Precast Wall Panels Research Articles

Finite Element Assessment of Methods for Incorporating Axial Load Effects into Blast Design SDOF Analyses of Precast Wall Panels

AbstractInnovations in the U.S. construction and precast concrete manufacturing industries have resulted in efficient methods of constructing multistory buildings that are entirely supported by precast concrete walls (i.e., no structural frame). Simultaneously, the U.S. government has mandated overarching requirements and incentives that promote energy efficiency in all government buildings and facilities. The combination of construction efficiencies and relatively recent requirements for improving energy efficiency makes total precast construction an attractive option for constructing government, diplomatic and U.S. Department of Defense (DoD) buildings and facilities. However, to design load bearing wall panels for DoD blast response criteria, engineers need a relatively simple method for analyzing dynamic response under combined lateral and axial load effects. This paper presents methods for incorporating the P-delta and P-M interaction effects into the single-degree-of-freedom (SDOF) framework that is...

Theoretical and experimental study on precast reinforced concrete wall panels subjected to shear force

The paper presents the results of the first part of an experimental program developed to study the seismic performance of precast reinforced concrete wall panels with and without openings. The specimen characteristics and reinforcement configuration were taken from a typical Romanian project used widely since 1981 and scaled 1:1.2 due to the constraints imposed by the laboratory facilities. This type of precast wall panels was used mostly for residential buildings with multiple flats built from 1981 to 1989. The performance and failure mode of all of the panels tested revealed a shear type of failure that is influenced by the opening type, and critical areas and lack of reinforcement were observed in certain regions. A numerical analysis was performed to create a model that could predict the behaviour of the precast reinforced concrete shear walls of different parameters. The performed experimental tests stopped when the panels lost 20% of their load bearing capacity to be further repaired, strengthened post-damage and subsequently tested again. The precast reinforced concrete walls investigated in this study meet the requirements of Eurocode 8 for walls designed to DCM (medium ductility) as large, lightly reinforced walls.

Behaviour factor and displacement estimation of low-ductility precast wall system under seismic actions

This paper investigated the seismic behaviour of an innovated non-ductile precast concrete wall structural system; namely HC Precast System (HCPS). The system comprises load-bearing precast wall panels merely connected only to column at both ends. Such study is needed because there is limited research information available in design codes for such structure particularly in regions having low to moderate seismicity threats. Experimentally calibrated numerical model of the wall system was used to carry out nonlinear pushover analyses with various types of lateral loading patterns. Effects of laterally applied single point load (SPL), uniformly distributed load (UDL), modal distributed load (MDL) and triangular distributed load (TDL) onto global behaviour of HCPS were identified. Discussion was focused on structural performance such as ductility, deformability, and effective stiffness of the wall system. Thus, a new method for engineers to estimate the nonlinear deformation of HCPS through linear analysis was proposed.

Efficiency of Post-Tensioning in Seismic Retrofitting of Precast Cylindrical Concrete Reservoirs

Cylindrical concrete reservoirs are appropriate choice to store liquids such as water, oil, … etc. The use of pre-cast concrete reservoirs considerably increases the speed and precision of construction. In such reservoirs, the assembly of precast wall and roof panels is carried out in construction site. Nevertheless, because of weakness in connections between the wall panels and also between the wall and the foundation, seismic retrofitting may become essential. One innovative method that was applied for seismic retrofitting of numerous precast cylindrical water reservoirs in New Zealand included surrounding the reservoir wall by high tensile post-tensioning cables. In this paper, analytical modeling of wall and roof panels and post-tensioned cables is carried out using the finite element method to investigate the effect of post-tensioning force magnitude, liquid level in reservoir and position of post-tensioning cable on seismic response of reservoir for various height-to-diameter ratios of reservoirs with a constant volume.

High Performance Precast Wall Panels with Shear Transfer Provided by Carbon Fiber Grid

Composite insulated wall panels using carbon fiber grid in combination with expanded polystyrene (EPS) insulation have been produced for over 5 years. The carbon fiber grid and the EPS act together to provide shear transfer between the wythes of the composite panel. A design procedure has been developed, based on testing at Washington University and North Carolina State University. The approach discussed here is to ensure that the flexural strength, the cracking moment, and the deflection are all within acceptable limits. This paper first discusses the testing that has been performed to develop the material properties used in the design procedure. Then methods for computing the flexural strength, the cracking moment and the deflection are also presented. Deflections are not often an issue and cracking moments can be easily controlled by the amount of prestress. Therefore, the most important concern is providing adequate shear transfer. The design procedures discussed here were later verified by full scale testing at North Carolina State University.

Strengthening strategies using FRP composites for precast RC wall panels with cut-out openings

Abstract Building structures using Precast Reinforced Concrete Wall Panels (PRCWP) are widely used in Romania. An important disadvantage of these buildings is the functional rigidity of the interior space due to the dense distribution of the load bearing walls. Cut-out openings are often required to facilitate direct access from outside or between adjacent apartments. This paper presents a part of research program regarding the effectiveness of using the Externally Bonded Carbon Fiber Reinforced Polymer (CFRP-EBR) composites as seismic retrofitting solution for PRCWPs weakened by cut-out openings. The discussion was focused on the strengthening strategies adopted for both narrow and wide door openings.

Designing Concrete Precast External Wall Components on Multi Storey Steel Stuctures According to Modular Co-ordination

Lightweight curtain wall systems and precast concrete wall panels are commonly used in steel skeleton external wall construction. The design of external wall components must incorporate modular-dimensional coordination rules. Modular design of external walls reduces component types and increases the buildability of façades. The purpose of this study is to research the adaptability of large standard precast wall panels to steel skeleton structures according to the modular coordination rules. In addition, according to the possible locations of the wall panels in the façades, design dimensions are calculated and types of panels are recommended in conclusion.

Experimental Evaluation of the Composite Behavior of Precast Concrete Sandwich Wall Panels

Lateral load tests were performed on four full-scale precast concrete sandwich wall panels. The first panel was a typical precast, prestressed concrete sandwich panel that had shear transfer provided by regions of solid concrete in the insulation wythe, metal wythe connectors (M-ties), and bond between the concrete wythes and the insulation wythe. The degree of composite action developed by each shear transfer mechanism (regions of solid concrete, wythe connectors, and bond) was then evaluated by testing three additional panels that included only one mechanism each. The panels were tested in a horizontal position with simple supports under the action of a uniform lateral pressure. 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. 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.

CFRP Composite Connector for Concrete Members

Steel plate connections are frequently used in tilt-up and precast concrete building construction to tie adjacent wall panels together for shear and overturning effects, and to provide continuous diaphragm chord connections for wind and seismic loading. These welded connectors perform poorly in regions of high seismicity and are vulnerable to corrosion. Until now, retrofit and repair strategies for in-plane shear transfer strengthening were limited to attaching steel sections across panel edges. In the present paper, an experimental program is described that utilizes carbon fiber reinforced plastic (CFRP) composites to develop a viable retrofit scheme for precast concrete shear walls and diaphragms. Nine full-scale precast wall panel assemblies with CFRP composite connectors have been tested. The results show that the CFRP composite connection is an effective solution for the seismic retrofit and repair of precast concrete wall assemblies and other precast concrete elements, such as horizontal diaphragms, that require in-plane shear transfer strengthening.

Behavior of Welded Plate Connections in Precast Concrete Panels Under Simulated Seismic Loads

Tests were performed on precast wall panels with typical loose-plate connectors located in the vertical joint between panels. The tests were performed to investigate the performance of the connectors under simulated seismic loads. Inplane lateral cyclic loads were applied to the wall panels, which applied tension-shear and compression-shear forces to the loose-plate connectors. The paper describes the experimental program and results for the welded plate connections in ten precast concrete wall panel assemblies. Design assumptions and simplified design models are also examined. The research shows that the connection possesses little ductile capacity and, therefore, is not suitable for use in high seismic regions (Zones 3 and 4). However, based on the observed failure modes, minor modifications to the connection are suggested that will increase the ductility of the connection.

Ductility-based seismic design of precast concrete large panel buildings

Two approximate methods based on mechanism analysis suitable for seismic assessment/design of structural concrete are reviewed. The methods involve use of equal energy concept or equal displacement concept along with appropriate patterns of inelastic deformations to relate structure\'s maximum lateral displacement to member and plastic deformations. One of these methods (Clough\'s method), defined here as a ductility-based approach, is examined in detail and a modification for its improvement is suggested. The modification is based on estimation of maximum inelastic displacement using inelastic design response spectra (IDRS) as an alternative to using equal energy concept. The IDRS for demand displacement ductilities are developed for a single degree of freedom model subjected to several accelerograms as functions of response modification factor (R), damping ratios, and strain hardening. The suggested revised methodology involves estimation of R as the ratio of elastic strength demand to code level demand, and determination of design base shear using R-design less than or equal to R and maximum displacement, determination of plastic displacement using IDRS and subsequent local plastic deformations. The methodology is demonstrated for the case of a 10-story precast wall panel building.

Seismic Behavior and Design of Unbonded Post-Tensioned Precast Concrete Frames

Unbonded post-tensioned precast concrete walls are constructed by post-tensioning precast wall panels across horizontal joints using post-tensioning steel which is not bonded to the concrete. This paper describes an analytical investigation of the seismic behavior and design of these walls. Unbonded post-tensioned precast walls with strength and initial stiffness similar to monolithic cast-in-place concrete walls can be designed to soften and undergo large nonlinear lateral drift with little damage. The nonlinear behavior is primarily due to the opening of gaps along the horizontal joints. A performance-based seismic design approach is proposed in which the walls are required to resist design level ground motions with little damage and severe survival level ground motions with damage but without failure. Shear slip along the horizontal joints is prevented by design. Nonlinear dynamic analyses show that, compared to cast-in-place walls, unbonded post-tensioned precast walls undergo larger drift, but accumulate significantly smaller residual drift during an earthquake.

Structural analysis and design of the Metropolitan Water District Headquarters in Los Angeles, California

This paper presents important issues related to the structural analysis and design of a multistory office building in a zone of high seismicity. Designed in 1996, the Metropolitan Water District Headquarters Building is a concrete building located in downtown Los Angeles which occupies a spatial footprint of approximately 170 000 square feet. The structural system is a combination of cast-in-place and precast concrete framing and supports heavy, articulated precast wall panels. Plan irregularities and vertical setbacks have created a complex project which highlights the issues involved in contemporary design of tall buildings in southern California. As the building owner directed the design to meet the requirements of an essential facility, extensive linear and nonlinear analyses were performed to evaluate performance of the building during major earthquakes. © 1997 John Wiley & Sons, Ltd.

プレストレスを利用したプレキャスト耐震壁の開発

This precast system consists with precast columns, precast beams and precast shear wall panels that are combined between upper and lower beams using horizontal dry joints by prestressing. This panels are separated the precast columns. In conseguence, the system provides easy exchange of damaged panels in case of earthquake. To confirm the excution of this system, various models are tested whether the connection of prestressing bars exist or not, the windows of jacking space exist or not, the frames are damaged or not. The results shows that this system can be excuted with an ordinary management, and the damaged panels can be easily exchanged for new panels by adapting to the relative story displacement. Most of prestress transfered to the precast shear panels and didn't effect to the frame at the excution of new frame and the exchange of panels.

プレストレスを利用して梁に圧着した壁パネルの最大耐力

This paper deals with an experimental study on the strength of the precast wall panels, which are connected with the upper and lower beams using prestressing, not connected with the columns of the both sides. The experimental parameters are as follows ; magnitude of prestressing, sizes of openings in the center of the wall panel for fastening prestressed concrete (PC) steel bars, joining PC steel bars or not, filling the openings up with PC grout or not, etc. The maximum strength of the wall panel is investigated from some phases as follows; the shear resisting mechanism by cumulating truss mechanism and compressive strut of concrete, moment capacity of the parts sandwiched in the openings, and the slip strength of the horizontal joint published by the authors.

Horizontal Connections for Precast Concrete Shear Wall Panels Under Cyclic Shear Loading

The performance of precast concrete loadbearing shear wall panel structures during an earthquake relies on the behavior and integrity of the connections between the panels. Design of these structures requires the ability to predict the behavior of the connections. This paper presents results of an experimental study of horizontal connections for precast wall panels subjected to reversed cyclic shear deformations combined with simulated gravity loads normal to the connection. The influence of mild steel reinforcement, post tensioning and shear keys was investigated. Experimental results were used to determine the cyclic behavior of the connections and to identify the contribution of the connections and to identify the contribution of the connection components. Simple rational models were proposed to predict the limit states of the connections. Two numerical design examples are included to illustrate the proposed models. Based on the study, design recommendations are presented.

Behavior and Design of Shear Connections for Loadbearing Wall Panels

D inring the past decade, use of precast loadbearing shear wall panels for high rise construction has become very popular due to the high quality control achieved at the precast concrete manufacturing plant and the ease of panel assembly and erection at the project site (Fig. 1). In the structure, the precast panels are tied together using continuity reinforcement bars and mechanical shear connectors. The gap between the panels, which is required for alignment, is normally filled with a dry pack grout. This grouting system eliminates the use of falsework and minimizes the use of temporary supports. Current design sources'3 provide only limited information about the behavior and ultimate shear carrying capacity of the connections described in this paper. The information available in the literaturelo mainly describes the shear friction mechanism and the dowel action of initially cracked concrete to concrete surfaces. The results of such studies cannot be directly applicable to the predescribed connections due to the presence of the dry pack grout layer between the two concrete surfaces.

Structural Behavior of Prefabricated Shear Walls

In precast large-panel multistory buildings, prefabricated jointed panels form the shear wall to carry the lateral loads due to wind, etc. The in situ vertical and horizontal joints form slip surfaces and the interaction between the precast panels are provided by shearing action at the joints. In this paper, plane stress and interfacial finite elements have been used to represent the precast wall panels and the in situ joints. The effect of the in situ joint properties has been studied in depth as regards the overall flexibility and stresses in the prefabricated shear wall. It was observed that very stiff vertical joints between the panels makes the shear wall stiff like monolithic cantilever walls, whereas loosely jointed prefabricated walls are more flexible. It was also observed that the effect of horizontal joints at the floor levels is only marginal under normal circumstances. Failure load of a typical prefabricated shear wall has been determined from the nonlinear analysis of the wall assembly assum...

Wind Pressures on Open Rain Screen Walls: Place Air Canada

Wind pressure differences are measured across the rain screen and across the air barrier assembly of precast open rain screen wall panels. Twelve panels are instrumented mostly on the west, north, and east walls of the 24th floor of a 27-story office building in downtown Montreal. 32 channels were scanned at 30 times per second to allow reasonable resolution of peak gusts. However, some doubt remains about their spatial extent, as each 3.6 × 2.9 m (11.8 × 9.5 ft) panel had only one external tap. The maximum load measured on the rain screen in one year of continuous monitoring was 285 Pa (6 psf), of duration 1 second. The largest pressure difference across an entire panel of the building envelope never coincided with peak pressure differences on the rain screen. However, maxima due to wind only, across windward panels, ranged from 400–475 Pa (8.4–9.9 psf). Pressure differences across the air barrier assembly of wall panels included stack and HVAC effects of up to 150 Pa (3.1 psf) when outside temperatures dropped to -20°C (-4°F).

Minimum Reinforcement Requirements for Precast Wall Panels

Minimum Reinforcement Requirements for Precast Wall Panels