Editorial on the Structural Reliability, Resilience, and Design of Buildings Against Multi-Hazards

1. Introduction

Against the backdrop of increasing seismic threats to cultural heritage globally, the vulnerability of historical masonry structures demands urgent attention. The nonlinear material behavior, structural heterogeneity, and time-sensitive conservation challenges necessitate innovative approaches to address these issues. This Special Issue compiles 14 pioneering studies that integrate simplified numerical modeling, smart monitoring, and advanced retrofitting to bridge the gap between engineering efficiency and heritage preservation. Collectively, these works establish a framework for rapid post-disaster decision-making, driving civil engineering toward the resilient and intelligent conservation of cultural assets in seismically active regions.

2. Overview of the Contributions

Zheng et al. (Contribution 1) developed an XGBoost-based surrogate model for the rapid seismic response assessment of building clusters (reducing the computation time by >90% with R² > 0.99) and a Bayesian probabilistic model for earthquake-induced debris width prediction, which reduced the prediction uncertainty by 60% and was validated via a campus case study showing 45% road blockage.

Demircan (Contribution 2) developed a simplified finite element (FE) approach to rapidly assess seismic vulnerability in the partially collapsed historic Habibi Neccar Mosque after the 2023 earthquakes. Using linear dynamic analysis, the study identified critical tensile stresses at dome–arch joints and vaults as primary failure triggers, exacerbated by soil amplification and out-of-plane wall deformations. The method prioritized computational efficiency, validated against field damage patterns, and offers a practical tool for emergency stabilization decisions in cultural heritage conservation.

Zhong et al. (Contribution 3) demonstrated, using shaking-table tests, that epoxy-bonded carbon-fiber cloth enhances RC Diaojiaolou seismic resilience, increasing the collapse PGA by 49.5% and redefining the damage into three phases: DS, YS, and PS. The natural periods and acceleration/displacement increments followed exponential laws, with carbon fiber minimizing the acceleration impact at the stilt layer (I) and optimizing the displacement resistance at the base for the unreinforced and stilt layer (I) for reinforced structures, providing a low-cost solution for mountain buildings in China’s minority ethnic regions.

Jin et al. (Contribution 4) developed a nonlinear analytical framework using asymptotic methods to investigate the in-plane stability of pin-ended circular arches under uniform vertical loads. The parameter perturbation method effectively analyzed the snap-through buckling of shallow arches, with fifth-order solutions proving sufficiently accurate. The results demonstrated that the axial load components significantly influenced arches with large modified slenderness ratios or large rise-to-span ratios. For anti-symmetric buckling, the second-order WKB solution yielded lower critical loads than the third-order solution, providing a conservative estimate. The study confirmed the classical solutions’ reliability for shallow arches with small rise-to-span ratios but highlighted the necessity of accounting for axial load effects in deep arches. The nonlinear bending moments consistently exceeded the linear predictions across all geometries.

Li et al. (Contribution 5) developed an innovative four-footstool GFRP connector for precast recycled concrete thermal insulation panels and experimentally evaluated its mechanical performance against traditional Thermomass MS connectors. The pull-out, shear, and flexural tests compared both connector types in conventional and recycled concrete. The results showed the GFRP connector increased the pull-out capacity by 14.8% and the shear resistance by 20.6% in recycled concrete, while the flexural strength improved by 16.5%, with more uniform crack distribution. A reduction factor γ = 0.68 was proposed to simplify the flexural design calculations, validated by close alignment with the experimental values. Recycled concrete demonstrated comparable performance to conventional concrete when paired with GFRP connectors, supporting sustainable construction applications.

Based on the cyclic loading tests of four prefabricated HDRPC joints, one cast-in-place HDRPC joint, and one normal concrete joint, Li et al. (Contribution 6) demonstrated that HDRPC significantly enhanced the seismic performance. The HDRPC increased the joint bearing capacity by 17.8% and the displacement ductility by 33.3%, reduced the crack width and shear deformation in the joint core, and allowed wider stirrup spacing, while outperforming normal concrete joints with denser reinforcement. The grouted sleeve connection ensured reliable force transfer, and a proposed crack-resistance equation aligned closely with the test results, supporting HDRPC’s application in sustainable prefabricated structures.

Based on a seismic reliability framework, Li et al. (Contribution 7) proposed a collapse fragility analysis method for RC frame structures, considering the capacity uncertainty, utilizing incremental dynamic analysis to identify collapse points and the fractional exponential moments-based maximum entropy method to fit distributions of maximum inter-story drift ratios. They defined collapse via the stiffness degradation or MIDR thresholds, calculated the failure probabilities using a combined performance index, and fitted the fragility curves with a shifted generalized lognormal distribution. The results showed that accounting for the capacity uncertainty reduced the collapse probability, increasing the median collapse resistance by 13.2% and 87.3%, compared to the deterministic MIDR limits of 1/25 and 1/50, respectively, which demonstrated SGLD’s superior accuracy over traditional lognormal models.

An et al. (Contribution 8) proposed a novel graded-yielding metal self-centering brace to minimize residual deformation in structures under strong earthquakes and achieve graded seismic protection. The brace utilized X-shaped steel plates and U-shaped steel plates for staged energy dissipation, combined with pre-compressed disc springs for self-centering. They derived a theoretical restoring force model and validated it using ABAQUS finite element simulations under low-cycle loading. The numerical results closely matched the theoretical model, demonstrating flag-shaped hysteresis curves, excellent energy dissipation, staged yielding, and effective self-centering. Parametric studies showed that increased disc spring pre-compression improved self-centering, while thicker steel plates enhanced energy dissipation but increased residual deformation.

Zhang et al. (Contribution 9) proposed and tested a composite damper with yielding reserve stiffness to address large structural deformations under seismic limit states. The YRSD combined a friction unit and a metal yield unit in series to provide multi-stage energy dissipation and yielding reserve stiffness. Low cyclic loading tests on three specimens with varying X-plate thicknesses and bolt preloads demonstrated full hysteresis curves, controllable multi-stage energy dissipation, and hardening post-yield stiffness. Doubling the bolt preload increased the friction energy dissipation by 53.8% and the envelop hysteresis area by 56.1%. Increasing the X-plate thickness by 2 mm raised the resistance by 26.2% and the post-yield stiffness by 37.9%. The numerical simulations validated the experimental results with errors under 10%.

Ye et al. (Contribution 10) developed a multiscale damage identification method for beam-type structures using node curvature. They derived a damage index based on bending moment–curvature relationships and the assumption that micro-damage minimally affects stress redistribution. Wavelet analysis denoises signals before solving linear matrix equations via singular value decomposition. Laboratory tests on a simply supported beam verified the sensitivity to a 1% stiffness reduction. Field validation using a continuous beam bridge’s multiscale FE model confirmed precise damage localization in small-scale elements and noise resistance with under 10% interference. The method effectively identified damage location/severity in both numerical and real-world scenarios, demonstrating robustness for structural health monitoring.

Bai et al. (Contribution 11) established seven 3D finite element models to investigate the influence of shallow soil reinforcement width and depth on the horizontal bearing capacity of a single pile in soft soil. The models, validated against field tests, analyzed reinforcement widths of 2D, 3D, and 4D and depths of 0.1 L, 0.2 L, and 0.3 L. The results showed that reinforcement significantly increased the horizontal bearing capacity by 83.0%, 104.3%, and 224.4% for increased widths and by 224.4%, 361.3%, and 456.8% for increased depths, respectively. The bending moments and deformations decreased with greater width, while the capacity gains diminished nonlinearly with a depth beyond 1.5D, indicating an optimal depth and advising against unevaluated deep reinforcement.

Chen et al. (Contribution 12) investigated the seismic performance of high-strength steel frames with Y-eccentric braces using a variable replaceable link. Parametric variations included the link’s energy-dissipating region length, steel grade, span, and total link length. The results showed that reducing the span and using higher-grade steel enhanced the ductility and ultimate bearing capacity by up to 20.7%, while shorter energy-dissipating regions increased the shear force by 8.3%. An optimal link length improved the stiffness and energy dissipation, whereas an excessive length reduced the capacity and complicated the post-earthquake replacement. The plastic strain concentrated in the designed energy-dissipating zone, validating the replaceable link’s effectiveness for targeted damage and easier repair.

Mao et al. (Contribution 13) proposed a kinetic energy distribution model for a rocking rigid body within a mass point system to refine the collision restitution coefficient calculation. Their model divided the collision into three stages: incorporating energy dissipation in the first two stages to determine total kinetic energy and redistributing the remaining kinetic energy in the third stage. This yielded an analytical solution for the coefficient. They validated the model using experimental and statistical data, finding significantly reduced errors and a correlation coefficient exceeding 0.9 compared to the classical Housner model, particularly for larger masses. The model provided a more reliable approach for the seismic analysis of rocking structures.

Ma et al. (Contribution 14) investigated the response modification factor (R) for high-strength steel frames with D-eccentric braces using the incremental dynamic analysis method. They designed 18 structural models varying in stories (4, 8, 12), link lengths, and steel strengths. The IDA method determined the R, displacement amplification factor (C_d), and overstrength factor (R_Ω) for each model. The results showed R values of approximately between 8.2 and 10.0, with effects of the story number, link length, and steel strength on R and C_d being complex and sometimes inconsistent. The study provided essential coefficients for the seismic design applications of D-HSS-EBFs.

3. Conclusions

These studies provide critical design coefficients, refine computational methodologies, and establish new benchmarks for earthquake-resistant infrastructure. The findings significantly advance the frontiers of structural engineering, offering actionable insights for resilient and sustainable construction in seismic-prone regions.