This article presents time-independent probabilistic seismic hazard maps for El Salvador in terms of the vertical component of motion regarding the peak ground acceleration and spectral ordinates for 0.2 and 1 s of 5
Intensity measure (IM) serves as a core variable in performance-based earthquake engineering (PBEE). However, for the simply-supported-bridge-vehicle coupled system (SSBVCS) subjected to cross-strike-slipfaulting (CSSF), the optimal selection of IMs remains challenging due to the complex multi-directional effects of faulting, the influence of fault-bridge spatial relationships, and the scarcity of recorded ground motions. To address this, this study proposes a modified IM selection framework for cloud analysis (CA), which enhances the accuracy of efficiency evaluation through normalization of IMs. Application of this framework demonstrates that under the coupled fling-step and forward directivity effects of CSSF, peak spectral displacement (SDmax) and peak spectral velocity (SVmax) exhibit superior performance for probabilistic seismic demand models. Meanwhile, IMs of the fault-parallel (FP) component perform consistently well in integrated assessments across multiple engineering demand parameters (EDPs). For specific engineering scenarios with fault-bridge crossing angles of 90° and 45°, SDmax, GM (geometric mean) and SDmax, FP are selected as the optimal system-level IMs for each case, respectively, offering balanced efficiency and sufficiency across six representative EDPs of the SSBVCS.
To improve the seismic resilience of precast concrete moment frames, a replaceable fuse connection at the splice location representing the beam inflection point under gravity load was proposed previously by the authors. This connection incorporates shear tabs at the beam top acting as both the rotational center and shear transfer components, along with two buckling-restrained braces (BRBs) at the beam bottom serving as the fuse. The shear tabs are vertical steel plates embedded across the splice section and into the adjacent beam segments, with shear studs welded on the embedded parts to facilitate force transfer. While prior tests have validated the damage-control concept, design criteria for the shear tabs to ensure reliable force transfer between beam segments under combined axial, shear, and bending actions are still lacking. In this study, calibrated finite element models (FEMs) of the proposed connection were constructed to clarify the force transfer mechanism of the shear tabs. Informed by this mechanism, design methods for the shear tabs were presented, incorporating both strength criteria to ensure effective force transmission and damage-control criteria to avoid premature fracture under cyclic loading. These methods were validated using FEMs with variations in the cross-sectional dimensions and height-to-thickness ratios of the shear tabs, as well as in the arrangements and diameters of shear studs welded on the embedded parts.
Scalar damage indices for retrofitted reinforced concrete frames are calibrated against one intervention family and record how much damage has occurred rather than which mechanism produced it, so they neither transfer between retrofit types nor warn when a brittle mode is about to govern. The Mechanism Evolution Index (MEI) addresses this gap for non-ductile RC frames retrofitted with bonded carbon fiber-reinforced polymer (CFRP) jackets or steel buckling-restrained braces, within the scope of regular planar systems under single-direction motion. Six independently measurable response constituents combine through one frozen weight set, anchored once at the joint-panel cracking and sliding thresholds of a three-specimen calibration series, into a bounded scalar on the unit interval and a ternary coordinate that separates ductility, shear, and connection demand. The set is fixed once and applied without re-tuning across retrofit type and intensity. The framework is demonstrated on a one-third-scale specimen series, a bare frame with three-ply CFRP and tube-in-tube brace retrofits, reproduced by one calibrated OpenSees model. The bare frame becomes connection-dominated and approaches the sliding threshold at the design intensity, the CFRP jacket suppresses joint engagement then collapses through the same band at the ultimate level, and the brace stays on the ductility axis throughout. Transferability is examined on six external cases outside the calibration, four bare and two retrofitted; the source-reported mechanism sits on the leading ternary axis in every labelled case. The classical scalars track damage severity but cannot name the mechanism, whereas the connection component supplies an indicative retrofit-screening level.
This study investigates the cyclic performance of exterior reinforced concrete (RC) beam–column joints in which the normal concrete within the joint core is partially replaced by a fiber-strengthened epoxy composite (SFREC), consisting of an epoxy binder, silica sand, cement–microsilica filler, and hooked-end steel fibers. The experimental program was conducted in two stages. First, SFREC mixtures were characterized through compressive, direct tensile, and flexural tests, and the mixture F30-EB15-SF1.0 was selected based on a multi-criteria performance ranking. Second, three half-scale exterior RC beam–column joint specimens were tested under quasi-static reversed cyclic loading: BCJ-REF, a reference joint without transverse reinforcement in the joint core; BCJ-TR, a normal-concrete joint incorporating conventional joint-core transverse reinforcement; and BCJ-SFREC, a joint incorporating the selected SFREC mixture as a partial joint-core replacement. The verified results showed that BCJ-SFREC achieved the highest peak load, Pmax=6.23 kN, corresponding to increases of 55.4
