Abstract
This paper proposes an effective procedure for evaluating the influence of uncertain input parameters on
the dynamic responses of the steel structures. Uncertainty in material properties, geometrical characteristics, and the
mass density of steel structure involved with each member considered the individual random field in the entire frame
structure under different seismic loads. The Monte Carlo simulation (MCs) is effectively integrated with the
advanced nonlinear inelastic dynamic analysis program to thoroughly account for second-order effects. The Hilber
Hughes-Taylor method associated with the Newton-Raphson balance iterative algorithm is used to solve the
nonlinear equations of motion. The results indicate that uncertain input parameters significantly affect the dynamic
response of steel structures, with variations in geometrical dimensions being the most critical. A numerical example
demonstrates the effectiveness of stochastic steel frame analysis under dynamic loads, revealing a notable difference
in vibration modes of 30-44% compared to deterministic analysis, thereby providing valuable insights into the
uncertainty in advanced structural analysis.
Abstract
This study numerically investigates the impact resistance of circular steel tubes coated with polyurea elastomer under low-velocity drop-weight impact. A total of 144 finite element (FE) models of composite tubes and 24 uncoated steel tubes were established to systematically analyze the effects of polyurea thickness, spray position, length-to-diameter ratio (α), diameter-to-thickness ratio (γ), and impact energy (Eₐ). The failure modes are classified into three types: local denting (L), global bending (G), and coupled deformation. The latter refers to a combination of L and G, further distinguished as “L+G” (local denting dominant) or “G+L” (global bending dominant) based on which component contributes more to the total displacement. This method was developed using a modified equal-area axis method combined with bottom bending angles. Results demonstrate that double-sided polyurea coatings (4 mm thickness) most effectively suppress radial bulging and enhance energy absorption, particularly under high-energy impacts (Eₐ ≤ 11.2 kJ). The Discussion section validates failure modes in bare steel tubes using the P₀/λPₓ ratio and proposes a new dimensionless criterion incorporating coating parameters to accurately predict failure modes in composite tubes. The parametric analysis provides fundamental insights for optimizing polyurea reinforcement strategies in industrial pipelines susceptible to accidental impact.
Address
Shiqi Zhao:College of Civil Engineering and Architecture, Shandong University of Science and Technology,
Qingdao 266590, China
Peng Deng:1)College of Civil Engineering and Architecture, Shandong University of Science and Technology,
Qingdao 266590, China
2)Shandong Provincial Key Laboratory of Civil Engineering Disaster Prevention and Mitigation, Shandong
University of Science and Technology, Qingdao 266590, China
Jiacheng Liu:College of Civil Engineering and Architecture, Shandong University of Science and Technology,
Qingdao 266590, China
Jian Guo:College of Civil Engineering and Architecture, Shandong University of Science and Technology,
Qingdao 266590, China
Zhongyi Zhu:College of Civil Engineering and Architecture, Shandong University of Science and Technology,
Qingdao 266590, China
Abstract
Steel frames are widely used because of their light weight, high ductility, and construction convenience.
However, existing approaches for ultimate load-carrying capacity analysis struggle to balance accuracy and
computational efficiency. The plastic-zone method provides high accuracy but low efficiency, whereas the
conventional first-order plastic-hinge method is computationally efficient but neglects the influence of axial force on
plastic hinge development, overestimating the structural ultimate load-carrying capacity. To address these issues, this
study proposes a generalized plastic-hinge method based on a generalized yield criterion. An equivalent
homogeneous yield function is introduced to construct an element-level load-carrying ratio, which captures the
coupled effects of the axial force and bending moment on plastic hinge development while preserving proportional
scaling with the external load. This formulation enables efficient and accurate evaluation of the ultimate load-carrying
capacity. Subsequently, a small set of ultimate load-carrying capacity samples generated by the proposed method is
used to reconstruct an explicit limit-state function via a support vector machine optimized by the particle swarm
optimization for the reliability analysis. The numerical results demonstrate that the proposed method can accurately
and reliably evaluate the structural ultimate load-carrying capacity. The reliability results obtained from the
reconstructed limit-state function are in excellent agreement with those obtained from the Monte Carlo Simulation.
Key Words
steel frame structures; generalized plastic-hinge method; proportionality property; ultimate
load-carrying capacity; support vector machine; reliability analysis
Address
Da Lian Bai:College of Civil and Mapping Engineering, Guilin University of Technology at Nanning, Nanning, 530001,
China
Yan Xue Liao:College of Civil and Mapping Engineering, Guilin University of Technology at Nanning, Nanning, 530001,
China
Zhi Yi Wu:College of Civil and Mapping Engineering, Guilin University of Technology at Nanning, Nanning, 530001,
China
Jia Liang Wang:College of Civil and Mapping Engineering, Guilin University of Technology at Nanning, Nanning, 530001,
China
Cun Peng Liu:College of Civil and Mapping Engineering, Guilin University of Technology at Nanning, Nanning, 530001,
China
Abstract
The seismic risk and vulnerability of multistorey reinforced concrete (RC) structures built in different
eras for various functions vary significantly. However, seismic risk analysis of regional RC building portfolios
considering age and diverse functional requirements has rarely been conducted. This paper innovatively considers
aging and structural-functional requirements, updating the traditional probabilistic earthquake risk and hazard model.
Using the Chinese macroseismic intensity standards and seismic hazard model developed here, a novel monitoring
seismic intensity bundle with time histories and spectral curves considering 270,000 acceleration values was
generated (nine real stations of the Luding earthquake in Sichuan Province, China, on September 5, 2022 were used).
This paper innovatively uses monitoring intensity as an auxiliary scale and Chinese macrointensity as the main
quantitative scale to estimate the vulnerability level of 622 RC buildings surveyed after the Wenchuan earthquake in
Sichuan, China, on May 12, 2008. A structural seismic vulnerability statistical model considering age and functional
requirements is established. The damage to low-height reinforced concrete (LRC) and medium-height reinforced
concrete (MRC) building clusters with different ages and functional requirements varies according to the intensity
zones. Using mathematical statistics and failure mode analysis methods, a comparison of structural seismic
vulnerability considering functional and age effects was generated. In particular, a structural seismic vulnerability
plane model considering age and functional requirements was generated via cumulative damage probability (CDP)
and two-dimensional plane density estimation. An updated seismic vulnerability index (USVI) function was also
proposed, and USVI stripe zones and curves considering structural failure datasets were developed.
Key Words
age and functional requirements; earthquake risk mitigation strategies; multistorey reinforced
concrete structure; seismic risk and vulnerability model; updated seismic vulnerability index curve
Address
Si-Qi Li:1)Key Laboratory of Earthquake Engineering and Engineering Vibration, Institute of Engineering Mechanics,
China Earthquake Administration; Key Laboratory of Earthquake Disaster Mitigation, Ministry of Emergency
Management, China
2)School of Civil Engineering, Heilongjiang University, No. 74, Xuefu Road, Harbin City, China
Lin-Lin Zheng:School of Civil Engineering, Heilongjiang University, No. 74, Xuefu Road, Harbin City, China
Nicola Chieffo:School of Computing and Engineering, University of Huddersfield, Huddersfield, United Kingdom
Abstract
The seismic performance of rack storage structures is mainly governed by the beam-to-upright
connections, which are highly flexible and show considerable stiffness and strength degradation, along with pinching
behavior. To address these vulnerabilities, a steel hysteretic damper is proposed which can be installed at these joints
to improve seismic performance and energy dissipation. The damper consists of an L-shaped steel plate with a
tapered section which acts as a fuse, yielding under rotational deformation at the joint. The mechanical behavior of
the damper is theoretically formulated for the design purpose and it incorporates the derivation of slope-deflection
equations for tapered members. The accuracy of the formulation is verified by comparing its prediction with a
detailed finite element model in Ansys and OpenSees. The effects of geometric imperfections and buckling is also
investigated using a probabilistic approach and finite element simulations. To further investigate the effectiveness of
the proposed device, an experimental test on a beam-to-upright connection from a rack subassembly subjected to
cyclic loading is simulated and validated in OpenSees. The damper's model is then applied to the validated system,
and the cyclic behavior before and after retrofit is compared in terms of hysteretic response and energy dissipation.
Results show that the proposed energy dissipation device can enhance stiffness, capacity and energy dissipation
capability of the joints. The theoretical formulation, analysis modeling approach and simulations presented in this
study provide a detailed insight into seismic behavior of steel rack storage structures.
Abstract
Conventional seismic assessment often treats components in isolation, obscuring how local damage
propagates through a frame and reduces reliability. This paper proposes a performance-based system-reliability
framework that ranks component criticality by coupling global reliability with connectivity and load-path
redundancy. The first contribution is an explicit integration of Performance-Based Design and Load and Resistance
Factor Design. Multi-state demand–capacity checks at Immediate Occupancy (IO), Life Safety (LS), and Collapse
Prevention (CP) are mapped into a system reliability space, allowing design targets and acceptance criteria to be set
and verified with a single, coherent set of reliability measures. The second contribution is a Failure Gate methodology
for system criticality. Combinatorial limit-state functions generate a system reliability index; a Dynamic Redundancy
Measure quantifies the loss of reserve capacity relative to the intact system; and an Element Reliability Matrix
(EMR) captures interaction and topology, including series and parallel effects, as well as weak seams. The gate
model, consistent with plastic-hinge mechanics, removes a member only when both ends lose the ability to transfer
moment, thereby avoiding penalties for partially functional elements. The resulting criticality index combines
reliability, redundancy, and connectivity losses to yield transparent, reproducible rankings. Applications to 3-, 9-, and
20-story steel moment frames demonstrate that the loss of lower-story columns incurs the most significant reliability
penalties and that failure trajectories are essentially topology-driven rather than record-specific. The method scales
with height, guides retrofit where reliability loss is most acute, and clarifies target reliability assignment by linking
component damage to system performance.
Key Words
criticality; fragility curves; hysteresis behavior; incremental dynamic analysis; reliability index;
system reliability
Address
Seyed Hooman Ghasemi:Department of Civil, Construction, and Environmental Engineering, University of Alabama at Birmingham, Birmingham, AL 35205, USA
Farshad Dorri:Department of Civil Engineering, Islamic Azad University, Qazvin Branch, Qazvin, Iran
Devin Huber:American Institute of Steel Construction, Chicago, IL, 60601, USA
open access
