some of the research undertaken at Eindhoven University of Technology to study the behaviour of the springs representing the panel-to-frame connections is presented.Tests on individual components of the panel-to-frame connection were performed to establish load-displacement characteristics of the connection. A finite element model has been developed to investigate the structural behaviour of the components 'flanges in bending'combined with 'web in compression' by varying different parameters. The results of the research allow estimating the structural characteristics of the considered discrete panel-to-frame connection for different frame sections.

Cyclic Response of Precast High-Performance Fiber-Reinforced Concrete Infill Panels

Cyclic Response of Precast High-Performance Fiber-Reinforced Concrete Infill Panels

Experimental and numerical investigations into the composite behaviour of steel frames and precast concrete infill panels with window openings

As an alternative for conventional structures for tall buildings, a hybrid lateral load resisting structure has been designed, enabling the assembly of tall buildings directly from a truck. It consists of steel frames with discretely connected precast concrete infill panels provided with window openings. Besides the stiffening and strengthening effect of the infill panels on the frame structure, economical benefits may be derived from saving costs on materials and labour, and from reducing construction time. In order to develop design rules for this type of structure, the hybrid infilled frame has recently been subjected to experimental and numerical analyses. Ten full-scale tests were performed on one-storey, one-bay, 3 by 3 m infilled frame structures, having different window opening geometries. Subsequently, the response of the full-scale experiments was simulated with the finite element program DIANA. The finite element simulations were performed taking into account non-linear material characteristics and geometrical non-linearity. The experiments show that discretely connected precast concrete panels provided with a window opening, can significantly improve the performance of steel frames. A comparison between the full-scale experiments and simulations shows that the finite element models enable simulating the elastic and plastic behaviour of the hybrid infilled frame.

The collapse load for square concrete infill panels

A theoretical simulation of the tensile failure mode for concrete infill wall panels is presented. The iterative procedure is based upon an elemental idealisation of the panel and essentially it simulates cracking in the concrete by releasing nodes in the substitute structure. Series of panels, with and without cut-outs, have been analysed and the results are presented along with those obtained by experiment. The analysis therefore provides an estimate of the collapse load for a panel within the concept of limit state analysis referred to in the Draft Unified Code of Practice.