M. J. Ameli

Seismic column-to-footing connections using grouted splice sleeves

Mechanical couplers have been used in connections between prefabricated reinforced concrete elements. Grouted splice sleeves offer good construction tolerance and a bond related load transfer mechanism between the connecting members. The present study investigates the seismic performance of grouted splice sleeve connections with the connectors placed in the column or footing of bridge subassemblies, and intentional debonding of the footing dowel bars. Quasi static cyclic loads were used to test three half scale precast column to footing specimens and one cast in place control specimen. The precast concrete specimens incorporated grouted splice sleeve connectors in which two bars were grouted at both ends. Experimental results show that the precast subassemblies had a lower displacement ductility capacity than the control specimen. Improved seismic response was observed when the splice sleeve connectors were located inside the footing rather than the column end. An intentional debonded reinforcing bar zone was used to further improve the displacement ductility capacity of the bridge subassembly.

Seismic Analysis of Precast Concrete Bridge Columns Connected with Grouted Splice Sleeve Connectors

AbstractReinforcing bar couplers are used in prefabricated bridge elements and bridge systems for accelerated bridge construction. Grouted splice sleeve connectors are used in bridge substructures because of the enhanced construction tolerances they offer. This paper presents a simplified modeling strategy for seismic assessment of precast bridge columns connected to precast footings using grouted splice sleeve connectors. A computational model was developed and validated using three half-scale bridge subassemblies tested to failure. Cyclic quasi-static loading was applied to two precast subassemblies and one cast-in-place specimen. The connectors were located in the footing, for the first precast alternative, and in the column end for the second precast alternative along with debonding of reinforcing bars in the footing. Force-based beam-column elements with fiber sections were used to construct the computational model based on plastic hinge weighted integration; the model included low-cycle fatigue and ...

Seismic Repair of Severely Damaged Precast Reinforced Concrete Bridge Columns Connected with Grouted Splice Sleeves

A repair technique for severely damaged precast reinforced concrete (RC) bridge columns with grouted splice sleeve (GSS) connections has been developed that uses a carbon fiber-reinforced polymer (CFRP) shell and epoxy-anchored headed bars to relocate the column plastic hinge. Four original specimens were built using an accelerated bridge construction (ABC) technique with two different GSS systems and were tested to failure using cyclic quasi-static loads. One GSS system was used to connect an RC bridge pier cap to a column and the second GSS system was used to connect an RC footing to a column. Failure of the four original specimens occurred at drift ratios between 5.6 and 8.0% with longitudinal bar fracture or pullout from the GSS connections. The repair method successfully relocated the plastic hinge to the original column section adjacent to the repair and was capable of restoring the diminished load and displacement capacity. The method is a viable and cost-effective technique for rapid seismic repair of severely damaged precast bridge assemblies.

Seismic performance of reinforced concrete building exterior joints with substandard details

Abstract Beam-column joints are important components of the seismic-force-resisting system in reinforced concrete (RC) frame buildings. A majority of older buildings have serious structural deficiencies and are substandard according to current seismic design criteria. Failure of beam-column joints with substandard details has caused building collapse during strong earthquakes. This paper evaluates the seismic performance of exterior beam-column joints with three different details of beam reinforcement; no transverse reinforcement was used in the beam-column joints. A total of six RC exterior joints with substandard details were tested under quasi-static cyclic loads and their performance was examined in terms of plastic rotation, joint shear strength and strain, and residual strength. Two levels of column axial compression were investigated and the influence of the axial load level on the performance of the joints is evaluated; in addition, the bond-slip behavior of the bottom beam bars is discussed. Joint shear failure and bond-slip failure were observed. The joint shear strength of the tested subassemblies exceeded the performance criteria stated in ASCE 41 for all test units with joint shear failure; however, joint shear strength was found to be lower than the requirements for Type 2 joints per ACI 352.

REPAIR OF DAMAGED PRECAST RC BRIDGE COLUMNS WITH GROUTED SPLICE SLEEVE CONNECTIONS USING CFRP SHELLS AND PLASTIC HINGE RELOCATION

A repair technique for damaged precast reinforced concrete (RC) bridge columns with grouted splice sleeve (GSS) connections has been developed that utilizes prefabricated carbon fiberreinforced polymer (CFRP) shells and epoxy anchored headed mild steel bars to relocate the column plastic hinge. Undamaged columns with two different GSS systems were tested to failure using cyclic quasi-static loads. One GSS system was used to connect an RC bridge pier cap to a column. The second GSS system was used to connect an RC footing to a column. Failure of the two original specimens occurred at drift ratios between 6% and 7% with longitudinal bars fracturing in the column plastic hinge region. The column plastic hinge region was then repaired by increasing the column cross section from a 21 in. octagonal section to a 30 in. diameter circular section with an 18 in. length. The repair was constructed using prefabricated CFRP shells. Headed mild steel bars were epoxy anchored into the pier cap and footing inside the CFRP shells. Nonshrink concrete was used to fill the void between the original columns and CFRP shells. Compared to the undamaged assemblies, the repaired specimens failed at the same drift ratios and greater ultimate load values. The plastic hinge was successfully relocated to the original column section adjacent to the repair and the failure mode was bar fracture in the relocated plastic hinge region. The method is a viable technique for seismic repair or seismic retrofit of precast GSS assemblies in column to footing or column to pier cap connections.