Abstract
This study conducted an experiment and numerical analysis to investigate structural performances of precast
concrete-steel composite double walls (PSDWs) with discontinuous steel connectors (DSCs) subjected to out-of-plane loading,
where those DSCs are uniquely adopted for better stability in erection, safe installation, better formwork to resist lateral pressure
induced by fresh cast-in-place (CIP) concrete, and subsequent improved composite action, not for strength design purpose. Total
six specimens were fabricated for shear and flexural testing, where the connection details between two precast concrete (PC)
wall panels to secure composite performances with CIP concrete were set as a key testing variable. The flexural and shear
behaviors and crack patterns of the test specimens were compared and analyzed in detail, and the behavioral characteristics of
PSDWs were identified through nonlinear sectional analysis and detailed finite element analysis. The test and analysis results all
showed that the DSCs can provide significant improvement in the flexural performance of PSDWs; however, it is recommended
not to reflect their contribution for conservative design. In addition, it appeared that the shear behavior of PSDWs can also be
significantly enhanced by DSCs, but shear resistance of DSCs is not fully reliable unless the DSC members are continuously
placed in the longitudinal direction.
Key Words
concrete-steel composite; double wall; finite element analysis; precast concrete
Address
Sun-Jin Han:Department of Architectural Engineering, Jeonju University, 303, Cheonjam-ro, Wansan-gu, Jeollabuk-do, Republic of Korea
Min-Su Kim:Department of Architectural Engineering, Chungbuk National University, Chungdae-ro 1, Seowon-gu, Chungcheongbuk-do, Korea
Inwook Heo:Urban Safety and Security Research Institute, University of Seoul, 163 Seoulsiripdae-ro, Dongdaemun-gu, Soeoul 02504, Korea
Won-Jun Lee:Department of Architectural Engineering, Chungbuk National University, Chungdae-ro 1, Seowon-gu, Chungcheongbuk-do, Korea
Deuckhang Lee:Department of Architectural Engineering, Chungbuk National University, Chungdae-ro 1, Seowon-gu, Chungcheongbuk-do, Korea
Abstract
This study investigates the performance of steel frame connections subjected to blast loading using finite element
analysis (FEA). The yield line theory was employed to design the connection end plate, and nine different connection
configurations were analyzed by modifying the base model. These configurations explored variations in end plate thickness, bolt
diameter, and the presence of stiffeners and doubler plates. The significance of this research lies in its potential to improve the
safety and resilience of structures against blast loads, which are critical for protecting infrastructure and human life in extreme
events. The results revealed that the base model exhibited a brittle failure mode with a maximum displacement of 210 mm and
failure through bolt shearing and end plate rupture. Increasing the end plate thickness in Model 2 eliminated end plate failure but
led to bolt yielding. Models incorporating stiffeners (Models 4 and 5) improved energy absorption but caused stress
concentrations in the column, while doubling plates in Model 7 enhanced energy absorption in both the beam and column,
mitigating bolt failures and achieving a balance between strength and ductility. Compared to the Model 1, Models 7, 8, and 9
demonstrated superior performance in reducing the column's proportion of the total energy absorption, with a reduction in plastic
deformation energy absorption by the column (ratios of 0.37, 0.28, and 0.27, respectively) compared to the base model (0.4).
Moreover, the results provide actionable insights for developing blast-resistant steel frame design guidelines, particularly
emphasizing the integration of doubling plates and stiffeners to enhance safety and resilience. This work has significant
implications for improving the performance of steel structures in critical infrastructure applications.
Key Words
complex networks; mathematical simulation; mechanical behavior; nanotechnology
Address
Mehdi Ebadi-Jamkhaneh:Department of Civil Engineering, School of Engineering, Damghan University, Damghan, Iran
Abstract
This study investigates the feasibility and effectiveness of a friction damper made of brake pads, high-strength bolts,
and a heavy-duty coil spring. It is positioned in the middle of a steel bracing to dissipate earthquake energy. To evaluate the
effectiveness of the proposed damper, its mechanical behavior is evaluated through finite element analysis, and an analytical
model is established for structural analysis and design. The analytical model of the damper is developed using SAP2000
software and is compared with the FE model generated in Ansys Mechanical software. Bayesian optimization technique with
Gaussian process is employed to determine the minimum number and optimum locations of the dampers to satisfy a given limit
state with minimum cost. The analytical model and the optimum design technique are applied to a 5-story reinforced concrete
(RC) structure to assess its performance before and after retrofit for the maximum considered earthquake (MCE) conditions. The
seismic performance is thoroughly evaluated regarding maximum interstory drift, residual displacement, and energy dissipation
capability. Overall, the results demonstrate the efficiency of the proposed friction damper and optimum design technique in
safeguarding structures against seismic loads.
Key Words
Bayesian optimization; friction dampers; nonlinear time history analysis; seismic retrofit
Address
Sajjad Akbara:Department of Civil and Architectural Engineering, Sungkyunkwan University, Suwon, Korea
Mohammad Noureldin:Department of Civil Engineering, Aalto University, Otakaari 1, Espoo, Finland
Jinkoo Kim:Department of Civil and Architectural Engineering, Sungkyunkwan University, Suwon, Korea
Abstract
This paper presents a comprehensive numerical investigation into the flexural behaviour of hybrid high-strength
steel (HSS) I-beams subjected to major axis bending. Initially, finite element (FE) models were developed and validated against
available experimental results for welded homogeneous and hybrid HSS I-beams, employing a methodology consistent with
prior research. These validated FE models were subsequently employed for parametric studies, covering a broad range of cross
sectional slenderness for hybrid HSS I-beams. The results from FE models reveal that, to meet rotation capacity requirements,
more stringent Class 1 slenderness limits for both the outstand flange in compression and the internal web in bending are
necessary. Further, slenderness limits are proposed to facilitate plastic design of hybrid HSS sections under bending.
Furthermore, comparisons between Class 2 and Class 3 slenderness limits and the codified European standards, revealed
inadequacies for hybrid HSS beams. Consequently, new limits are recommended for classifying various cross-sections.
Additionally, the applicability of the design equations in Eurocode (EN 1993-1-1), Direct Strength Method (DSM), and
Continuous Strength Method (CSM) for hybrid HSS I-beams has been assessed, demonstrating increased variability. Hence,
modified DSM and CSM formulations specifically tailored for hybrid HSS I-beams are proposed. The proposed equations are
found to provide conservative and reliable predictions, thus recommended for inclusion in design standards.
Key Words
continuous strength method; direct strength method; flexural strength; four-points bending; hybrid HSS I
beams; slenderness limit
Address
Keshav Saini:Department of Civil and Infrastructure Engineering, Indian Institute of Technology Jodhpur, India, Jodhpur - 342030
Ricky Lalthazuala:Department of Civil Engineering, National Institute of Technology Mizoram, India, Mizoram – 796012
Tekcham G. Singh:Department of Civil and Infrastructure Engineering, Indian Institute of Technology Jodhpur, India, Jodhpur - 342030
Abstract
Connections are crucial in structural systems, particularly in steel structures, as they play a vital role in maintaining
the integrity and stability of the entire system. This study aims to determine the optimal dimensions for four types of end plate
connections, utilizing advanced optimization techniques: Teaching-Learning-Based Optimization (TLBO), Particle Swarm
Optimization (PSO), and Snake Optimizer (SO). The primary objective is to minimize costs while satisfying mechanical
constraints on bending moment and initial stiffness, ensuring structural safety and integrity. The design variables under
consideration include the dimensions and thickness of the end plates, bolt diameters, and the placement of bolts. To accurately
assess the connection's performance, the bending moment and rotational stiffness were calculated using the "component
method" outlined in Eurocode 3, Part 1-8. The computational analysis was conducted using MATLAB software, which
facilitated the modeling and optimization processes. The results demonstrated strong alignment with prior research outcomes,
aligning closely with findings from previous research, thereby validating the effectiveness of the chosen optimization methods.
The proposed optimal design not only enhances reliability compared to earlier studies but also achieves a significant reduction in
connection costs—up to 56%. This improvement underscores the potential of using advanced optimization techniques in
structural design, offering a pathway to more efficient and cost-effective engineering solutions. This study offers practical
contributions to the design and optimization of steel connections, promoting enhanced structural performance and economic
viability in construction practices.
Key Words
bolted end-plate connections; component method; optimization algorithm; steel moment connection;
structural optimization
Address
Ali Sadeghi:Civil Engineering Department, University of Sistan and Baluchestan, Zahedan, Iran
Mohammad Reza Sohrabi:Civil Engineering Department, University of Sistan and Baluchestan, Zahedan, Iran
Seyed Morteza Kazemi:Department of Civil Engineering, Kashmar Branch, Islamic Azad University, Kashmar, Iran
Abstract
This study investigates the fire resistance of partially encased composite (PEC) members through experiments and
finite element (FE) analysis. Fire tests were conducted on three T-shaped PEC beams and six rectangular PEC columns, each
with fire-proof coating, exposed to the ISO 834 standard fire curve. Results showed that all beams experienced flexural
deformation and concrete cracking, and satisfied the two-hour fire resistance requirement. FE models were developed to
simulate temperature development, distribution, and thermo-mechanical behavior, with numerical results matching experimental
outcomes. A parametric study was conducted to investigate the effects of coating thickness, section dimensions, and load ratio on
temperature development and fire resistance. It was found that increasing the coating thickness from 7.0 mm to 11.0 mm
reduced the peak temperature by approximately 150°C after 3 hours of fire exposure. Additionally, the load ratio significantly
impacted the fire resistance of PEC beams, while section dimensions had minimal influence. Based on these findings, a practical
design method for predicting the load capacity of PEC beams under elevated temperatures was proposed, showing good
agreement with experimental and FE results.
Key Words
fire-proof coating; fire resistance; fire tests; numerical simulation; partially encased composite members;
practical design method
Address
Hao Tang:College of Civil Engineering, Tongji University, Shanghai 200092, China
Shouchao Jiang:1)College of Civil Engineering, Tongji University, Shanghai 200092, China
2)State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China
Yanbo Wang:College of Civil Engineering, Tongji University, Shanghai 200092, China
Zhengjun Liu:College of Civil Engineering, Tongji University, Shanghai 200092, China
Shaojun Zhu:College of Civil Engineering, Tongji University, Shanghai 200092, China
