Precast Concrete Columns Research Articles

Structural Design and Technology of Pocket Foundations for Long Precast Concrete Columns in Seismic Areas

Structural Design and Technology of Pocket Foundations for Long Precast Concrete Columns in Seismic Areas

Seismic behavior of resilient concrete column-base connection with SMA bolts and RSPs

This paper presented a novel resilient concrete column-base connection with shaped memory alloy (SMA) bolts and rectangular slotted plates (RSPs) to achieve the demountable and recoverable capabilities in precast concrete columns. Quasi-static tests were conducted on one monolithic and three resilient concrete connections to investigate the effects of RSP number and yield strength on seismic behavior. Results showed that the resilient connection with both flange and web RSPs had superior lateral capacity, ultimate drift ratio, and energy dissipation compared to the monolithic connection. The resilient connection also exhibited minimal concrete damage and smaller residual deformation. However, low-yield-strength flange RSPs significantly reduced lateral capacity, initial stiffness, and energy dissipation, which should be considered in engineering design. Additionally, adjustment coefficients for rocking interface rotations were determined from digital image correlation (DIC) data using a fitting method. A formula was proposed to predict the flexural capacity of resilient specimens, assuming a plane section in the compression zone. The predictions closely matched the test data, with differences within 10 %, demonstrating the formula's effectiveness. The length, diameter, and material yield strength of the anti-shear steel bar (ASB) had a significant impact on the shear capacity of the interface.

Seismic analysis of bridge with buckling‐restrained brace posttensioned concrete pier

AbstractA two‐span bridge built with a two‐column pier consisting of unbonded posttensioned precast concrete columns and a buckling‐restrained brace (BRB) is analyzed using a three‐dimensional nonlinear numerical model. Seismic damage to the pier is eliminated through rocking of the posttensioned columns and seismic energy dissipation by the BRB. The numerical model is calibrated with experimental results of posttensioned columns and BRB structural elements. Seismic assessment of the bridge pier is performed using the ratio of BRB axial force to base shear as the parameter of interest. Limits for the seismic performance of the bridge pier are established by means of nonlinear static analysis using OpenSees. Bidirectional ground motions are used to perform probabilistic hazard analysis through nonlinear time history simulations. Three damage limit states are defined in this research: the activation point of posttensioning bars, the maximum base shear capacity or onset of concrete spalling, and collapse defined as the state at 20% loss of maximum base shear capacity. The analysis results are formulated into fragility curves for the three damage states as well as the residual drift. The fragility curves could be used for preliminary seismic bridge design. The analysis shows that the BRB dissipates significant seismic energy and the posttensioned concrete columns reduce residual displacements so that the bridge pier can remain functional after severe earthquakes. The fragility approach for designing bridge piers constructed with posttensioned concrete columns and BRB elements is a significant improvement over conventional seismic bridge design and can contribute to functional recovery after severe earthquakes.

Connections between precast hollow concrete columns and foundations using UHPC and rebar lap splices

Hollow concrete columns (HCC) have been widely used in accelerated bridge construction worldwide. The column-foundation connections are vital in such precast systems to ensure seismic resilience. In this paper, a novel HCC-foundation connection using UHPC and rebar lap splices was proposed, which could facilitate the construction process. Cyclic tests were carried out on four specimens to examine their seismic performance. Test results showed that the proposed connections exhibited satisfying capacities, ductility, and energy dissipation comparable to monolithic connections under lateral cyclic loads. The use of a precast UHPC shell did not deteriorate the performance of the connection with no interface separation observed. The decrease in joint height would, however, bring about anchor rebar slippage and reduce energy dissipation. A validated fiber element model of the specimens was established for efficient seismic modeling of precast systems with the proposed connection in actual projects. Force transfer mechanisms and design methods for the connections were further deduced. The proposed connection has been verified to be comparable to cast-in-place connections and is thus suitable for use in precast column-foundation connections. Several design recommendations were derived for engineering reference.

Impact resistance and performance of precast shear walls with various connections under axial and lateral loads

This study conducted pendulum impact tests on three precast concrete (PC) shear wall specimens with various connection types and one cast-in-situ reinforced concrete (RC) shear wall specimen to investigate their behavior under out-of-plane impact loads at a consistent axial compression ratio. The study reported observations on failure patterns, the progression of cracks, the dynamics of impact force over time, relationships between axial force and vertical displacement, deformation behavior, and the strains in concrete and rebars. Through comparative analysis with similar PC columns, the influence of various connections on the impact resistance is analyzed for both shear walls and column specimens. It was found that all PC specimens showed flexural failure modes akin to those of the RC specimen, yet with more extensive cracking and lower stiffness. PC specimens with grouted sleeve connections demonstrated satisfying impact resistance that emulates the performance of cast-in-situ walls. Specimens with grouted corrugated metallic duct connections demonstrated obvious localized damage. Eventually, the study proposes a novel method for rapidly evaluation of the impact resistance of concrete shear walls.

Post-fire seismic performance of precast concrete columns with grouted sleeve connections: An experimental study

This research explores the effects of fire on the seismic behavior of precast concrete columns with grouted sleeve connections. Five precast columns were subjected to fire for 0, 60, and 97 min, then tested under axial loads and horizontal cyclic loading at compression ratios of 0.1 and 0.3. A comparative analysis was performed against a cast-in-place column, identically treated. The study found that fire exposure alters failure modes: non-exposed columns failed flexural, while those exposed for 60 min showed either flexural shear or shear bond failures, varying with axial compression. After 97 min fire exposure, shear bond failure was predominant. Fire exposure duration was inversely proportional to load-bearing capacity, ductility, stiffness, and energy absorption. Conversely, higher axial compression ratios increased load capacity and stiffness but decreased ductility, without significantly affecting energy absorption post-fire. The study culminates in a refined calculation method for estimating post-fire load capacity, achieving accuracy within 5 % error.

Numerical investigation of plastic hinge length and lateral displacement capacity in precast concrete columns reinforced with SFCBs

Basalt fiber-reinforced polymer (BFRP) presents several advantages, including a moderate elastic modulus, cost-effectiveness, and a substantial fracture strain. A steel-FRP composite bar (SFCB) is a composite bar consisting of an inner steel bar and outer longitudinal BFRP, and it offers favorable initial modulus, high durability, and controllable post-yield stiffness. This study aims to address the issue associated with poor corrosion resistance, connection defects, and low integrity in traditional precast concrete columns with grouted sleeves (PCC-GSs) by employing bond- and post-yield-controlled precast concrete columns reinforced with SFCBs (PCC-SFs). The 3D finite element analysis (FEA) modeling was validated by comparing the results with those of six PCC-SFs and three precast reinforced concrete (RC) columns obtained from the experiment. The results encompass failure modes, load-displacement responses, strain distributions of SFCBs, and section curvature along the columns. The predicted errors for the peak load of S10B85–1P, S10B85–2P, and S10B85–3P are 6.4%, 0.1%, and 1.9%, with a mean error of 2.8%. The predicted errors for the ultimate deformation of S10B85-3PL and ST10B85–3P are within 20%, with a value of 6.0% and 18.7%. Subsequently, a series of FEA models were developed to analyze the effects of various on the development mechanism of plastic hinge length (PHL) for the PCC-SFs under lateral loading. The parameters included the post-yield stiffness ratio, equal-stiffness reinforcement ratio, axial force ratio, concrete strength, and bond strength. The longest plastic hinge length can reach 1.91D (D is the width of the column). An adjusted prediction model for the equivalent PHL in PCC-SFs was proposed and evaluated following a discussion of existing empirical models. Finally, the study explored the effects of these parameters on the load-displacement response, and the rationality of Priestley's shear-strength degradation model in PCC-SFs was validated. Based on the CEN model, an improved prediction model of the total chord rotation capacity was proposed.

Pullout test for PC column-capital grouted rebar connection with corrugated duct

Double-beam precast concrete (PC) structures require large capitals to support a wide PC girder. In this study, a segmented PC column-capital system is developed to overcome the disadvantages of conventional PC columns in terms of manufacturing, transportation, and construction. In the proposed segmented PC column-capital system, large PC capitals are assembled with PC columns using the proposed corrugated rebar connections filled with grouted mortar. To verify the load-transfer capacity of the proposed corrugated rebar connections, pullout load tests are conducted under various test parameters, including the mortar compressive strength, curing time, bond length, and embedment length. To enable rapid construction, a relatively short curing time of 1–2 days is addressed. The test results indicate that the pullout performance of the proposed corrugated rebar connection is primarily affected by the mortar compressive strength fm’ and embedment length ld. When fm’ > 7.9 MPa and ld = 800 mm, the proposed corrugated rebar connection transfers tensile loads corresponding to construction loads. When fm’ > 21.0 MPa and ld = 800 mm, the proposed rebar connection can resist the tensile yielding load of the connected vertical rebar even after one-day of curing. However, when ld is less than 800 mm, bond-slip failure occurs because of the insufficient bond length. Based on the test results, a parametric analysis is conducted using a finite-element model. Similar to the experimental result, the numerical result shows that the bond strength of the proposed rebar connections is significantly affected by fm’ and ld. Hence, a bond-strength model of less-hardened grouted mortar with a bond stress of τb = 0.20 fm’ is suggested based on the previous and present test results as well as parametric analysis results.

Experimental investigation of the mechanical performance of novel rigid connections in prestressed circular composite precast concrete columns under cyclic lateral loading

The present study introduces an advanced design of Prestressed Circular Composite Precast Concrete Columns (PCCPCCs), which have been applied in real-world structures, equipped with two novel rigid connection types (i.e., the reinforcing-cage connection and the welded-plate connection) to address existing challenges in the design, construction, and quality control of traditional precast concrete (PC) columns. Five full-scale specimens were experimented individually to assess the mechanical performance of PCCPCCs subjected to cyclic lateral loading and constant axial loading. The results indicate that the specimens exhibited no signs of collapse or loss in axial load capacity during the tests. Furthermore, all specimens met or exceeded the performance criteria set by relevant standards, such as GB50011-2010 and ACI 374.1-05, regarding drift ratio, moment capacity, energy dissipation, and ductility. It demonstrates that the novel design of PCCPCCs proposed in this study can be integrated into practical construction projects designed as lateral-force-resisting systems, such as moment-resisting frames and bridges, to accommodate diverse construction project requirements.

Seismic performance verification and theoretical stiffness calculation for a novel assembled concrete dry-connected beam-column node

This paper proposes a novel assembled concrete dry-connected beam-column node, which consists of a precast concrete beam with steel haunch plates at the end and a precast concrete column connected by ordinary strength long bolts. The quasi-static test study and finite element numerical simulation of the node are used to analyze the hysteresis curve, skeleton curve, and other performance indexes and investigate mechanical properties under low-cycle reciprocating load. The results demonstrate that the overall stress performance of the column specimen is outstanding; the specimen node possesses large deformation and good ductility, presenting semi-rigid characteristics; the damage of the specimen mainly includes the bending deformation of the connecting bolts. By analyzing the damage and force mechanisms of the node, an "equivalence method" for the initial rotational stiffness calculation of the beam-column combination node is established. Moreover, the formula for calculating the stiffness of this semi-rigid node is deduced.

Experimental study and numerical simulation of a structural concrete column for building heating integration and energy storage

A steel pipe assemblage is integrated into a structurally reinforced precast concrete column to demonstrate thermal energy storage (TES) and space heating capabilities. This thermal energy column is heated via hot water at varying flow conditions. The system is used as a thermal storage medium, as a means of reducing the demands on the building heat pump, and for regulating the thermal comfort of the building interior environment. The thermal performance of the energy column is examined experimentally and numerically in both charging and discharging phases. Two examples are used to demonstrate the improvements in the operation of building thermal equipment and in the building thermal environment offered by either passive or active discharging of the energy column. Following the conclusion of thermal evaluation, the structural performance of the column under axial compression was evaluated by loading the system to failure. The experiment was paused for visual observation at both the service level and nominal capacity milestones. The longitudinally embedded steel pipes developed comparable strains to the column longitudinal steel reinforcing bars. The structural capacity of the energy column can be accurately predicted using standard concrete design approaches that account for the mechanical influence of the embedded steel pipe assemblage. It is demonstrated that the developed concrete energy column provides a viable option for improving the building thermal energy efficiency and maintaining structural performance.

Mechanical Behavior of Precast Circular Semi-Continuous CFST Columns under a Uniaxial Eccentric Load

For this study, we conducted a detailed examination and comprehensive comparative analysis of the structural responses and mechanical behavior of bolted sleeve connections in precast circular semi-continuous steel tubular concrete (PCSCFST) columns. The research involved fourteen specimens, and we considered the impacts of various parameters, including eccentricity, external steel sleeve thickness, bolt diameter, and slenderness ratio. The findings revealed that the external steel sleeve significantly enhances the protection of the connection area, enabling the bolts to effectively withstand eccentric loads. However, sleeves that are too thick may lead to premature bolt failure, reducing their ultimate load-bearing capacity. Using bolts to transfer loads to the concrete significantly strengthens the restraining effect of the steel sleeve. Nonetheless, increasing the bolt diameter beyond a certain threshold may diminish this beneficial impact, potentially leading to connection failure and a decrease in ultimate load-bearing capacity. A new ‘cooperative value q’ measures component collaboration at ultimate capacity, showing that shorter columns offer less effective coordination than longer ones. Through regression analysis, we formulated a prediction for axial ultimate bearing capacity, closely aligning with the experimental data (Npre-a/Nu average value of 1.003, variance 0.00248). Three N–M curves, including the Eurocode 4 method, offered conservative predictions, with Eurocode 4 closely matching the experimental results. A refined prediction method following Eurocode 4 was developed, yielding an average Ppre-U/Pu value of 0.971 and a variance of 0.0107.

Assessing the Seismic Performance of Exterior Precast Concrete Joints with Ultra-High-Performance Fiber-Reinforced Concrete

This study was conducted to evaluate the seismic performance of an exterior precast concrete (PC) beam–column joint with ultra-high-performance fiber-reinforced concrete (UHPFRC). Currently, 45 MPa non-shrinkage mortar is used as grouting for the connection between PC beams and columns. In this study, PC joint specimens were designed using 45 MPa non-shrinkage mortar and 120 MPa UHPFRC as a grouting agent for connecting PC members. The shear reinforcement effect of UHPFRC was confirmed to reduce shear cracks in the joint core; this trend was similar in the specimens with reduced shear rebars. The maximum moment of the test specimen with the corbel was slightly increased, but there was no significant difference, and the failure pattern also showed similar results to the specimen without the corbel. In the test specimen to which the U-shaped beam was applied, the attachment surface of ultra-high-performance concrete and normal concrete were separated, and a large decrease in strength was observed. Considering workability, U-shaped beam do not seem to have any major merits in general, such as increased strength and difficulty in manufacturing, and it was judged that it was effective to separate the PC beams from the column face through corbels. Shear reinforcement through UHPFRC is effective in relieving congestion by reducing shear reinforcement bars at the joint, and it is judged that it can be used as PC joint grouting due to its excellent fluidity.

Blast resistance of grouting sleeve connected precast concrete columns under close-in explosions

Attributed to the promotion of environmental protection and efficient construction, the precast concrete (PC) columns are gradually replacing the traditional reinforced concrete (RC) columns as the main load-bearing members of building structures. However, with the aggravation of deliberate or accidental explosions, there is a lack of study on the damage modes as well as dynamic responses of grouting sleeve connected PC columns. To systematically assess and compare the blast resistance of PC and RC columns, four PC columns and two control RC columns were firstly fabricated and tested under close-in explosions, in which the influences of the scaled distance (0.50 m/kg1/3 and 0.61 m/kg1/3), burst height (1/4- and 1/2-heights of column, i.e., 0.75 m and 1.5 m) and axial compression ratio (0.18 and 0.36) were experimentally examined. Secondly, the present test on PC/RC columns and the existing contact explosion test on PC specimens were numerically simulated. The reliability of the adopted numerical simulation approach was comprehensively verified by comparing the test and predicted incident and reflected overpressure-time histories, as well as the damage modes and displacement-time histories of specimens. Finally, the blast resistances of the prototype PC and RC columns under four design basis threats specified by U.S. Federal Emergency Management Agency were assessed, and the corresponding site mitigation measures were proposed. It indicates that, compared with RC columns, PC columns exhibited greater blast resistance, i.e., slighter maximum and residual lateral displacements, as well as concrete spalling sizes. However, both of PC and RC columns cannot survive under the contact explosion of suicide vests (9 kg of TNT equivalence) or the explosion induced by sedan bombs (454 kg of TNT equivalence) near the sidewalks at the standoff distance of 4 m.

Load-bearing capacity of precast recycled aggregate concrete column-to-column connections

Recycled aggregate concrete (RAC) often shows different strength and deformation properties from natural aggregate concrete (NAC) and may therefore have an impact on the connections between precast concrete elements. In this work, three simple connections between precast concrete columns were considered, including a wet connection with bedding mortar, a dry connection without bedding mortar and a monolithic joint with plain concrete. An industrially produced coarse recycled concrete aggregate (RCA) was used to partially or fully replace a coarse natural aggregate in the concrete. A total of twenty-two 200 mm × 200 mm × 500 mm reinforced concrete columns were prepared and tested under axial monotonic loading through displacement control. The results show that regardless of RCA content, the equation specified in ACI 318 (ACI, 2019) and the one proposed by Vambersky (1990) provide safe estimates of the load-bearing capacity of wet connections between reinforced RAC columns.

Repairable Precast Concrete Bridge Columns for Seismic Events

In multispan bridges excited by ground shaking, columns are usually the target ductile members. Although current practice is successful in attaining the no-collapse objective for bridges, columns are usually damaged at displacements associated with this performance level. Minor damage can be repaired, but excessive damage is usually beyond repair. A new design paradigm with minimal damage and repair need is gaining interest. The benefits of such a design can be increased if low-damage technologies are combined with accelerated bridge construction techniques. The main goal of the present study was to develop rein¬forced concrete bridge columns that are fully precast concrete, low damage, and repairable through compo¬nent replacement. To achieve the project objectives, 20 repairable precast concrete alternatives were developed and ranked. Subsequently, the top three candidates were designed at 50% scale, constructed at a precast concrete plant, and tested in a laboratory. The precast concrete columns incorporated different exposed fuses, such as stainless steel bars and steel tendons, advanced materials such as ultra-high-performance concrete, a self-centering mechanism, or an accelerated bridge construction socket connection. A reference cast-in-place concrete column was included for comparison. Each precast concrete column was tested twice. It was found that the repair of the precast ultra-high-perfor¬mance concrete columns with exposed tendons was easy,

Project Spotlight: Nashville courthouse clears the air using special concrete

Innovation and resilience are at the heart of the Fred D. Thompson U.S. Courthouse and Federal Building, a structure that leverages precast concrete to perfectly marry classic appeal with a contemporary aesthetic. For the Nashville, Tenn., courthouse, the U.S. General Services Administration sought a design approach reflective of the U.S. justice system. Thanks to the use of precast concrete panels, columns, and box beams, this was accomplished in several ways. The building’s facade is symmetrical, reflecting the need for balance in the courtroom. The panels are white, emphasizing the court system’s ideal state as a conveyor of truth and balance in U.S. society and government, and the building’s stately presence is a reminder of U.S. stability, a characteristic shared with the precast concrete elements that made it possible. GATE Precast was the precast producer for the project.

Shear transfer in bolted precast concrete column connections

Shear transfer through bolted precast concrete column connections is not a widely studied topic. The current design method is based on the standards for steel structures, and the developers adjusted it to conform with previous shear test results. The method adjusted for design in the ultimate limit states may not be suitable for assessing performance in the serviceability limit states, where the maximum shear force is limited either based on unallowed deformations or displacement. This paper assesses the suitability of the current design method for evaluating the maximum shear force in the serviceability limit states. When the authors applied the current method with load and safety factors usable in the serviceability limit states and compared the analytical results against the experimental data, they concluded that adjustments to existing design methods are needed. Improvements for design in the serviceability limit states are proposed.

Ductility of Precast Concrete Column Beams Using Dowels

Precast concrete structures are considered as monolithic structures, flexural reinforcement and beam column joint shear can be planned based on design capacity. This research is an experimental study. The objective is to assess the ductility of precast concrete column beams utilizing dowels. The test specimens comprise three configurations: monolithic beam column (BN), 2 post precast beam column (BG 1), and 4 post precast beam column (BG 2), with respective displacement values of 37.4 mm, 42.7 mm, and 47 mm. This research was carried out in the stages of calculating displacement ductility using displacement parameters, and curvature ductility using parameters of cross-sectional curvature or curvature values and load values due to cyclic loads. The research results show that the displacement ductility values for test specimens BN, BG 1 and BG 2 are 2.34, 2.21 and 2.06 respectively. The curvature ductility value for test specimens BN, BG 1 and BG 2 is more than the value required in ASCE 41-17, namely 0.01 in the LS condition and in the CP condition it is 0.015. Additionally, these values surpass the stipulated requirements. This leads to the conclusion that beam column connections, whether monolithic or precast, exhibit exceptional performance in withstanding earthquake loads under both moderate seismic conditions (moderate earthquakes) and severe seismic conditions (strong earthquakes)

Estimation and analysis of the cumulative energy damage model for precast concrete nonrectangular column frame structures

A detailed characterization of structural damage progress is essential to performance-based seismic design for precast concrete nonrectangular column (PCNC) frame structures. The paper presents an experimental investigation into the damage behavior of the PCNC frame structures under reverse cyclic loading, including specimens PCFS1 and PCFS2 in bay and specimen PCFS3 in depth of a new precast residential building. Based on the experimental results, the damage mechanism of the PCNC frame structures was further discussed with the cumulative energy damage model proposed in this paper, and the influence of key structural parameters on the damage of the PCNC frame structures was examined, including energy dissipation adjusted factor, the residual deformation rate and the stiffness degradation rate. Available results indicated that the experimental damage curves of test specimens increased with the loading progress and acted with nonlinear damage characteristics, and PCNC frame structural damage behavior was sensitive to the axial compression ratio. For the proposed damage model, the calculation results were in good agreement with the experimental results. On the basis, the damage degree of the PCNC frame structures was divided into five performance levels including normal use, temporary use, use after repair, life safety and prevent collapse in the defined damage range of (0, 1). Elastic layer drift ratio limit was suggested to relax for PCNC frame structures. Final test results could provide a basis for the aseismic design and damage assessment of such structures after earthquake.