Double-tee Beams Research Articles

A component method approach for single-sided beam-to-column joints with CHS column and welded double-tee beam

This paper focuses on predicting the flexural stiffness and strength of beam-to-column joints with Circular-Hollow-Section (CHS) columns and externally welded double-tee beams using the Component Method approach. Currently, Eurocode 3 Part 1.8 lacks guidelines for assessing the stiffness of these joints, resulting in their practical modelling using extreme assumptions like pin or full restraint. Nevertheless, the literature demonstrates that these joints can exhibit semi-rigid behaviour due to the relatively high local deformability of the tube in the joint area. Another concern relates to the strength of these joints. In fact, recent studies have shown that Eurocode 3 Part 1.8 formula for predicting the yield resistance of these joints is over-conservative.Within this framework, the purpose of this study is to fill the current knowledge gaps (over-conservative strength prediction and lack of rules for determining the stiffness) by undertaking a thorough investigation involving numerical and analytical activities. Specifically, the research presents a component-based modelling approach for predicting stiffness and strength of CHS to double-tee beam connections.In this regard, the work presented in this paper has involved the selection of experimental tests from literature to validate a Finite Element (FE) model, specifically focusing on X- and T-joints and internal and external beam-to-column joints. The validated numerical models have been then employed to simulate the response under monotonic loading conditions of additional sets comprising forty T-joints and thirty external beam-to-column joints, respectively. The currently available formulations for predicting the resistance of T-joints were applied to the forty cases simulated, evaluating their accuracy. This allowed the individuation of the most accurate literature formula for the strength prediction of T-joints, showing that the recent proposal of Voth and Packer (2012) yields sufficiently accurate results. Instead, analytical formulations for predicting the stiffness of T-joints were properly derived in a closed-form solution and were validated against the results of the parametric study. Finally, drawing upon knowledge regarding the stiffness and strength of T-joints, the flexural response of external beam-to-columns connections was evaluated proposing a component model, whose accuracy was verified against the cases simulated in the parametric analysis.

Mechanical Modelling of the Strength and Stiffness of Circular Hollow Section Tube under Localised Transverse Compression and Tension

The component method is a powerful tool for designing and modelling steel beam-to-column connections. Its widespread use is ensured by several formulations currently included in Eurocode 3 part 1.8 for welded and bolted joints. However, the recent use of 3D Laser Cutting Technology (3D-LCT) in the construction market has enlarged the range of solutions, allowing the realisation of tubular columns with passing-through elements. Given the recent development, no design formulations are currently provided for this typology. At this moment, only a few research studies have developed to fill this knowledge gap. At the University of Salerno, since some years, research efforts are ongoing to characterise the flexural strength of connections between Circular Hollow Section columns and passing double-tee beams, suggesting methodologies to predict the behaviour of the resistance and stiffness of this typology and some of its elementary joint components. Within this framework, this paper aims to examine the strength and stiffness of one of the main components of this joint, which was never examined previously, that is the so-called tube under localised transverse tension/compression. Design formulations are derived from a parametric study carried out through numerical simulations of several geometric configurations.

Shear behavior of full-scale prestressed concrete double tee beams with steel-wire meshes

Prestressed concrete double tee (PCDT) members have been widely used in parking buildings with large spans and heavy loads. To investigate the shear behavior of PCDT members, four full-scale PCDT members with steel-wire meshes were tested under monotonic loading in this paper. The two beam-end zones of each specimen were loaded to failure. The parameters studied in-depth were the ratio of the shear span to the effective depth λ and the area of prestressing steel strands. The failure modes, the strain of concrete and steel bars, shear force-deflection curves, cracking load, and shear strength were discussed in detail. The test results show that the variation of the ratio of the shear span to the effective depth λ and the area of prestressing steel strands have a significant effect on the inclined crack distribution of the PCDT members. The deformation capacity of PCDT members increases with an increase in the ratio of shear span to effective depth λ and the area of prestressing steel strands. The shear strength decreases with an increase in the ratio of shear span to effective depth λ and increases with an increase in the area of prestressing steel strands. PCDT members have good crack closure performance and deformation recovery ability after removing the load. Furthermore, an analytical model was proposed to predict the shear strength of PCDT members, which considers the effect of the ratio of shear span to effective depth λ, steel-wire meshes, prestressing steel strands, and the flanges of beams. For an analytical model, the key parameters of the shear-compression zone were established based on the cross-section strain analysis and Rankine's failure criterion. The calculation results show that the proposed model can accurately predict the shear strength of PCDT members. The average predicted-to-test shear strength ratio and the integral absolute error are 0.989 and 0.071, respectively.

Prediction of Shear Capacity of Flange-to-Flange Connectors of Double-Tee Beams Under Static and Cyclic Loading Conditions

Prediction of Shear Capacity of Flange-to-Flange Connectors of Double-Tee Beams Under Static and Cyclic Loading Conditions

Optimal parameter area for steel corrugated web beams

The optimal application area of steel corrugated web beams is considered. The optimal height for beams with the set moment ofresistance is calculated and spans for such beams isdetermined. The problem takes into account thepeculiarities of the actual operation of the corrugated web. The parameter region is located within the area of rigidity constraints and manufacturing constraints. Actual work features of a corrugatedweb are considered. The mathematical beam modelis constructed as a problem of minimizing the objective function (mass of the beam) with structural coefficients. The parameters of the structural model correspond to Zenam technology. The designlimitations of this task depend on the beam technology of manufacturing. The physical model is a double-tee beam of the 1st class according to thestress-strain state (in accordance with DBN V.2.6- 198). Shear strength constraints of the web and the loss web stability constraints are taken into account. The value of the optimal beam height underthe condition of permissible deflection is considered and the thin web shear deformation is taken into account.The dependences are obtained and a simple method is constructed, which allows analyzing the optimal beam parameters in height and effective design parameters. The method makes it possibleto install rational solutions for the planning of coatings and floors using corrugated beams. An example of determining the range of optimal parameters within the range of rigidity constraints and technological constraints is given.It is shown that the study of beams with sinusoidal-corrugated walls should be carried out taking into account the real conditions of operation and reconstruction, ensuring technological requirements and fire resistance requirements in the future.

Full-Scale Experimental Verification of UHPC-RC Composite Slab Culvert with a Clear Span of 8 m

To enhance the structural performance and durability of a conventional reinforced concrete (RC) cover slab over a culvert as well as to improve its spanning ability, this paper presents a novel ultrahigh-performance concrete (UHPC)-RC composite cover slab with a clear span of 8 m. The inverted prefabricated UHPC single-Tee or double-Tee beam was placed at the bottom of the cast-in-place normal strength concrete to form the UHPC-RC composite cover slab. A full-scale experimental test on the UHPC-RC composite cover slab was conducted to explore and quantify its mechanical performance. The structural characteristics of the slab, such as failure mode, moment capacity, flexural stiffness, concrete strain distribution, and cracking behavior, were experimentally investigated. The results indicated that, compared to the conventional RC cover slab, the UHPC-RC composite cover slab exhibits a typical flexural failure with a higher cracking resistance, flexural stiffness, flexural capacity, and ability to restrain the propagation of the cracks. An optimized scheme is successfully applied to the practical project. Field testing during the construction process was conducted to investigate the flexural performance of the new composite structure. The results indicated that the structural behavior of the UHPC-RC cover slab aligned well with its predicted values, demonstrating the effectiveness and feasibility of using the UHPC-RC composite cover slab in practical engineering applications.

Design Aids for Prestressed Concrete Double Tee Beam with Web Opening Associated With the Variation of Its Compressive Strength

Precast prestressed concrete double tee beams are one of the most popular precast concrete floor framing system, which it’s being from necessity to carry out many researche’s studies to predict a powerful tool to simulate its full behavior. Herein, an investigating studies have been carried out to check the validity of increasing span length by increasing concrete compressive strength with the existence of web opening. The main advantage of these openings is that mechanical equipment can pass through the webs of double tees instead of under them. This reduces the floor-to- floor height and the overall cost of the building. Another advantage is a slight reduction in double tee weight that would improve the demand on the supporting frame both under gravity loading and seismic excitation. All of that advantage will be more benefit with larger span length, that will be limited within the existence of web opening. A numerical model was prepared checked to simulate the nonlinear behavior of prestressed concrete beams under monotonically increasing load. Within such numerical model, tested programs were made to predict longer span in considerable concrete compressive strength, that chosen from practical available values can be achieved in the site. After all of that a design charts were prepared to be a guide tool to engineers when double tee beams with web opening required to cover more span length. Curves are classified and presented considering the most common typical sections of the double tee beams modified to show the flexibility could be obtained when changing concrete compressive strength.

On-Site Acoustic-Emission Monitoring for Assessment of a Prestressed Concrete Double-Tee-Beam Bridge without Plans

AbstractAcoustic emission was used in this study to assess the condition of a simple-span, prestressed concrete bridge located in southern New Mexico during a proof test. The 40-year-old bridge is county owned and no design plans were available. Acoustic emission (AE) data were collected under several loading conditions from two groups of sensors placed near the support and midspan of an interior double-tee beam. Strain measurements were also taken at midspan and used to direct the test and determine the maximum loading. AE data analysis methods were applied to evaluate the response of the structure under increasing loads and to develop crack maps. Analysis of the AE data showed signs of internal beam microcrack development near the supports (shear region) as well as in the midspan (moment region). The AE data indicated that damage in the form of crack growth was more prevalent in the region near the supports.

Modified Layered-Sectional Analysis for Forensic Investigation

AbstractThis paper describes a modification to the layered-sectional analysis approach, which provides the engineer with a tool to assess structural behavior of concrete beams with localized damage, a problem not well suited to classical, closed-form solutions. The modified layered-sectional analysis (MLSA) framework is applied to a forensic investigation case study in which two prestressed double-tee beams are exposed to a short duration, intense fire in a parking structure. The results of the MLSA are within 1% of the case study load test, which indicates that the MLSA could be a useful, computationally efficient tool for the investigating engineer to predict the postfire serviceability and strength of damaged beams, and potentially eliminate the need for expensive load testing. A short parametric study is included for the research engineer interested in the MLSA for predicting the postdamage behavior of non-standard materials such as enhanced sustainability concrete (ESC).

A parking structure in Moscow

This article describes the design of a parking structure for the Golovino residential complex in Moscow as part of a design-build contract with the Krost Companies. The precast concrete structure is the first in Russia to use pretopped double tee beams, and the structure's design has undergone careful scrutiny because of its novel features. The author discusses the process of obtaining the building permit and challenges to the building process, which have included the development and consistent production of the right concrete mixture for both durability in cycles of freezing and thawing and resistance to chloride-ion intrusion. Also described are the cost savings that have resulted from choosing precast concrete pretopped double tees instead of typical cast-in-place concrete construction.

Long-term lateral deflection of precast, prestressed concrete spandrel beams

Slender precast concrete spandrels are used to increase cost effectiveness of precast concrete parking structures. They reduce the number of column lines in building floor plans and the number of elements to transport and erect. However, these spandrels can be prone to larger deflections, as the increased slenderness can reduce sectional stiffness. Design of these structures should also consider vertical and lateral deflections because of the eccentric loading transferred from the deck double-tee beams. In this paper, the authors provide realistic estimates of long-term deflections for the next generation of spandrels. They also examine the sensitivity of long-term deflection to parameters such as spandrel type, span length, creep and load eccentricity. The results of their numerical study included the finding that long-term lateral deflections are less than corresponding lateral deflections.

Experimental Evaluation of Effect of Flange Dimensions on Shear Behavior of NSC and SCC Double Tee Beams

Experimental Evaluation of Effect of Flange Dimensions on Shear Behavior of NSC and SCC Double Tee Beams

Elastic Solutions for Eccentrically Loaded, Slender, Rectangular Spandrel Beams

AbstractSpandrel beams in precast concrete buildings are widely used to support double-tee deck beams, particularly in parking garages. Spandrel beams of deep cross-sections, resisting eccentric loads from double-tee beams, can be susceptible to excessive lateral deformations and serviceability failures before reaching their strength limits. However, closed-form solutions for estimating lateral deflections in such members are not available in the technical literature. In this paper, approximate analytical solutions for the deflection of beams with thin rectangular sections are derived from second-order elastic analysis, and they are proposed for use in estimating maximum lateral deflections in spandrel beams under eccentric and uniformly distributed loads. Continuous lateral support is provided at the elevation of the floor deck to the spandrel beams. Thus, two cases are considered: one for laterally restrained beams under typical service conditions, and a second for laterally unrestrained beams prior to ...

Experimental Behavior of Mechanical In-Flange Connectors

Prestressed double-Tee beams are used in multi-level parking structures and in some states' bridges. Steel brackets, called in-flange connectors, are embedded in the flanges of the beams and are welded together on-site to facili- tate system behavior. To date, placement, i.e. spacing, of these connectors has been based primarily on engineering judg- ment although some guidelines are available. This paper summarizes the results of seventy (70) monotonic and twenty- three (23) reversed-cyclic tests on double-Tee in-flange connectors in an effort to provide comprehensive information on the relative performance of several different available connectors. Test results are reported for six different connectors manufactured by two different companies using seven different test protocols described herein. Each connector was imbedded in a 965x914x102 mm (38x36x4 in) concrete slab designed to be representative of the overhanging portion of the flange of a concrete double-Tee beam. The connectors were also tested using a slow reversed-cyclic displacement con- trol protocol and the ability of each connector to dissipate/absorb energy is also discussed, along with the relationship to serviceability-related concrete damage, i.e. cracking and spalling.

Dapped-End Strengthening of Full-Scale Prestressed Double Tee Beams with FRP Composites

The unusual shape of the dapped-end beam develops a severe stress concentration at the re-entrant corner. If suitable reinforcement is not provided close to the re-entrant corner, the diagonal tension crack may grow rapidly and failure may occur with little or no warning. This paper reports the testing of three full-scale prestressed concrete (PC) double tee beams (five tests) in shear at the re-entrant corner. One dapped-end of each beam was reinforced with internal steel reinforcement as a bench mark and the other was strengthened with externally bonded carbon fiber reinforced polymer (CFRP) laminates. Of the two CFRP strengthened dapped-ends one used one-ply externally bonded CFRP reinforcement and the other two-ply externally bonded CFRP reinforcement with a U-anchor. The tests revealed that the reinforcement arrangements have significant influence on the member response. For one of the CFRP cases, the application of the anchor was such that failure by fiber rupture rather than peeling was achieved. Results from design computations were confirmed.

Truck Load Distribution Behavior of the Bridge Street Bridge, Southfield, Michigan

This article presents the major results and details from a structural load test performed on Structure B of the Bridge Street Bridge Deployment Project in Southfield, Michigan. Structure B is the first prestressed concrete bridge in the U.S. to be almost entirely reinforced with carbon fiber reinforced polymer. Structure B is designed to accommodate two traffic lanes and incorporates three 68.9 ft (21 m) long, 27.9 ft (8.5 m) wide spans skewed at an angle of 15 degrees relative to the substructure. There are 12 double-tee beams (four beams per span), each incorporating internal pretensioned tendons and external post-tensioned carbon fiber composite cable tendons. The authors analyzed the measured strains and deflections from various bridge span load configurations for evaluating load distribution behavior. The authors also compared data from a laboratory test of a full-scale prototype double-tee test beam conducted prior to bridge construction with data obtained from the field load test of Structure B. The authors conclude that the three spans of the bridge exhibit similar load distribution behavior. They note that, as determined from the measured strain response in the beams, the actual distribution of the applied loads within each span in general conforms with the provisions contained in the AASHTO Specification.

Uniform Serviceability Load Limits for Mechanical Flange Connectors

Multilevel parking structures are often constructed using prestressed concrete double-Tee beams that form their floor and roof diaphragms. Mechanical flange connectors are typically used to connect the flanges of these beams. Cracking of the concrete around the connectors is a common problem requiring significant person-hours to repair and maintain. This paper presents suggested design load levels that may significantly reduce the cracking in these structures based on the results of 49 monotonic displacement control tests performed on 6 different types of commercially available mechanical flange connectors embedded in concrete slabs. The slabs were designed to be representative of the overhang on a typical precast concrete double-Tee beam. Three different types of monotonic tests were performed: horizontal shear, vertical shear, and tension. Basic statistics were then used to analyze the data from each of these three test types and the load ranges were divided into four regions, termed cracking unlikely, ...

Static flexural response of members pretensioned with multiple layered aramid fiber tendons

Abstract This paper presents the results from an experimental investigation to study the feasibility of using aramid fiber tendons as prestressing strands in concrete girders. The work reported in this paper is part of a large test program to evaluate the flexural, shear and fatigue behavior of a prestressed 10.0m (33 ft) long, 1:2 scale concrete bridge model. The bridge model consisted of three precast double-tee concrete girders prestressed with aramid tendons and post-tensioned together in the transverse direction to form the bridge model. One model double-tee beam was tested to failure prior to the construction of the 1:2 scale model bridge. This paper presents the results of the flexural tests on this girder. The prestressed double-tee girder was tested to failure under four-point static loading. The test results indicate satisfactory bond behavior of ARAmid PREstressing Element (ARAPREE) tendons up to failure. Linear and non-linear analyses of the beam were performed and compared to the experimental results. Analytical results correlated well with those observed in the experiment. The important aspects of evaluating the structural performance, such as pretensioning technique, prestress losses, and transfer length of ARAPREE tendons, flexural responses and ductility, are discussed.

Fatigue Strength of Joints in a Precast Prestressed Concrete Double Tee Bridge

The feasibility of using precast, prestressed double tees to form a monolithic bridge system is examined by conducting static and fatigue load tests on a 1:3.5 scale model of a two-span, transversely and longitudinally post-tensioned, continuous double tee beam system. Constant amplitude fatigue loading was applied on the model at t ypical locations simulating HS20-44 AASHTO truck loading. The behavior of the bridge system was evaluated with regard to structural integrity. Crack widths in the longitudinal and transverse joints were monitored with increasing cycles of fatigue loading. A finite element analysis of the bridge system was carried out using orthotropic modelling, and the deflections were compared with experimental values. The ultimate load, computed from plastic analysis, was found to be in good agreement with the measured value. The study established the feasibility and structural adequateness of the precast concrete double tee concept for short and medium span highway bridges in Florida and elsewhere.