Behaviour of Partially Composite Precast Concrete Sandwich Panels Under Flexural and Axial Loads PDF Download

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ISBN:
Category :
Languages : en
Pages : 622

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Precast concrete sandwich panels are commonly used on building exteriors. They are typically composed of two concrete wythes that surround rigid insulation. They are advantageous as they provide both structural and thermal resistance. The structural response of sandwich panels is heavily influenced by shear connectors that link the wythes together. This thesis presents a study on partially composite non-prestressed precast concrete wall panels. Nine flexure tests were conducted on a wall design incorporating 'floating' concrete studs and Glass Fibre Reinforced Polymer (GFRP) connectors. The studs encapsulate and stiffen the connectors, reducing shear deformations. Ultimate loads increased from 58 to 80% that of a composite section as the connectors' reinforcement ratio increased from 2.6 to 9.8%. This design was optimized by reinforcing the studs and integrating them with the structural wythe; new connectors composed of angled steel or Basalt-FRP (BFRP) were used. The load-slip response of the new connector design was studied through 38 double shear push-through tests using various connector diameters and insertion angles. Larger connectors were stronger but more likely to pull out. Seven flexure tests were conducted on the new wall design reinforced with different combinations of steel and BFRP connectors and reinforcement. Composite action varied from 50 to 90% depending on connector and reinforcement material. Following this study, the axial-bending interaction curves were established for the new wall design using both BFRP and steel connectors and reinforcement. Eight panels were axially loaded to predesignated loads then loaded in flexure to failure. A technique is presented to experimentally determine the effective centroid of partially composite sections. Beyond the tension and compression-controlled failure regions of the interaction curve, a third region was observed in between, governed by connector failure.Theoretical models were developed for the bond-slip behaviour of the shear connection and to analyze the full panel's flexural and axial response to determine the longitudinal shear force transferred between wythes and account for partial composite behavior. The models were validated against experiments and used to conduct a parametric study. Among several interesting findings, the study demonstrated how composite action increases with the slenderness of axially loaded panels.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 310

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This study investigates two aspects of precast concrete insulated sandwich wall panels, namely mechanical connections and fatigue behaviour. In the first part, flexural tests were performed on panels with various end support conditions, loading orientations, and reinforcement and shear connector materials. Bolted angle connections were used to simulate practical support conditions, while loads were applied in a manner to simulate windward pressure as well as suction. Panels with steel and basalt fibre-reinforced polymer (BFRP) longitudinal reinforcement were tested and compared. Discrete steel and BFRP shear connectors were also used and evaluated. The bolted angle connections provided partial end fixity, thereby increasing the overall strength and stiffness relative to identical panels simply supported by rollers during testing. In all cases the bolted connections succeeded in developing the full strength of the sandwich panels. Panels with steel reinforcement failed due to rupturing of flexural reinforcement, while a panel with BFRP reinforcement failed due to rupturing of shear connectors and crushing of concrete in one wythe. Panels loaded in the direction of wind pressure achieved higher peak loads than identical panels loaded to simulate suction. An analytical model accounting for material nonlinearity, end support conditions and partial composite action from the shear transfer system was developed. The model accurately predicted flexural stiffness, while the peak load was underestimated in most cases. In the second part of the study, seven fatigue tests were performed on four panels with either steel or BFRP flexural reinforcement and shear connectors. Cyclic bending was conducted at two loading amplitudes: a high (Pdef) and a low (Pstr) load, representing serviceability limits for deflection and stress, respectively; both considerably higher than the maximum national wind load. The effect of a moderate axial load, as in loadbearing walls, was examined. The panels initially had a Degree of Composite Action (DCA) of 76-84%. The axially-loaded steel-reinforced panel achieved 1M cycles under Pstr, then another 1M under Pdef. Its DCA reduced to 73 then 65%. Without axial load, 1M and 0.24M cycles were achieved under Pstr and Pdef, and DCA reduced to 69 and 22%, respectively. The BFRP-panel failed at 0.07M cycles at Pstr. Its DCA reduced from 76 to 69%. It was then axially loaded and retested successfully to 1M cycles. Stiffness degradations of 12-50% consistent with DCA reductions were observed.

Author: Behnam Naji
Publisher:
ISBN:
Category : Concrete panels
Languages : en
Pages : 69

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Several experimental studies have shown the effect of core shear contribution in precast concrete sandwich wall panels. Due to the complex nature of such construction, quantifying the contribution of the core on the behavior of the precast concrete sandwich wall panel subjected to lateral load and in-plane loads is still a challenge. Based on engineering judgment and experience, current design practices assume a certain percentage in composite action between the faces (wythes) of the sandwich panel. In this study, a general equation for the deflection of a simply supported sandwich panel under in-plane and lateral loads was developed. The formulated equation includes all mechanical properties of the core and the thick similar faces. Methods for calculating bending moments and stresses to design the precast concrete sandwich wall panel were developed and validated. The proposed equations allow for parametric studies without limitations regarding reinforcements, core shear mechanical properties, and geometrical dimensions.

Author: Abdelfattah Elnur Abbaker
Publisher:
ISBN:
Category : Concrete panels
Languages : en
Pages : 252

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The sandwich panel is a layered structural system composed of a low density core material bonded to and acting integrally with, a relatively thin high strength facing materials held together by shear connectors. Core material usually act as insulation material t reduce the temperature inside the building. The bending action due eccentric load or lateral load is resisted by the tensile and compressive forces developed in outer layers while shear forces are resisted by the shear connectors. Sandwich panels are used as exterior walls in multi unit, resedential, commercial and ware house building, providing structural and thermal efficient building element. In this study, the structural behaviour of reinforced concrete sandwich wall panel has been investigated experimently in pre and post-cracking phase. Each panel consists of two outer reinforced concrete layers, interconnecyed together by different layout reinforced concrete ribs, which act as shear connectors. Three layers of shear connectors have been selected for the study; these are continuous vertical concrete ribs and truss type layout ribs inclined at 45 o and 67.5 o with the vertical. Finite element method has been used in analysis for comparison with the experimental test results in the pre-packing phase and to determine the stress distribution developed in the different components of the sandwich panel under different loading conditions. Six specimen of reinforced concrete sandwich panels (two identical specimens for each shear connector layout) each pf size 1200 x 2400 mm (width x height) have been cast in the laborotary and tested in vertical position under incremental vertical axial, lateral, and combined axial and lateral loading. The effect of different shear connector layout on the overall structural behaviour of the panel is highlighted. Moreover the composite behaviour of the sandwich panels, the percentage of load transferred to the ribs and the crack pettern have been investigated and discussed. The structural response of the sandwich panel in term of deflections have been found equal to 35 mm, 27 mm, 22 mm for panels typa A,B and C respectively. The lateral collapse load of the tested panels, have been found equal to 97 KN, 40 KN and 45 KN for panels type A, B and C respectively. From the results obtained in this study, it has been found that the sandwich panels with very vertical shear connector has a better overall structural response as reflected in the integrity of the sandwich wall panels system under action of combined axial and lateral loads, in comparison to sandwich panels with inclined layout connectors.

Author: fib Fédération internationale du béton
Publisher: FIB - Féd. Int. du Béton
ISBN: 2883941246
Category : Technology & Engineering
Languages : en
Pages : 146

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Book Description
During the mid-20th century, with the rise of industrial prefabrication, precast concrete sandwich panels started being used as cladding for buildings. Since then, society and construction industry have become increasingly aware of energy efficiency in all fields, including affordability and sustainability consciousness, while maintaining the buildings’ durability. As such, buildings have been subject to increasingly stringent requirements which has kept the technology of sandwich panels continually at the forefront of building envelope evolution. Nowadays, sandwich panels have reached the highest standards of functional performance and aesthetic appeal. In building construction, these sandwich panel attributes combine with the well-known advantages of prefabrication including structural efficiency, flexibility in use, speed of construction, quality consciousness, durability, and sustainability. Sandwich panels have gained more exposure, thus representing quite a significant application within the prefabrication industry and a vital component of the precast market. The fib Commission “Prefabrication” is eager to promote the development of all precast structural concrete products and to share the knowledge and experience gained, to aid with practical design and construction. By issuing this comprehensive overview, “Guide to Good Practice”, a better understanding of design considerations, structural analysis, building physics, use of materials, manufacturing methods, equipment usage and field performance will be provided. This document contains the latest information currently available worldwide. The Commission is particularly proud that this document is a result of close cooperation with PCI and that it is published by both the fib and PCI. This cooperation started six years ago, first with comparing the different approaches to several issues, then progressively integrating and producing common documents, like this one, that hasn’t yet been treated in a specific Guide by either body. This Guide is intended to be the reference document to all who are interested in utilising the advantages of Precast Sandwich wall panels. In conjunction with the previously published Planning and Design Handbook on Precast Building Structures, the designer will have significant resources to integrate sandwich wall panels into any applicable structure.

Author: Alper Ilki
Publisher: Springer Nature
ISBN: 3030881660
Category : Technology & Engineering
Languages : en
Pages : 2516

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This volume highlights the latest advances, innovations, and applications in the field of FRP composites and structures, as presented by leading international researchers and engineers at the 10th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering (CICE), held in Istanbul, Turkey on December 8-10, 2021. It covers a diverse range of topics such as All FRP structures; Bond and interfacial stresses; Concrete-filled FRP tubular members; Concrete structures reinforced or pre-stressed with FRP; Confinement; Design issues/guidelines; Durability and long-term performance; Fire, impact and blast loading; FRP as internal reinforcement; Hybrid structures of FRP and other materials; Materials and products; Seismic retrofit of structures; Strengthening of concrete, steel, masonry and timber structures; and Testing. The contributions, which were selected by means of a rigorous international peer-review process, present a wealth of exciting ideas that will open novel research directions and foster multidisciplinary collaboration among different specialists.

Author: Alexandar J. Mlynarczyk
Publisher:
ISBN:
Category : Concrete walls
Languages : en
Pages : 129

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Abstract: "To ensure sufficient composite action to meet structural strength and stiffness requirements in precast concrete sandwich wall panels, the designer must provide adequate shear transfer between concrete wythes. In a typical sandwich panel, shear transfer may be provided through several different mechanisms. These mechanisms include: (1) solid concrete regions; (2) mechanical connectors that pass through the insulation wythe; and, (3) bond between the concrete wythes and the insulation. The objective to the work presented in this report is to investigate the flexural behavior of sandwich panels and the contribution to composite action provided by regions of solid concrete, wythe connectors, and bond. Tests were performed on four full-scale precast sandwich wall panels. A Prototype panel was tested, which included regions of solid concrete in the insulation wythe, metal wythe connectors, and no attempt was made to disrupt the bond between the concrete wythes and the insulation wythe. The degree of composite action developed by each of the different shear transfer mechanisms was then evaluated by testing three additional panels that included only one mechanism of shear transfer (solid concrete, wythe connectors, or bond). It was found that, for the panel geometries and materials treated in this study, the solid concrete regions provide most of the strength and stiffness that contribute to composite behavior. Steel M-tie connectors and bond between the insulation and concrete contribute relatively little to composite behavior. Therefore, for design purposes, it is recommended that solid concrete regions be proportioned to provide all of the required composite action in a precast sandwich wall panel. A precast concrete sandwich wall panel constructed similarly to the Prototype panel treated in this study will behave as a fully composite panel in terms of service load-deflection behavior and flexural strength."

Author: Senthilkumar Krishnasamy
Publisher: CRC Press
ISBN: 1000531708
Category : Science
Languages : en
Pages : 400

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Book Description
A composite sandwich panel is a hybrid material made up of constituents such as a face sheet, a core, and adhesive film for bonding the face sheet and core together. Advances in materials have provided designers with several choices for developing sandwich structures with advanced functionalities. The selection of a material in the sandwich construction is based on the cost, availability, strength requirements, ease of manufacturing, machinability, and post-manufacturing process requirements. Sandwich Composites: Fabrication and Characterization provides insights into composite sandwich panels based on the material aspects, mechanical properties, defect characterization, and secondary processes after the fabrication, such as drilling and repair. FEATURES Outlines existing fabrication methods and various materials aspects Examines composite sandwich panels made of different face sheets and core materials Covers the response of composite sandwich panels to static and dynamic loads Describes parameters governing the drilling process and repair procedures Discusses the applications of composite sandwich panels in various fields Explores the role of 3D printing in the fabrication of composite sandwich panels Due to the wide scope of the topics covered, this book is suitable for researchers and scholars in the research and development of composite sandwich panels. This book can also be used as a reference by professionals and engineers interested in understanding the factors governing the material properties, material response, and the failure behavior under various mechanical loads.

Author: Manish Shrikhande
Publisher: Springer Nature
ISBN: 9819916089
Category : Science
Languages : en
Pages : 769

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Book Description
This book presents select proceedings of the 17th Symposium on Earthquake Engineering organized by the Department of Earthquake Engineering, Indian Institute of Technology Roorkee. The topics covered in the proceedings include engineering seismology and seismotectonics, earthquake hazard assessment, seismic microzonation and urban planning, dynamic properties of soils and ground response, ground improvement techniques for seismic hazards, computational soil dynamics, dynamic soil–structure interaction, codal provisions on earthquake-resistant design, seismic evaluation and retrofitting of structures, earthquake disaster mitigation and management, and many more. This book also discusses relevant issues related to earthquakes, such as human response and socioeconomic matters, post-earthquake rehabilitation, earthquake engineering education, public awareness, participation and enforcement of building safety laws, and earthquake prediction and early warning system. This book is a valuable reference for researchers and professionals working in the area of earthquake engineering.

Author: Akram Khan
Publisher:
ISBN:
Category : Plates (Engineering)
Languages : en
Pages : 250

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Book Description
This research investigates prefabricated light-gauge steel and concrete panels using reliable and commercially viable shear connectors. An analytical and experimental investigation was undertaken to study the flexural behaviour of light-gauge steel and concrete composite panels under uniform pressure. Normalweight and lightweight concrete panels were fabricated by embedding 16-gauge 41 mm x 203 mm steel channel sections (running parallel to each other) to a depth of 38 mm into a 64 mm thick concrete slab. Push-out tests were also conducted to evaluate the efficiency of three types of shear connection mechanism; natural surface bonding, predrilled holes, and punched holes. Only two types of shear connectors (predrilled holes and punched holes) were used in the full-scale panel specimens. Results show that the predrilled holes and punched holes provide full shear transfer between the steel and concrete. The ultimate load carrying capacity of the lightweight concrete panels exhibited similar behaviour to the normalweight concrete panels. All the panels exhibited good load carrying capacity and ductility, and satisfied the serviceability limit state of deflection. Thus, the proposed panels present a potential for a commercially viable composite floor system for building construction utilizing a maximum span of 2330 mm.