Precast Concrete Sandwich Wall Research Articles

Experimental study on non-load bearing multi-span sandwich wall panels for blast mitigation

Sandwich wall panels are known for their ability to provide resistance over a wide deformation range, rendering them suitable for blast resistance applications. These panels consist of layers of concrete with an insulating core, offering a structural solution with enhanced performance. Quasi-static testing was conducted on multi-span sandwich wall panels with intermediate connections to evaluate their behavior under controlled loading conditions. A total of twelve two-span details were examined and selected to match the standard designs employed in the Tilt-Up Construction (TCA) and Prestressed/Precast Concrete Industry (PCI). Among these details, three belonged to the TCA type with two duplicates, while the remaining two were representative of PCI designs with three duplicates. The results obtained from the quasi-static testing indicate that insulated sandwich wall panels possess sufficient deformation capability to meet the current blast response criteria. To assess the findings of the static experiments to the prevailing response limits, the outcomes were distilled into a multi-linear static resistance analysis. The findings support the use of insulated precast concrete (PC) sandwich wall panels, highlighting their suitability for blast-resistant designs within the constraints of current blast design limitations. Specimens with Halfen connectors showed 32 % higher energy absorption and a 58 % advantage over Stud connectors, making them superior for robust blast resistance applications.

Structural performance analysis of a new bolt–steel plate connection precast concrete sandwich wall structure

This study proposed a new low-rise bolt–steel plate connection precast concrete sandwich wall structure (PCSWS). Shake table testing was conducted on an experimental model of the bolt–steel plate connection PCSWS with two stories. The experimental phenomenon, failure pattern, displacement response, dynamic characteristics, and global hysteresis were analyzed in detail. The test results revealed that the proposed structure demonstrated excellent seismic performance without any structural cracks when subjected to an excitation intensity level of IX for Model-1. The seismic damage was moderate with no significant structural cracks after an excitation intensity level of IX for Model-2. Cracks in Model-2 occurred in the sequence of the places at the bottoms of the columns, the door corners, window opening corners, and the filled surfaces in the bolt–steel plate connection joint zone on the first floor. The observed damage states were primarily light and moderate, indicating the structure’s ability to withstand seismic events.

Improving sustainability of precast concrete sandwich wall panels through stone waste aggregates and supplementary

Precast concrete sandwich wall panels offer advantages such as design flexibility, ease of installation, cost-effectiveness, and energy efficiency due to the incorporated insulation layer, but regular concrete production has sustainability issues. This study aims to improve the sustainability of these panels by utilizing stone waste aggregates as a replacement for natural aggregates and supplementary cementitious materials as a partial replacement for cement. The panels were made with two concrete wythes reinforced with steel fibers and joined using basalt fiber-reinforced polymer (BFRP) connectors, with high-density expanded polystyrene (EPS) insulation (30 kg/m3) in between. Self-compacting concrete mixes with varying proportions of stone waste aggregates and supplementary cementitious materials were used. Full-scale wall panels were cast and subjected to flexural tests per ASTM standards, analyzing load-displacement curves, ultimate bearing capacity, and failure modes. The incorporation of steel fibers and stone waste aggregates resulted in substantial increases in failure load and flexural strength compared to controlled concrete panels, with the stone waste steel fiber panels exhibiting significantly higher maximum cracking loads and improved energy absorption and ductility. The inclusion of these sustainable materials, along with basalt fiber connectors and grooves in the EPS layer for mechanical interlock, prevented brittle failure modes and enhanced the composite action, leading to more ductile behavior under flexural loading. Utilizing sustainable materials like stone waste aggregates (100% replacement) and supplementary cementitious materials (30% replacement) in these panels can contribute to eco-friendly and efficient construction practices while maintaining adequate structural performance, paving the way for more sustainable building systems

Experimental and numerical investigations on the axial compression performance of precast geopolymer concrete sandwich wall panel

This paper investigated a novel precast concrete sandwich panel (PCSP) which made by the geopolymer concrete and enabled by the glass fiber reinforced polymer (GFRP) hexagonal tube connector. Six precast geopolymer concrete sandwich wall panel (PGCSP) specimens were fabricated and tested under axial compression load. The investigating parameters included the connector spacing, panel height, and panel thickness. The failure mode, axial load capacity, load-axial deflection relationship, and load-concrete strain relationship were studied and discussed. Moreover, two-dimensional (2D) finite-element (FE) analysis was conducted to reproduce the test. Parameter analysis was then performed to modify the axial load capacity formula in the Chinese code GB50010-2010. The results indicated that: all specimens exhibited large eccentric compression failure due to the second-order effect, which was caused by concrete crushing and horizontal cracking in the two wythes, respectively; with the decrease of the connector spacing, the crushing area of the specimens would be enlarged, the out-of-plane lateral deformation would be decreased, and the axial load capacity decreased by 17 % and 42 % when the connector spacing changed from 300 mm to 600 mm and 900 mm, respectively; with the decrease of the panel height and the increase of concrete wythes thickness, the axial load capacity of the specimens almost presented a linear increase; the established 2D FE model and the modified formula effectively reflected the axial load capacity of the specimens.

Optimization of Shear Resistance in Precast Concrete Sandwich Wall Panels Using an S-Type Shear Connector

Precast concrete sandwich wall panels (PCSPs) are popular for building exteriors due to their high thermal efficiency, composite performance, and low manufacturing and maintenance costs. Researchers have investigated the possibility of reducing the panel thickness while maintaining the cladding components’ thermal efficiency and strength to further improve efficiency and to reduce material consumption. However, limited research has been conducted on the shear bonding of steel plates, which is critical to ensuring durability and energy efficiency. This study investigated the shear behaviour of PCSPs with an S-type shear connector (SSC) through nine push-off tests and non-linear finite element modelling using Abaqus. Parametric studies were carried out to investigate the influence of the geometric properties of the SSC, the yield strength of the steel and the insulation thickness. The results suggest that the maximum secant stiffness for SSCs was achieved at a width of 101.4 mm and a thickness of 2 mm. Therefore, it is recommended that the width of the SSCs be limited to this value or less. Furthermore, the study found that increasing the yield strength of the steel beyond a thickness of 2 mm and a width of 101.4 mm did not improve the results and had a negative impact on the secant stiffness of the SSCs.

Seismic performance of precast concrete sandwich walls with bolt-steel plate connection

The bolt-steel plate connection stands as a dry connection method in precast structures characterized by its simplicity, high efficiency, ease of assembly and disassembly, and environmental protection. Five precast concrete sandwich walls (PCSWs) with glass fiber-reinforced polymer (GFRP) to connect the interior and exterior concrete wythes were designed and tested to investigate the seismic performance of such walls under cyclic loads. Ultra-high performance concrete (UHPC) was used to strengthen the bolt-steel plate connection joint. This study investigated the effect of the sandwich wall between the two bolt-steel plate connection joints, opening, and UHPC on the seismic performance of PCSWs. The findings revealed that the sandwich wall between the two bolt-steel plate connection joints, UHPC, and the interface between UHPC and ordinary concrete had a significant influence on the failure modes, including four failure modes: shear failure of bolt-steel plate connection joint, concrete crushing at the wall toe and through-crack of the shear oblique cracks and horizontal joint, shear failure at the interface between the solid and sandwich walls, and shear failure typified by a "Keyway" configuration. The use of UHPC to strengthen the bolt-steel plate connection area could significantly improve the load-bearing capacity and peak drift ratio. Whether the sandwich wall was used in the non-bolt-steel plate connection area in the horizontal joint zone had minimal influence on both the load-bearing capacity and peak drift ratio. For the walls without UHPC strengthening, the ultimate load and ultimate drift ratio could be increased by using the sandwich wall between the two bolt-steel plate connection areas, however, it was the opposite when UHPC strengthening was used. The paper also compared the sandwich walls with the solid walls, and the results showed that the sandwich wall with bolt-steel plate connections had good seismic performance.

Experimental and theoretical study on seismic behavior of a new UHPFRC sandwich wall and wall-wall joint

A new type of precast ultra-high performance concrete (UHPFRC) sandwich wall is proposed in this study. The proposed UHPFRC sandwich wall is composed of the UHPFRC layers, extruded polystyrene foam (XPS) board layer, and short UHPFRC columns connecting the UHPFRC layers. Compared with the traditional reinforced concrete wall, the UHPFRC sandwich wall possesses lower self-weight, less reinforcement, and higher strength. In addition, two types of wall-wall vertical joint connection methods, flexible cable connection and embedded steel plate welding connection, are proposed. The pseudo-static tests on five UHPFRC sandwich wall specimens were conducted to study the effects of UHPFRC layer thickness, reinforcement ratio, and width of edge solid area on the seismic behavior of the wall. Then, the seismic performance of different connection methods was studied by pseudo-static tests on two T-shaped UHPFRC sandwich wall-wall joint specimens. Test results demonstrate that the unreinforced UHPFRC sandwich wall, with 20–30 mm UHPFRC thickness and 150 mm edge solid area, showed excellent cracking resistance and seismic behavior. The cracking loads are more than 50% of the peak loads, and the bottom shear capacity to self-weight ratios are generally more than 35. The seismic behavior of the wall-wall joints connected by the flexible cable and embedded steel plate welding are both reliable. Finally, formulas for cracking and peak load of the UHPFRC sandwich wall are proposed and the fiber model is developed for analysis of the wall-wall joint, which is verified by the test results to be accurate and reasonable.

Development of Sustainable Precast Concrete Sandwich Wall Panels using artificial aggregates and mineral admixture

Development of Sustainable Precast Concrete Sandwich Wall Panels using artificial aggregates and mineral admixture

Thermal performance and reduced carbon footprint of precast concrete sandwich wall panels (PCSWPs) with composite shear connector – an experimental assessment

ABSTRACT The objective of the present work is to compare the thermal performance of precast-reinforced sandwich wall panels to that of precast-reinforced concrete wall panels. The variables used in this investigation are two different insulation materials (expanded polystyrene (EPS) and extruded polystyrene (XPS) and three different connectors (steel, glass fiber (GFRP)-wrapped steel, and aramid fiber (AFRP)-wrapped steel). A thermal analyzer setup was developed to investigate the heat transfer between the exterior and interior of the panels. The results showed that sandwich wall panels had better thermal resistance compared to the precast concrete wall panel. The temperature on the interior surface of the control specimen was 44°C after the stipulated test period. According to the experimental findings, inclusion of the insulation layer (no connectors) reduced heat transfer by 7.4°C for XPS and 6.7°C for EPS. The temperature on the interior surface was reduced only by 1.6°C and 3.6°C for sandwich panels with steel shear connectors and EPS and XPS as insulation material, respectively, indicating thermal bridging. Diminution of temperature on the interior surface of the sandwich panels with FRP-wrapped connectors varied between 5°C and 7.1°C compared to control specimen as the corrugated C-type fiber-wrapped shear connectors significantly decreased the thermal bridge between layers. In sandwich wall specimens, CO2 emissions from concrete were decreased up to 33%. Embodied carbon during the manufacturing of these panels was also compared, and it was found that the carbon emission was reduced up to 21% in the precast sandwich panels when compared to the precast reinforced wall panels.

Shear Transfer Mechanism between CFRP Grid and EPS Rigid Foam Insulation of Precast Concrete Sandwich Panels

An experimental program was implemented to investigate the shear transfer mechanism of carbon-fiber-reinforced polymer (CFRP) grids and expanded polystyrene (EPS) rigid foam insulation in three wythe precast concrete sandwich wall panels. The purpose of the research was to measure the shear flow capacity and to observe the failure mode(s) of precast concrete sandwich panels manufactured with a CFRP grid shear transfer mechanism between wythes. Six precast concrete sandwich panels were examined by push-out tests in which the center concrete wythe was pushed downward with respect to two outer concrete wythes. It was observed that the average shear flow capacity of the specimens having 2 in (51 mm) thick foam was higher than that of the specimens having 4 in (102 mm) thick foam. In addition, stiffness decreased significantly when the thickness of the EPS insulation increased. The failure mode for the panels included relative displacement between the center concrete wythe and the outer concrete wythes. Test results showed that panels tended to fail by CFRP grid rupture, CFRP grid pull-out, and loss of bond at the concrete/foam interface. Further tests should be performed to fully comprehend the nature of the shear transfer mechanism between the specific CFRP grid used and EPS rigid foam insulation.

Shaking table tests and seismic assessment of a full-scale precast concrete sandwich wall panel structure with bolt connections

A novel, light-weight, sustainable, repairable and cost-effective precast concrete sandwich wall panel structure system is proposed in this paper, including the dry bolt connections and the precast concrete sandwich panels. To evaluate the seismic performance of precast structure system, a sequence of shaking table tests is carried on the full-scale precast concrete sandwich wall panel structure, and the dynamic characteristics, damage pattern, dynamic responses and seismic fragility are investigated and analyzed by the test results under service level earthquake, design based earthquake, and maximum considered earthquake. The seismic fragility curves and failure probability curves are analyzed by the shaking table test results, which quantitatively describes the seismic performanceexpressed by probability. The results show that the precast concrete sandwich wall panel structure performs high lateral stiffness, large safety margins and high strength reserves. The precast concrete sandwich wall panel structure system presents a good seismic performance. The damage of the structure is slight under maximum considered earthquakes, and the structure has begun to enter the plastic stage. The light-weight characteristic reduces the dynamic responses, and the mild sliding between precast components consumes a fraction of seismic energy.

Theoretical, experimental and numerical study on the influence of connectors on the thermal performance of precast concrete sandwich walls

The thermal performance of precast concrete sandwich walls is in direct relation to energy efficiency of prefabricated buildings. This paper presents the theoretical, experimental and numerical studies on the thermal performance of precast concrete sandwich walls. The equivalent heat transfer coefficient model was proposed by theoretical analysis, and verified by experimental and numerical study. Six specimens with three types of connectors were fabricated, tested and modeled. The theoretical, experimental and numerical results agreed well, the accuracy of the equivalent heat transfer coefficient model was verified. It revealed how the material and geometrical parameters of connectors influenced the thermal performance of walls. The results showed that as the thickness of insulation increased from 30 mm to 90 mm, the heat transfer coefficient decreased by about 56.8%, 58.8% and 59.9% for theoretical, experimental and numerical results respectively. Meanwhile, an increased spacing and decreased connector length led to a better thermal performance, which further indicated the necessity to research the impact on thermal performance caused by connectors. It was also found that the proposed model was more suitable for the walls with stainless steel connector in this paper, for the walls with low thermal conductivity of connector like GFRP connector, the equivalent heat transfer coefficient could be obtained based on a prediction model of thermal bridge influence area and revised by correction factor in further research.

Influence of alkali-resistant glass fiber on seismic performance of precast ceramsite concrete sandwich wall panels

Shear wall, which is a component commonly used in high-rise building to resist the side force, has been widely applied in earthquake-prone regions. In this paper, a new type of prefabricated alkali-resistant glass fiber ceramsite concrete sandwich composite shear wallboard is proposed, which is composed of the polystyrene insulation board set in the middle and the alkali-resistant glass fiber ceramsite concrete boards set at both sides. This type of sandwich composite shear wallboard solves multiple problems of ordinary wallboard insulation materials from the perspective of structural form, including hidden risks of fire and peeling-off. Research experience shows that alkali-resistant glass fiber has high tensile, bending, crack, impact and alkali resistance, so adding the alkali-resistant glass fiber into concrete can improve its strength, toughness, crack resistance and corrosion resistance. Due to the existence of fiber, the cracks of cracked wallboard will open and close repeatedly under low reversed cyclic loading, so it can effectively absorb more seismic energy. Besides, the ceramsite concrete is featured in comparatively small elastic modulus and light mass, which help to reduce the dead weight of the wallboard. In a word, this kind of wallboard can effectively weaken the impacts of earthquake force and improve the overall seismic performance of wallboard structure. Therefore, in this paper, three types of specimens are designed with different admixture volumes of alkali-resistant glass fiber, respectively: 0%, 0.3%, and 0.4%. Through the experimental study on the seismic performance of the specimens, the influence law of different alkali-resistant glass fiber content on the seismic performance of the specimens is obtained. The study results show: compared with ordinary wallboard, the cracking displacement of the specimens with 0.3% and 0.4% fiber admixtures are improved by 42.63% and 35.79% respectively. This indicates that the fiber can delay the cracking of the test piece and improve the functional coordination among various materials, thereby easing the deformation of the overall wallboard when bearing forces. When the admixture amount of fiber reaches 0.3%, the specimen shows excellent performance in various seismic indicators, such as hysteresis, ductility, and energy consumption, presenting good application prospects. However excessive fiber admixture in ceramsite concrete actually has no good effect on the overall performance improvement of the wallboard. Therefore, in practical construction, this type of fiber shall not be added randomly.

Axial-flexural behavior of FRP grid-reinforced geopolymer concrete sandwich wall panels enabled with FRP connectors

This paper presents experimental and theoretical investigations conducted on a novel precast concrete sandwich wall panel (SWP) subjected to eccentric axial loading. The proposed SWP is composed of geopolymer concrete wythes which were embedded with basalt fiber reinforced polymer (FRP) bars/grids. Hollow Glass FRP (GFRP) tubes were used as connectors. Nine such SWPs were prefabricated and tested. The key design test parameters considered were slenderness ratio of the SWP, load eccentricity, and type of longitudinal reinforcement (FRP bar or grid) in wythes. The failure modes, load-deformation behavior, and load-strain behavior were studied and reported. It was found that the axial load capacities of the eccentrically loaded SWPs subject to load eccentricity-to-sectional thickness ratios of 0.15, 0.45, and 0.63 were reduced by 35%, 75%, and 85% (average of the load capacity values for the slender and squat SWPs), respectively, compared to their counterpart concentrically loaded SWPs. A second-order theoretical analysis was also conducted to obtain the axial load-moment interaction curves of equivalently assumed sections, and the outcomes were compared with the experimental ones to validate the modeling.

Structural behavior of FRP grid reinforced geopolymer concrete sandwich wall panels subjected to concentric axial loading

A new type of precast concrete sandwich wall panel, consisting of two basalt fiber reinforced polymer (FRP) reinforced geopolymer concrete wythes and an insulation layer, which are connected with hollow tubular glass FRP connectors, is studied in this paper. Ten sandwich wall panels were prefabricated and subjected to concentric axial loading. The primary test variables included slenderness ratio of the wall panel (i.e., the effective height to total sectional thickness ratio), longitudinal spacing of connectors, and the ratio of the wythe thickness to the insulation layer thickness of the wall panel. The load–deflection relationships, failure modes, and load–strain relationships were carefully investigated. All the wall panels failed by crushing of concrete. The connectors were subjected to axial force, transverse shear and bending in order to allow two wythes to deform together. The axial load capacity of the wall panel was reduced by 26% as the slenderness ratio varied from 8 to 17. The spacing of FRP connectors was found to have a marginal impact on the axial load capacity because of the existence of capping beams at the end of panels. An increase in the insulation thickness while keeping the wythe thickness constant resulted in a significant rise in the ultimate axial load in the case of panels having a higher slenderness ratio. A theoretical second-order analysis was performed to predict the ultimate axial load of equivalently assumed solid wall panels, and the predicted results were compared with the experimental ones.

High Temperature Performance of a prefabricated concrete sandwich panel

The innovative sandwich wall panel studied in this paper can be used as the load-bearing member of the structure. In addition to the traditional sandwich panel structure, the new panel system also has the characteristics of spiral stirrups along the section of the core column, 650mm column spacing, foam concrete for insulation layer and self-compacting concrete for outer layer. In addition, in order to improve the overall strength and stiffness of the panel, a unique wire system consisting of two vertical wire mesh connected by a short horizontal steel bar is adopted in the concrete layer. In order to study the mechanical properties of the new panel system at high temperature, ABAQUS simulation was carried out. The simulation results show that the new precast concrete sandwich wall system has good resistance to high temperature and still has good bearing capacity after high temperature.

Review of thermal and environmental performance of prefabricated buildings: Implications to emission reductions in China

Prefabricated buildings recently became more prominent providing significant benefits including contribution to emission reductions at scale and the manufacturing of building components to high accuracy. However, in China, the proportion of prefabrication is lower than that in many developed countries. The prefabricated wall is one of the most important precast elements and its thermal performance has significant impacts on buildings' energy consumption and environmental performance. This work reviews the thermal performance of prefabricated walls encompassing survey of two common structures, precast concrete sandwich walls and lightweight steel-framed walls. The applicability and limitations of methods frequently used to determine the thermal resistances of these two walls are presented. This article also shows a literature review on the implications of prefabricated buildings to China's emission reductions. Compared to conventional buildings, the contribution of prefabricated buildings on China's emission reduction has been recognized. The potentials on building energy efficient and waste minimisation were also acknowledged. It is concluded that the prefabrication has been generally considered to be a more sustainable method in building sector. The energy-saving potential of prefabrication was demonstrated based on life cycle analysis and thermal performance evaluation. It was found the thermal performance of buildings has multiplied by adopting prefabricated façade elements for building retrofitting. More studies related to thermal performance of prefabricated walls with different structures shall be covered in future research. It is also suggested to develop a more representative result of energy performance by adopting prefabrication, with all dimensions of prefabricated buildings' feature considered.

Experimental and Numerical Investigation of Novel I-Shaped GFRP Connectors for Insulated Precast Concrete Sandwich Wall Panels

Abstract Insulated precast concrete sandwich wall panels (IPCSWPs) are widely used in the thermal resistance systems of buildings. This paper proposes a novel I-shaped glass fiber-reinforced plasti...

A comparative study of different methods to calculate degrees of composite action for insulated concrete sandwich panels

Precast concrete sandwich wall panels consist of two outer wythes of precast concrete separated by a middle layer of insulation. In recent years, Fiber-Reinforced Polymer (FRP) shear connectors have been increasingly used since they have lower thermal conductivity compared to traditional steel shear connectors, which can significantly reduce thermal bridging. However, FRP shear connectors have lower stiffness, resulting in partial Degree of Composite Action (DCA), which is an important parameter to describe the structural behavior of the panels. Different methods have been proposed to calculate DCAs, including displacement method, strain method, and load method. This paper will compare and evaluate the effectiveness of these methods. A bending test was conducted on a full size of 7 m × 3 m, precast, prestressed insulated concrete sandwich panel with FRP shear connectors. A non-linear Finite Element (FE) model is created, where good correlations can be achieved between the test and FE results. The FE model is further employed to conduct a parametric study by varying the stiffness of the shear connectors. DCAs for different stiffnesses are calculated using the aforementioned three methods and the applicability and limitation of each method are investigated.

Experimental and numerical studies on the lateral performance of concrete sandwich walls

SummaryA series of quasi‐static tests was presented to study the lateral behavior of concrete sandwich walls and the precast concrete sandwich walls; the finite element analysis (FEA) models were built for numerical simulation of the specimens, and the parameters affecting the seismic performance of sandwich walls, and the precast sandwich walls were also analyzed based on the FEA models. The results show that the shear failure occurs in regular squat shear wall; the setting of the foam plate effectively reduces the stiffness and load capacity, and the reasonable design of sandwich region is conducive to the seismic performance. The responses obtained by the FEA models match well with the experimental results. The stiffness and load capacity of sandwich wall are increased, but the ductility is reduced when the axial load is increased; the deformation capacity can be greatly improved by increasing the aspect ratio but at the cost of load capacity and stiffness; the reasonable match of load capacity, stiffness, and ductility can be achieved by maintaining the appropriate length and thickness of the foam plate. The greater the friction force of CAF in the vertical seam of precast sandwich wall, the greater the load capacity and initial stiffness and the stronger the integrity of the jointed wall. When the strength of SRS in the horizontal seam is small, the concrete sandwich wall basically maintains elasticity; the deformation is mainly concentrated on SRS; when the strength of SRS is too large, SRS do not yield or the yield displacement is large, and the load capacity is mainly affected by the concrete sandwich wall.