Precast Concrete Columns Research Articles

Seismic Analysis of Posttensioned and Hybrid Bridge Bents with Buckling Restrained Braces

A numerical model is presented for a rocking bridge bent specimen consisting of two precast concrete columns with posttensioning (PT) bars, two footings, and a cap beam, with or without a buckling restrained brace (BRB). First, a numerical model of the posttensioned bridge bent specimen without a BRB is developed; emphasis is placed on modeling the rocking mechanism at the joint between precast concrete members joined only through PT bars. The numerical model is extended to a hybrid specimen consisting of a two-column posttensioned bridge bent with a BRB as an external energy dissipation device. Experimental results obtained from quasi-static cyclic tests of the posttensioned and hybrid specimens are compared with the numerical models. Satisfactory agreement of the numerical models with the experimental results is observed in terms of structural response, hysteretic energy, and PT-bar forces. The numerical models are subsequently extended to a previously tested three-column bridge bent for two configurations: (1) a posttensioned bridge bent with PT bars, and (2) a hybrid bridge bent with PT bars and two BRBs. A fiber-based bridge bent model is built, which includes soil–structure interaction (SSI) using simplified springs. A comparison of the posttensioned and hybrid bridge bents using far-field and near-field ground motions shows that the hybrid bridge bent displays superior performance compared with the posttensioned-only bridge bent.

Experimental study on seismic behaviour of precast recycled fine aggregate concrete columns with pressed sleeve connections

In this paper, the seismic behaviour of precast recycled fine aggregate (RFA) concrete columns with pressed sleeve connections was investigated experimentally, in order to prove the potential for utilising RFA and pressed sleeves in new concrete construction. The upper and lower columns of the specimens were manufactured using recycled aggregate concrete (RAC) and the longitudinal reinforcements were connected by pressed sleeves during assembly on site. Ten columns with 400 mm × 400 mm cross-section were designed and tested under cyclic loading, considering various parameters including the axial compression ratio (from 0 to 0.55), longitudinal reinforcement ratio (1.01 %, 1.59 % and 2.45 %), replacement ratio of RFA in concrete (0, 30 % and 70 %) and manufacturing method (cast-in-situ and precast) for comparison. Their failure process, hysteretic behaviour, strength, stiffness and ductility as well as energy dissipation were studied. The specimens all experienced cracking, yield, ultimate and failure phases during the test. The ultimate drift angle ranged from 1/57 to 1/16. The lateral bearing capacity of the specimen increased with the augment of the axial compression ratio or the longitudinal reinforcement ratio within the range of experiment parameters. The experimental results demonstrated the favourable performance of longitudinal reinforcements connected by pressed sleeves, and the feasibility of using RFA concrete in this type of precast column. The theoretical calculation for the strength of the columns based on Chinese code GB 50010-2010 and American code ACI 318-19 was then performed, and the obtained results were compared with the experimental ones. It was shown that the experimental flexure-compression strengths were 0.99 ∼ 1.25 and 1.03 ∼ 1.34 times the theoretical values calculated based on GB 50010 and ACI 318, respectively, which indicated the calculation methods proposed in current concrete structures codes could be used as references for the structural design of the precast RFA concrete columns with pressed sleeve connections.

Experimental fire performance assessment of a new type of prestressed composite circular precast concrete columns

The purpose of this paper is to study the fire resistance of a new type of prestressed composite circular precast concrete column (PCCPCC) consisting of a prestressed precast concrete hollow pipe and cast-in-place core concrete filled in the hollow section through a combined numerical and experimental approach. The potential advantages of PCCPCCs lie in their low manufacturing costs and high construction efficiency. A series of fire tests were conducted on PCCPCCs with consideration of different precast concrete strengths, rebar layouts, and axial loads, where the column damage patterns, fire exposure time, and vertical displacements of all the specimens were experimentally examined. Their post-fire residual strengths were also determined via uniaxial compression tests. Finite element (FE) simulations were also conducted and the obtained results were compared to the corresponding test outcomes. The results show that the fire resistance of PCCPCCs is largely dependent on the imposed axial loading, and an effective thermal isolation effect from the prestressed precast concrete hollow pipes was identified. The further research on this new column form is necessary for the possible future wide adoption.

Cyclic response of precast concrete columns connected with cast-in-place UHPC in plastic hinge region

Ultra high performance concrete (UHPC) is a promising material for lap splice connection of steel bars in reinforced concrete (RC) precast structures given its high compressive strength, its high toughness, and its high bond strength with steel bars. This paper focuses on the cyclic response of bottom frame columns connected by UHPC in the plastic hinge region. The effect of lap length of longitudinal bars in UHPC (6d, 8d and 12d, d = diameter of longitudinal bar), axial load ratio and stirrup ratio of the UHPC connection region on the global response of the columns were presented and analyzed, and a cast-in-site RC column was prepared for comparison. The behavior of the UHPC connected columns was flexural dominated, but columns with 6d and 8d lap length failed due to the gradual bonding degradation between UHPC and longitudinal bars, and the column with 12d lap length failed due to UHPC crushing. It was demonstrated that a 8d lap length could achieve equivalent lateral bearing capacity and ductility to the control RC column, but the lap length should be greater than 8d when applying UHPC connection technology in seismic regions to ensure the energy dissipation. Column with lower axial load ratio (0.17) exhibited lower ductility because shear sliding occurred between the interface of UHPC and footing at the post-peak stage. The UHPC connected specimens exhibited higher resilience and better damage resistance in earthquake because the ratios of the residual displacements to the corresponding peak displacements were between 17 and 39%. Besides, a flexural capacity model for the columns was developed and the results predicted by the model agreed well with the experimental results.

Experimental Research on Seismic Behavior of Haunched Concrete Beam–Column Joint Based on the Bolt Connection

Studying the seismic performance of assembled beam–column joints is essential for the development of assembled frame structures. In this paper, a novel dry connection beam–column joint with a high degree of modularity and a simple structure is proposed and tested using a pseudostatic test. The joint is composed of a precast concrete beam with a steel axillary plate at the end and a precast concrete column connected by long bolts. By analyzing the characteristics of the hysteresis curve, skeleton curve, and stiffness degradation curve, we were able to investigate the seismic performance of this novel new joint under low circumferential reciprocating load as well as the impact of bolts of various strength grades on the joint’s seismic performance. The results illustrated the robust overall bearing performance of the newly assembled beam–column joint. However, when connected with common bolts, the joint deforms more, exhibits good ductility, clearly displays semi-rigid characteristics, and performs better in terms of energy dissipation. This contrasts with connecting with low-strength bolts, which cause the joint to deform little and have poor energy dissipation capacity. The prefabricated columns and beams remain undamaged, making it possible to quickly repair the assembled building structure after an earthquake; however, the joints are harmed due to the bending and fracture of the connection bolts. It has been suggested that researchers add damping energy dissipation devices to the new joint to increase its energy dissipation capacity and control the joint’s overall deformation because the joint’s energy dissipation capacity is insufficient under the low circumferential reciprocating load.

Experimental investigations of precast concrete column with spliced connections based on ultrahigh‐performance fiber‐reinforced concrete

AbstractWhen compared with normal concrete, ultrahigh‐performance fiber‐reinforced concrete (UHPFRC) could signally enhance the bond with reinforcing bars. Accordingly, incorporating UHPFRC to connect precast concrete columns allows smaller bar splice lengths and provides ease of construction. In this article, a two‐stage research program was presented. First, the behavior of double‐row spliced rebars in UHPFRC was tested under direct tension, and the bars adopted internal strain measurement to characterize the bond stress distribution along the splice length. The failure of specimens was governed by UHPFRC splitting, and the bond stress of spliced rebars in UHPFRC presented a two‐local peaks profile. Second, the hysteretic performance of precast concrete columns with spliced connections based on UHPFRC was determined by full‐scaled cyclic tests and numerical simulations. Precast columns with UHPFRC connections at the column base exhibited similar ductility, energy dissipation capacity, and higher bearing capacity to the monolithic concrete columns. Finally, some practical considerations and recommendations were proposed.

Development of a novel shape memory alloy‐based self‐centering precast segmental concrete column

Development of a novel shape memory alloy‐based self‐centering precast segmental concrete column

An experimental study of the shear behavior of joints in precast concrete columns

The shear behavior of joints in precast concrete columns with a new type of column-to-column connection was investigated in this research. Shear tests were performed with 12 precast concrete columns. The influences of the shear key width (0, 70 mm, 100 mm), the diameter of the reinforcement across the joint (0, 16 mm) and the axial compression load ratio (0.3, 0.4, 0.5) on the shear performance of the joint were studied. An expression to give the prediction of the shear capacity of such joints is proposed. The data show that: (1) shear keys have a huge influence on the shear capacity of precast column joints, but the increment of shear capacity due to such influence is limited over a range of shear key widths from 70 to 100 mm; (2) when the axial compression load ratio does not exceed 0.5, a joint’s shear capacity enhances gradually with the load ratio; (3) the expression developed in these experiments outperforms those recommended by four widely-used codes in giving the prediction of the shear capacity of column-to-column connections with shear keys, reinforcement across the joint and grouting.

Fragility-informed seismic design of multi-column bridge bents with post-tensioned concrete columns for accelerated bridge construction

Accelerated Bridge Construction (ABC) is playing an increasingly large role in bridge construction within urban centers due to faster installation, improved quality and lower cost. Concrete columns are prefabricated and connected together with footings and cap beams using either grouted splice sleeves, socket connections, or through post-tensioning. Precast unbonded post-tensioned (PT) concrete columns are protected from damage due to their ability to mitigate seismic demand through rocking. A numerical model is developed for rocking columns which is validated using published data. Seismic assessment of a two-column bridge bent constructed with precast PT concrete columns is carried out; column height-to-width ratio and ratio of initial posttensioning force to axial column capacity are selected as the assessment parameters. Performance limits are defined for the bridge model using non-linear pushover analysis. Probabilistic seismic hazard analysis is carried out using nonlinear time-history analysis for a set of eighty ground motions. The results show that PT concrete columns provide sufficient re-centering to the bridge bent so that it remains serviceable after a large earthquake. An ABC bridge bent with unbonded PT concrete columns is designed using the outcome of seismic fragility analysis. The seismic performance of the fragility-designed PT bridge bent is compared to that of a bent with conventional cast-in-place (CIP) concrete columns using nonlinear time-history analysis. The seismic performance of the ABC PT bridge bent using fragility analysis satisfied performance objectives similar to a monolithic CIP bent designed according to the latest seismic design codes; in addition, the residual drift of the PT bent was practically zero. The fragility-informed approach for designing ABC bridge bents constructed with unbonded PT concrete columns presented is expected to promote post-earthquake serviceability and functional recovery after a large earthquake.

Full-scale experimental investigation on the seismic performance of PC columns before and after repair of grouting defects

This research focused on investigating the influence of insufficient grouting on the seismic performance of precast concrete (PC) columns, connected using grouted sleeves, and validating the feasibility and reliability of the repair method for insufficient grouting. To realize these, five full-scale PC columns were tested under cyclic loads, including one specimen without grouting defects, two specimens with defect ratios of 45% and 60%, respectively, which were determined by previous cyclic test results of grouted sleeve connections (GSCs), and two repaired specimens which had initial defect ratios of 45% and 60%, respectively. The effects of defect ratios and repair actions were analyzed, and the test results indicated the following: 1) The bar slip dominated the failure of two specimens with defect ratios as expected, rather than the flexural failure mode for the specimen without defects. A rocking phenomenon was observed since the occurrence of bar slip, and the pinching phenomenon appeared for the corresponding hysteretic curves. The load-bearing, deformation and energy dissipation capacities were significantly lower than those of the specimens without defects. The increase in the defect ratio decreased the drift ratio associated with the bar-slip phenomenon, but the influence of the defect ratio on the seismic performance after the bar slip was negligible. 2) The bar-slip behavior was effectively prevented after the repair of insufficient grouting. Hence, the repaired specimens exhibited the expected flexural failure mode, and the load-bearing, deformation, and energy dissipation capacities were generally comparable with those of the specimen without defects. Rocking behavior and pinching phenomenon were not observed after repair. The negative influences of insufficient grouting were almost eliminated, thus validating the reliability of the repair method. The research outcome can serve as a reference for quality control of PC structures using GSCs.

Seismic performance of precast concrete column with different longitudinal reinforcement diameters under different lateral loading directions

To improve the installation efficiency of precast concrete (PC) columns with grouted sleeve connections, increasing the diameter of longitudinal rebar but keeping similar reinforcement ratio is a solution. To quantify the effects of longitudinal reinforcement diameter on the seismic performance of PC columns, eight full-scale reinforced concrete columns (six PC columns and two cast-in-situ) with identical concrete strength, reinforcement ratio, and stirrup ratio were designed and fabricated. The longitudinal reinforcement diameters varied from 18 mm to 32 mm. Moreover, considering majority of existing tests on PC column were subjected to relatively low axial compression ratio due to limitation of test facilities. Low-cyclic reversed loading tests were conducted with a high axial compression ratio of 0.6. Furthermore, to evaluate the bilateral loading effects, the loading direction was either horizontal or diagonal. Test results showed that the PC column achieved even higher lateral load capacity than corresponding cast-in-situ column regardless of the loading directions. Moreover, the lateral load capacity of the column under diagonal loading is generally lower than that under horizontal loading. However, the ductility and energy dissipation capacity of the columns under diagonal loading were higher than those under horizontal loading. Increasing the diameter of the longitudinal reinforcement will increase the lateral load capacity of the PC columns. This is because increasing the diameter of the longitudinal reinforcement required larger size of grouted sleeve, which further shortened the effective length of the column due to plastic hinge shifting. However, increasing the diameter of the longitudinal reinforcement may require greater bond strength between rebar and concrete and aggravate the bond failure pre-mature, which resulted in the less of deformation capacity and ductility, as well as energy dissipation capacity.

Seismic design and numerical assessment of shape memory alloy-restrained rocking precast concrete bridge columns

This paper introduces a class of shape memory alloy (SMA)-restrained rocking (SRR) bridge columns and numerically evaluates their response under lateral loading. SRR columns are low-damage precast concrete columns that are connected to their adjacent substructure components through two series of unbonded links, namely, SMA links and energy dissipation (ED) links. The SMA links, which are prestressed and made of superelastic Nitinol, provide the rocking joints with self-centering and dissipate a moderate amount of energy. The ED links, which are made of mild steel and are replaceable, supplement the hysteretic energy dissipation provided by the SMA links. The rocking joints are protected against concrete damage via steel jacketing and end steel plates. Following the introduction of three SRR column design variations, a displacement-based procedure is proposed for their effective seismic design. Nonlinear 3D finite element models are then developed to investigate the performance of the proposed columns under monotonic and cyclic lateral loading. Finally, a parametric study is conducted to examine the effective ranges of two major design parameters of SRR columns. The findings illustrate that the proposed SRR columns are capable of meeting their targeted performance objectives, i.e., avoiding damage under the displacement demands induced by a 2475-year seismic event, as well as providing significant self-centering and hysteretic damping.

Local damage of precast concrete columns with grout sleeve connections under contact detonation

Over the past several decades, the global terrorism is looming large and public buildings have become targets of terrorist bomb attacks. To obtain the blast performance of precast concrete (PC) columns with grout sleeve connections at the background of terrorist attacks, the contact detonation is concerned in this paper. An experimental program with six PC columns and one reinforced concrete column against contact detonation was conducted in a blast testing vessel, in which the effects of charge weight and location as well as connection type of columns on blast damage were studied. Then the finite-element-based (FE) numerical models were built up with LS-DYNA and validated with comparison of experimental results. In the FE model, blast load is simulated using multi-material Arbitrary-Lagrangian-Eulerian (MM-ALE) algorithm. After careful validation, the numerical models are extended to conduct parametric studies, including the effects of longitudinal and transverse reinforcement ratio, column section depth (or aspect ratio), charge weight and location, axial compression ratio on the blast damage of PC columns. Finally, curve-fitting-based models are derived to build up relationships between local damage sizes and the studied parameters, and then verified with part of numerical results. The results show that contact detonation destroyed all the concrete cover at the front face supporting the charge, and resulted in severe spall damage along the four corners and side faces, in which the corner connecting the side and rear face suffered larger damage than that connecting the side and front face. Moreover, the grout sleeves are able to mitigate the damage if the detonation is at the splicing segments. Increasing reinforcement ratio, section depth and axial compression ratio are able to reduce damage sizes, but the beneficial effect differs for the local damage at the column corners and front face.

A machine-learning-based model for predicting the effective stiffness of precast concrete columns

Predicting effective stiffness (ES) of precast concrete columns (PCCs) is an essential topic when PCCs are applied to structures in seismic zones. However, existing researches provide nearly no method especially for predicting the ES of PCCs, partly due to the high complexity of this issue. This study aims to firstly develop a machine learning (ML) model for predicting the ES of PCCs based on voting ensemble learning (VEL) algorithm which adopted different ML algorithms: support vector regression (SVR), random forest regression (RFR), and gradient boosting tree regression (GBTR) to respectively establish three base models. 177 flexural-dominant PCCs with various construction details were collected from the literature to assemble an experimental database, in which each specimen has 42 features. A ML model establishment proceeding was conducted, involving data preparation, feature selection, and hyperparameter tuning. Experimental verification was conducted to assess the VEL, SVR, RFR, and GBTR models, under the scenarios with/without feature selection. A comparison was conducted on the prediction performance between the existing empirical formulas and the VEL model with feature selection which was further interpreted using the combination of partial dependence analysis (PDA) and individual conditional expectation (ICE). Results show that the VEL algorithm can improve the accuracy and reliability of predicting the ES of PCCs. The VEL model with feature selection is proposed because it eliminates 21 negligible features and still presents far better prediction performance compared with the empirical formulas. The effect of each of the features considered in the proposed VEL model is recognized and depicted. Besides the four parameters considered in the existing formulas, another five parameters are also identified to have non-negligible influence on the ES of PCCs. Despite some limitations such as relatively insufficient number of data points, restricted range of input parameters, and lack of mechanical explanations, the proposed VEL model still firstly provides an accessible way to predict the ES of PCCs and can give inspiration for future researchers.

Equivalent stress-strain model of half grouted sleeve connection under monotonic and repeated loads: Experiment and preliminary application

The half grouted sleeve connection (HGSC) is widely adopted in the construction of precast concrete (PC) structures. So far, a few studies have been developed on the mechanical behavior of HGSC, however, efficient load-deformation models of HGSC are still scarce, which limits the numerical analysis of PC structures. In this study, therefore, an experimental study is undertaken to propose equivalent stress-strain models of HGSC under monotonic and repeated loads. The effect of rebar diameter, as well as the spliced length of rebar in the sleeve on the load-deformation behavior of HGSC is investigated with 60 specimens. Based on the test results, the failure mode, load capacity and strain of the spliced rebar is discussed. The results show that the failure mode of HGSC is mainly related to the spliced length of rebar. The capacity of HGSC is affected by the failure mode rather than the loading type. Moreover, a non-uniform distribution of bond stress of the spliced rebar is observed from the measured strains in the rebar. Finally, equivalent stress-strain models are proposed for the HGSC under monotonic and repeated loads. The model is established by revising the bi-linear stress-strain model of bare rebar, thus can be applied in the numerical study of PC members with high computational efficiency. The parameters of the models are calibrated with the test data obtained in the current study. A numerical simulation of a PC column with HGSC is developed to preliminarily verify the proposed model. The results show that the prediction of member deformation can be greatly improved by using the proposed model.

An experimental study on strength characteristics of replacement of fine aggregate with stone dust and coarse aggregate with demolished concrete waste

The report presents a comparative examination of the experimental results of the characteristics of fresh and cured concrete with various natural with recycled coarse and fine aggregate replacement ratios. Crushing leftover concrete from laboratory test cubes and precast concrete columns yielded recycled coarse aggregate. Stone dust was used in place of recycled fine aggregate. One of the most significant components of a reinforced structural part is concrete. Concrete has an inextricable influence on reinforced concrete constructions. Concrete that isn't strong enough puts the entire structure in harm. Many structures nowadays fail as a result of a lack of strength. The mechanical properties of concrete changed by stone dust as a fine aggregate replacement material are investigated in this work. A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse and fine aggregate are presented in the paper. Recycled coarse aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Recycled fine aggregate was replaced by stone dust. Concrete is one of the most important components in reinforced structural member. In reinforced concrete structures concrete have some inseparable influence. Lacking in concrete strength endanger the whole structure. Now a day it is seen that many structures fails due to lack of strength. In this paper investigate experiment is reported on the mechanical properties of concrete modified by stone dust as replacing material of fine aggregate and demolished concrete waste as replacing material of coarse aggregate and a study is conductto determine the engineering properties of compressive strength, tensile strength, flexural strength and water absorption capacity of partially replacement of natural sand and natural aggregate. In recent days the demand of river sand is increasing due to its lesser availability. Hence the practice of partially replacing river sand with stone dust is taking a tremendous growth. Due to critical stage of natural aggregate the availability of demolished concrete as recycled aggregate. Using discarded concrete as recycled aggregate conserves natural aggregate, lowers landfill impact, reduces energy use, and potentially saves money. The materials of the future are recycled aggregate. Stone dust and destroyed concrete waste were used to replace 25 percent, 50 percent, 75 percent, and 100 percent of fine and coarse aggregate, respectively. After a 28-day curing period, concrete samples (cubes, cylinders, and beams) are cast and evaluated. To produce the effect on mortar, several members were built utilising the above percentage. Modified concrete is compared to regular concrete in terms of strength. The strength parameters of concrete employing stone dust as fine aggregate and demolished concrete debris as coarse aggregate are observed to increase in compressive strength, flexural strength, and tensile strength. It was discovered that the concrete may be used as structural members in buildings and other structures.

Seismic Performance of Precast Concrete Frame with Innovative Assembly Pattern

ABSTRACT A novel precast concrete (PC) frame with an innovative assembly pattern and optimised connection locations was proposed and evaluated. The PC column components were connected by extrusion sleeves and/or U-type reinforcement ferrules to realise cost-effective, efficient, and reliable assembly. Quasi-static cyclic loading tests and finite element analyses were conducted on a cast-in-place (CIP) frame and three PC frames with different connection types. The PC frames exhibited higher lateral stiffness and load bearing capacities than the CIP frame, as well as similar energy dissipation capacities. The PC frames employing the extrusion sleeve connections in the beam exhibited the best seismic performance.

Precast concrete column base with replaceable energy dissipation connectors: Quasi‐static tests and numerical research

AbstractA type of precast concrete column base with replaceable energy dissipation connectors (REDCs) is proposed in this study. The bottom of the column is reinforced with a square steel tube. REDCs can transfer the bending moment of the column base during frequent earthquakes and yield to dissipate most of the inputted seismic energy during major earthquakes. Several raised steel stoppers are arranged around the sides of the column base to limit lateral slippage. The load‐resisting mechanism, construction technology and post‐earthquake repair methods of the column base are introduced. Five quasi‐static tests were carried out on a full‐scale test specimen, in which the experimental variables include the axial compression ratio of the column and the size of the REDCs. The test results show that the damage was concentrated in the REDCs while the precast column suffered minor damage. The REDCs fractured after dozens of cycles at large lateral drift ratios, effectively exerting their excellent low‐cycle fatigue performance. Plump and stable hysteretic curves and bilinear skeleton curves were obtained in test results. The curves before and after seismic rehabilitation are similar. Furthermore, a simplified numerical analysis model of the column base is established using OpenSees. The hysteretic curves and skeleton curves obtained by simulation agree with the test results.

Experimental and numerical investigation on seismic behavior of detachable precast concrete column joints with bolted flange plate

In order to achieve rapid erection, a bolted flange plate column-column connection was proposed for concrete frames in this paper, which have been conventionally used in steel structure to transfer axial tension and bending moment. This paper presents an experimental and numerical work for seismic behavior of this detachable precast concrete column joints with bolted flange plate. Four specimens were tested under constant axial compression and horizontal cyclic reversed loading to research the reliability of this joint, including one cast-in-situ column and three precast column joints with bolted flange plate. The failure modes, hysteretic curves, skeleton curves, ductility and energy dissipation capacity are presented. The test results indicate that joint with a bolted flange plate would change the failure mode of the concrete column. A reliable welding between rebars and flange plate plays an important role in seismic performance of precast column. When the welding damage does not take place, the bearing capacity, ductility and energy dissipation capacity of concrete columns would not be affected by the column-column joint. In addition, finite element model was validated and parametric analysis was conducted to study the behavior of detachable precast concrete column joints with bolted flange plate under cyclic loading.

Tensile and flexural behaviors of connections between steel beam and concrete-encased-and-filled steel tube column

Concrete-encased-and-filled steel tube (CEFT) columns with a circular tube section can be potentially used for hollow precast concrete (PC) constructions, in which thin PC encasement is used to reduce the lifting weight of a large PC column. In the present study, connection methods were studied for steel beam-CEFT column joints with the thin concrete encasement. Two sets of testing were performed focusing on the local behavior of the connection: 1) monotonic tension test for beam flange-column connections, and 2) cyclic loading test for beam-column joints. In the first test, the local out-of-plane behavior of the flange plate-tube connections and the associated damage mode of the concrete encasement were identified. The load-deformation relationships of the test specimens were evaluated by nonlinear finite element analysis. Based on the results, exterior beam-column joint specimens were designed, and the flexural behavior of the connections was verified under cyclic loading. The joint specimens were strengthened with connection methods such as tension bars, thick steel tube, and vertical continuity plate, inducing the beam failure. In particular, the thick tube and vertical continuity plate were effective in restraining the concrete damage. The tensile and flexural strengths of the test specimens were evaluated using design equations.