Member-level damage identification and FRP strengthening for semi-rigid jointed spatial lattice structures

Shu-Hui Huang , Wen-Jie Li , Ze Yang , Ming-Liang Zhu , Zhi-Wei Shan , Kun Liang , Daniel Ting-Wee Looi

Abstract

Lattice shells rely on axially dominated members where semi-rigid joints are common, yet most damage detection frameworks remain global-level and do not provide design-ready residual capacity at the member level. This study proposes a one-frequency damage quantification method that infers flexural stiffness reduction from the first natural frequency under elastic end restraints, and a semi-rigid–aware capacity model that modifies the Perry–Robertson formulation via a corrected normalized slenderness and a load-correction coefficient τ expressed as a linear function of the dimensionless stiffness ξ=kL2/(EI). The approach is closed with a design workflow that maps damage severity to required FRP retrofit (type, ply number, fiber angle) through equivalent-section transformation. Parametric FEM and external tests demonstrate that: (i) the proposed identification reproduces stiffness loss with errors typically below 2% for semi-rigid and fixed ends; (ii) neglecting joint semi-rigidity yields stability-coefficient errors exceeding 10% for the normalized slenderness ratio higher than 1.3. whereas the modified equation limits errors to ≤2–6% with R2=0.98; and (iii) the retrofit workflow predicts axial capacity gains consistent with validated FEM across 175 cases. The framework enables measure-once member-level diagnosis and design-oriented rehabilitation of lattice structures with semi-rigid joints.

Key Words

damage identification; Euler-Bernoulli beam model; FRP strengthening; lattice shell structures; residual axial capacity; semi-rigid joints

Address

Shu-Hui Huang — 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 2) School of Civil Engineering, Southeast University, Nanjing 210096, China
Wen-Jie 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 2) School of Civil Engineering, Southeast University, Nanjing 210096, China
Ze Yang — School of Civil Engineering, Southeast University, Nanjing 210096, China
Ming-Liang Zhu — School of Civil Engineering, Southeast University, Nanjing 210096, China
Zhi-Wei Shan — 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 2) School of Civil Engineering, Southeast University, Nanjing 210096, China
Kun Liang — Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
Daniel Ting-Wee Looi — Civil Engineering, School of Engineering and Technology, Sunway University, Bandar Sunway, 47500 Selangor, Malaysia

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