Precast concrete construction has become a cornerstone of building industrialization because it offers rapid assembly, easier quality control, and a smaller environmental footprint than conventional cast-in-place methods. Yet the beam-column joints that tie these structures together remain a persistent engineering challenge. These regions experience some of the most complex stress states in an entire frame, transferring and distributing internal forces while holding the structure together during violent ground shaking. In traditional precast joints, columns are typically spliced with grouted sleeves or grouted lap splices, techniques that demand exceptional workmanship on site. Incomplete grouting is a common defect, and the story-by-story assembly process requires extensive temporary shoring that consumes space, prolongs construction, and accumulates installation errors.

To overcome these shortcomings, the research team led by Xiao-Ran Wang and He-Tao Hou of Shandong University developed what they call a latticed steel-concrete composite, or LSCC, beam-column joint. The design builds on multi-story precast column technology, in which columns spanning two or three stories are cast as a single unit in the factory and hoisted into place, leaving the joint regions open for wet connections. The new joint fills these open regions with a latticed steel column connector fabricated from chords, batten plates, through-diaphragms, and welded cross stiffeners. Structurally, the chords behave like the longitudinal reinforcement of a conventional column, while the batten plates act as stirrups. Before the joint concrete is poured, the chords provide a continuous load-transfer path across the open joint zone, and the cross stiffeners restrain local distortion of the central latticed segment, giving the column temporary stiffness, integrity, and stability during transport and erection.

The connection to the beams is equally deliberate. Each precast beam end carries an embedded H-section steel connector, with the beam’s longitudinal reinforcing bars welded to the outer flange surfaces. During assembly, the H-section web is bolted to a connecting plate on the latticed column while the flanges are welded to the through-diaphragms. By substituting a latticed configuration for the solid-web steel components used in many earlier composite joints, the design cuts steel consumption substantially. The researchers calculated that an equivalent joint built with a solid-web steel tube would require roughly 103.7 kilograms of steel, whereas their latticed specimens needed only 84.6 and 79.8 kilograms, savings of 18.4 and 23.0 percent respectively.

To test the concept, the team fabricated three full-scale exterior joint specimens: a monolithic cast-in-place reference specimen and two precast LSCC specimens differing only in the width of the batten plates. The columns measured 450 by 350 millimeters in cross-section and stood 3,040 millimeters tall, while the beams were 350 by 250 millimeters and 1,780 millimeters long. All specimens used C30 concrete, Q355B steel plates, and HRB400 reinforcing bars, with weld lengths deliberately exceeding code minimums to improve reliability under cyclic loading. Each specimen was subjected to a constant axial load of about 1,050 kilonewtons on the column, representing a realistic design axial load ratio drawn from an actual multi-story precast frame project, while two hydraulic actuators pushed and pulled the beam tips in a low-cycle reversed cyclic protocol following Chinese seismic testing standards.

The differences in behavior were striking. The cast-in-place specimen developed dense diagonal cracks in the joint core, concrete spalling at the beam-column interface, and a pinched, inverse S-shaped hysteretic response caused by joint shear failure and bond-slip of the reinforcement. The two LSCC specimens, by contrast, showed minimal cracking in the joint core and plump, spindle-shaped hysteresis loops with negligible strength degradation. Their damage concentrated in the beam span, roughly 300 to 800 millimeters from the column face, rather than at the joint itself. In quantitative terms, the composite joints achieved peak loads 45.1 and 43.1 percent higher than the monolithic reference, ultimate displacements 56.6 and 50.8 percent greater, and cumulative energy dissipation at their ultimate states 135.8 and 115.6 percent higher. At a beam-tip displacement of 70 millimeters, their equivalent viscous damping coefficients exceeded the cast-in-place specimen’s by more than 80 percent.

Strain measurements and curvature analysis revealed the mechanism behind this superior performance. The embedded H-section steel stiffens the beam end so effectively that it relocates the plastic hinge, the zone of controlled flexural yielding where a structure is designed to absorb earthquake energy, away from the vulnerable joint region toward the beam span. In the cast-in-place specimen, the near-joint segment dominated flexural deformation, contributing up to 89 percent of the total displacement at large amplitudes. In the composite joints, once displacement exceeded 30 millimeters, the outer beam segments took over, with one segment alone contributing 54 percent of the deformation in a representative case. This more uniform curvature distribution allows a larger volume of material to participate in energy dissipation, which is precisely what seismic designers strive to achieve.

The team also built high-fidelity finite element models in ABAQUS, using the concrete damaged plasticity model and a reinforcement hysteretic constitutive law that accounts for bond-slip effects. The simulations reproduced the observed failure modes and damage evolution with peak-load errors below 7.1 percent, validating the modeling approach. A parametric study then explored design trade-offs. Thinning the latticed connector from 10 to 8 millimeters, a 7.4 percent steel saving, barely affected capacity, but reducing it to 4 millimeters cut peak load by 13.8 percent. Lengthening the embedded H-section steel increased capacity steadily, adding 6.9 to 13.5 kilonewtons of peak load for every 75 millimeters of additional length. Upgrading reinforcement from HRB400 to HRB500 or HRB600 raised peak capacity by 12.7 and 24.9 percent respectively, though the higher-strength bars showed slightly faster post-peak strength degradation due to their narrower plastic deformation margin.

The authors caution that their experimental conclusions rest on a single specimen per configuration, without repeated tests, so the reported improvements apply primarily to the dimensions, materials, and loading conditions investigated. Still, the implications are considerable. The study demonstrates that rational detailing, such as narrowing the batten plates in the joint core, can trim steel consumption by more than 5 percent with almost no loss of structural performance, and that a latticed connector can simultaneously solve the temporary-stability problems of multi-story precast columns and deliver seismic behavior that surpasses monolithic construction. If subsequent testing confirms these trends across a wider range of parameters, latticed steel-concrete composite joints could become an attractive option for resilient, rapidly assembled buildings in seismic zones worldwide.

Subject of Research: Seismic performance of novel prefabricated latticed steel-concrete composite beam-column joints

Article Title: Seismic performance of novel prefabricated latticed steel-concrete composite beam-column joints

Article References: Wang, X.-R., Hou, H.-T., Xia, H.-J., Zhang, B., Wang, D.-Y., & Liu, S.-Q. (2026). Seismic performance of novel prefabricated latticed steel-concrete composite beam-column joints. Results in Engineering, 32, Article 113355. https://doi.org/10.1016/j.rineng.2026.113355

Image Credits: AI Generated

DOI: 10.1016/j.rineng.2026.113355

Keywords: prefabricated concrete, beam-column joints, seismic performance, latticed steel connector, cyclic loading test, plastic hinge relocation, energy dissipation, finite element analysis, precast construction, steel-concrete composite, ductility, earthquake engineering

Prefabricated reinforced concrete construction occupies a distinctive place in structural engineering. Unlike cast-in-place buildings, whose columns and beams are monolithically poured, precast structures are assembled from factory-produced elements joined on site. This makes them fast and economical to build, but it concentrates seismic vulnerability in the connections. In the classic Turkish precast industrial building, roof girders rest on column corbels, typically through dowel bars and elastomeric bearing pads, and the entire lateral load path depends on how well these joints hold together when the ground lurches. The 2023 Kahramanmaraş earthquake sequence, with its pulse-like near-fault motions and unusually high vertical accelerations, tested those joints as severely as any event in Turkish history.

The research team began with field investigations in the affected region, documenting damage patterns across prefabricated buildings exposed to the twin shocks. Their reconnaissance identified a recurring catalogue of construction deficiencies: inadequate dowel detailing at girder-corbel connections, missing elastomeric bearing pads, substandard grout applications, and insufficient confinement reinforcement in columns and joints. Each of these defects, individually modest in appearance, proved capable of triggering or accelerating structural failure. Where bearing pads were absent, girders pounded directly against concrete corbels, crushing the bearing surfaces and losing their ability to accommodate the relative displacements that near-fault shaking imposes. Where dowels were poorly anchored or under-reinforced, the connections that should have tied roof girders to columns simply gave way.

These observations align with a long history of lessons from Turkish earthquakes. Precast structures were damaged in the 1998 Ceyhan earthquake, the 1999 Kocaeli earthquake, the 2011 Van earthquake, and the 2020 Sivrice earthquake, and in each event the same weak points surfaced: connections, corbels, and the detailing that modern codes require but field practice does not always deliver. What distinguishes the new study is that it does not stop at cataloguing damage. It converts the field evidence into quantitative fragility models, the statistical machinery that engineers use to estimate the probability that a structure will exceed a given damage state at a given level of ground shaking intensity.

Fragility analysis works by subjecting numerical models of a structure to suites of ground motion records and tracking how often a governing limit state, such as the onset of significant connection damage or loss of lateral load capacity, is exceeded as shaking intensity increases. The team built detailed nonlinear models of representative reinforced concrete prefabricated buildings and ran them through ground motions representative of the Kahramanmaraş sequence, including records with the velocity pulses and strong vertical components characteristic of near-fault sites. The resulting fragility curves provide a probabilistic portrait of vulnerability, allowing engineers to compare design variants on a common, defensible footing rather than relying on anecdote alone.

The single most striking quantitative finding concerns the roof girder-to-corbel connection. When the dowels connecting girders to columns were bolted, the seismic resilience of the structure improved dramatically: the median ground motion intensity at which the governing limit state was exceeded nearly doubled compared with structures relying on unbolted dowel connections. In practical terms, a building with bolted dowel connections could withstand roughly twice the shaking intensity before reaching its critical damage threshold. That is not an incremental improvement; it is the difference between a structure that survives a near-fault event and one that does not, achieved through a connection detail that costs comparatively little to implement.

The study also examined the role of infill walls, the masonry or precast panels that fill the bays between columns. In general, infill walls improved seismic resistance, stiffening the frames and sharing lateral load that would otherwise concentrate entirely on the columns. But the analysis revealed a crucial caveat: the benefit depended heavily on the integrity of the connections between the walls and the surrounding frame. Where those connections were robust, the walls acted as effective seismic fuses and load-sharing elements. Where the connections were poor, the walls detached early, their contribution vanished, and in some scenarios the falling panels introduced additional hazards. The lesson is that infill walls are not a passive benefit that can be assumed; they are only as good as the detailing that ties them into the structural system.

Near-fault effects emerged as a decisive amplifier of all these vulnerabilities. Earthquakes that rupture directly beneath or very close to a site produce ground motions with forward directivity, meaning a long-period velocity pulse arrives with much of the fault’s slip concentrated in a single large cycle of motion. The Kahramanmaraş events, including documented episodes of supershear rupture, delivered exactly this kind of pulse-like loading, along with vertical accelerations strong enough to degrade the friction and bearing capacity of simply supported precast elements. For connections already weakened by missing pads or deficient dowels, the combination of horizontal pulses and vertical acceleration was punishing. The study’s numerical results make clear that fragility assessments for precast buildings in near-fault zones must explicitly account for these motion characteristics rather than relying on generic record sets.

From these findings the authors draw a clear retrofitting agenda for the existing stock of reinforced concrete prefabricated structures. Priority measures include upgrading connection details, particularly bolting dowel connections at girder-corbel joints; adding elastomeric bearing pads where they are missing; and installing properly designed precast infill walls with reliable connections. Beyond the physical interventions, the study emphasizes the need for clear design guidelines and rigorous field assessment protocols so that existing buildings, especially in regions exposed to near-fault seismicity, can be systematically evaluated and reinforced before the next earthquake rather than after. The authors note that implementing these strategies would substantially enhance the seismic resilience of the precast building stock, reducing potential future human and economic losses.

The broader significance of the work extends beyond Türkiye. Precast industrial construction is common across seismic regions worldwide, from the Mediterranean to the Americas, and the failure modes documented after Kahramanmaraş echo those observed after the 2012 Emilia earthquakes in Italy, the 1994 Northridge earthquake in California, and the 1995 Kobe earthquake in Japan. The Turkish study adds a quantitative dimension to that international record, demonstrating with fragility curves just how much performance hinges on a handful of connection details. For engineers, the message is disarmingly simple: in prefabricated construction, the earthquake finds the joints. Bolting a dowel, seating a bearing pad, or grouting a connection properly may look like minor line items in a construction budget, but the difference they make, roughly a doubling of the shaking a building can survive, is the kind of margin on which lives and livelihoods depend when the fault finally slips.

Subject of Research: Seismic fragility and construction deficiencies of reinforced concrete prefabricated buildings in the 2023 Kahramanmaraş earthquakes

Article Title: Seismic performance assessment of reinforced concrete prefabricated structures during the 2023 Kahramanmaraş earthquakes: fragility analysis and construction deficiency evaluation

Article References: Seismic performance assessment of reinforced concrete prefabricated structures during the 2023 Kahramanmaraş earthquakes: fragility analysis and construction deficiency evaluation. (n.d.). https://doi.org/10.1007/s10518-026-02712-5

Image Credits: AI Generated

DOI: 10.1007/s10518-026-02712-5

Keywords: prefabricated concrete, Kahramanmaraş earthquakes, fragility analysis, seismic performance, dowel connections, corbel connection, elastomeric bearing pads, infill walls, near-fault ground motion, retrofitting, East Anatolian Fault, Bulletin of Earthquake Engineering