Precast Reinforced Concrete Research Articles

Observational loss database of typological precast RC buildings damaged after the 2012 Emilia Earthquake

The Emilia Earthquake occurred in 2012 in a highly industrialized area, characterized by the presence of about one firm every 9 inhabitants. The industrial heart of the region hosts many important clusters, from the Motor Valley to Food, Wellbeing, Fashion and Health devices. The main activities are conducted in production districts with several different long-span buildings like storages, deposits, warehouses, factories and silos. Among these, those made of precast reinforced-concrete (RC) elements were heavily damaged by the seismic sequence, resulting in a huge amount of economic losses due to damage to structures, products and machineries, business interruption and casualties. In the aftermath of the earthquake, the Region defined the criteria for the request of funds for the reconstruction of the buildings, the restoration of the products, the reparation of the equipment, and the temporary relocation of the activities. Thus, a large number of documents was collected reporting a variety of information concerning the seismic damage, the structural properties of the buildings, and the economic costs.In this work, through a process of progressive selection and refinement of the data, a database of seismic economic losses of damaged precast RC buildings was created. The main principles for the creation of the repository and the categorization of the information are illustrated. Hence, the losses were statistically analysed to derive useful consequence functions based on the investigation of diversified trends of the repair costs at different damage levels. The outcomes presented in this study may be adopted to perform loss assessment evaluations to guide the decision-makers in establishing priorities of structural interventions to reduce the consequences of future earthquakes in industrial areas.

Optimal Design of Sustainable Reinforced Concrete Precast Hinged Frames

Sustainable development requires improvements in the use of natural resources. The main objective of the present study was to optimize the use of materials in the construction of reinforced concrete precast hinged frames. Proprietary software was developed in the Python programming language. This allowed the structure's calculation, verification and optimization through the application of metaheuristic techniques. The final cost is a direct representation of the use of materials. Thus, three algorithms were applied to solve the economic optimization of the frame. By applying simulated annealing, threshold accepting and old bachelor's acceptance algorithms, sustainable, non-traditional designs were achieved. These make optimal use of natural resources while maintaining a highly restricted final cost. In order to evaluate the environmental impact improvement, the carbon-dioxide-associated emissions were studied and compared with a reference cast-in-place reinforced concrete frame. The results showed designs with reduced upper slab and lateral wall depth and dense passive reinforcement. These were able to reduce up to 24% of the final cost of the structure as well as over 30% of the associated emissions.

Restoring Force Model of Precast Segmental Reinforced Concrete Piers after Seawater Freeze–Thaw Cycles

Precast segmental reinforced concrete (RC) piers have been widely used in the construction of offshore bridges to speed up construction. Offshore bridges in cold regions are inevitably affected by the seawater freeze–thaw cycles under the periodic movement of tides, which could reduce the mechanical property of RC piers. Based on the low cyclic loading test on 12 specimens with different seawater freeze–thaw cycles, axial compression ratio, diameters of longitudinal reinforcement, and stirrup spacing, the hysteresis characteristics of precast segmental RC piers were analyzed. The test results show that the peak load decreased by 11%, while the peak displacement increased by 40% after 125 seawater freeze–thaw cycles. The hysteresis curves became fuller and the residual displacement became smaller with the accumulation of freeze–thaw damage. In the same 125 freeze–thaw cycles, the peak load increased by 15% and 27% while increasing the axial compression ratio and the longitudinal reinforcement diameter. Combined with the regression analysis of the experimental results, the restoring force model of RC piers considering the seawater freeze–thaw damage and design parameters was established, and the calculation method of each characteristic point in the model was given. The deviation values of flexural capacity are not more than 6.5%, and the deviation values of peak displacement are not more than 12%. The restoring force model determined in this paper could provide a reference for seismic response analysis of offshore bridges in cold regions.

Seismic response of prestressed precast reinforced concrete beam-column joints assembled by steel sleeves

A novel prestressed precast reinforced concrete (RC) beam-column joint, composed of prestressed tendons, stiffened steel sleeves, and high-strength bolts, having improved self-centring ability and assembly efficiency is proposed in this paper. Four prestressed precast RC joints assembled by steel sleeves and one cast-in-place RC joint were tested under cyclic loading to investigate the seismic response of the proposed joint. The main parameters studied are the axial compression ratio of columns, stirrup ratio in the core area of the proposed joint and effective prestress of tendons. The energy dissipation capacity, bearing capacity, and self-centring ability of the prestressed precast RC beam-column joints assembled by steel sleeves are higher than those measured for the cast-in-place RC joint. For the prestressed precast RC joints assembled by steel sleeves, both yield and ultimate displacements increase with the increase of the axial compression ratio, stirrup ratio and effective prestress, but the ductility decreases with the increase of the axial compression ratio and effective prestress. The increasing of axial compression ratio can lead to an increase in the energy dissipation capacity, shear capacity and residual displacement. Finally, formulae to predict the shear capacity of prestressed precast RC joint assembled by steel sleeves are proposed, being in good agreement with the experimental results.

Seismic Pushover Analysis of Global Emulative Response of Precast Reinforced Concrete Frames with Dextra Groutec Couplers

The effects of Dextra Groutec couplers on the global performance of precast reinforced concrete frames are investigated by comparing the performance criteria of conventional RC structures to that of the said structures such that precast elements are connected end-to-end using these couplers. As couplers provide continuity of the reinforcement, precast elements that are connected using this mechanism can perform as a unit, and the entire structural system can be considered emulative as long as the structural performance is comparable to that of the conventionally designed cast-in-place. Dextra couplers inherently have lower strain compared to reinforcing rebar, affecting the global performance of a structure if placed within critical regions such as near the beam-column connection. The present study is conducted therefore to perform a comparative study to determine the effect of these couplers on the emulative behavior of the precast frames to the cast-in-place frames by considering the following factors: Coupler location, Dextra Groutec Coupler size and length, and the story height of the frame. Static pushover analysis of 30 models is carried out using the finite element software, Seismostruct. Pushover curves are compared based on the three criteria such as global ultimate displacement, displacement ductility, and energy dissipation. The results revealed that the Dextra Groutec Couplers reduce the capacity of the precast frame according to the three performance criteria. Hybrid configuration, where the bottom part is CIP and the upper part is precast connected by couplers is found to be the most viable option to obtain an emulative response. The longer and bigger Dextra Groutec coupler, S28 also manifested more inferior performance compared to S25. Lastly, the height of the structure is not a strong factor in the emulative response except for the hybrid and coupler placed at D distance away from the joint face configurations.

Structural Behavior of a Laterally Restrained Precast Reinforced Concrete Arch Deck Under Punching Shear Loading

In the construction of concrete bridges, the lighter dead load of decks can significantly reduce the number or size of substructure members, such as girders, piers and foundations. Although, the arch decks (ADs) ensure superior load carrying capacity and can have longer span length than flat decks (FDs), relatively minute number of studies was performed on longer span decks manufactured as arch shape to maximize the performance. In the previous study, a precast reinforced concrete (RC) AD with enhanced width of 2.5 m was developed. In this study, the behavior of precast RC AD under punching shear load was studied. Three real-scale AD specimens were tested and analyzed to understand its performance under punching shear loading. Different sizes of the ADs were manufactured to evaluate the punching shear capacity. The punching shear capacity and failure mode were obtained from the test, and the results were then compared to various design provisions. Finite Element Analyses (FEAs) were conducted to validate the experiment results and to verify the arching action of the AD with various thicknesses. The study results clearly verified that the AD had a higher or similar load-carrying capacity than the FD due to the arching action caused by the lateral restraint and arch shape, despite of thinner thickness of AD than FD. An analytical and prediction model for the punching shear behavior of ADs was developed and calibrated. The resulting models are described in a code-friendly formulation.

Progressive collapse fragility of substandard and earthquake-resistant precast RC buildings

Several natural and man-made disasters have highlighted that precast reinforced concrete (RC) buildings often have insufficient levels of structural robustness, which is the last line of defence under extreme events. Even though robustness studies were originated by the progressive collapse of the Ronan Point precast RC building in 1968, such a structural feature of disaster resilience has been partially investigated in case of precast RC buildings to date. In this study, a precast RC frame structure representative of low-rise commercial buildings is analysed under different column loss scenarios, which can produce the partial or total collapse of the structural system. Two building classes are considered, namely, buildings designed only to gravity loads and buildings designed for earthquake resistance. Structural robustness is probabilistically assessed through a fragility analysis procedure, using three-dimensional fibre-based finite element models with nonlinear links simulating connections, large-displacement incremental dynamic analysis, and multiple performance limit states for damage assessment. The output of the study is threefold: (i) a detailed assessment of the effects of column loss on precast RC frame buildings, quantifying the major role of structural detailing and beam-column connections; (ii) a fragility-informed evaluation of beneficial effects of seismic detailing on structural robustness, which can drive designers in retrofitting of existing precast RC buildings and decision-makers towards prioritization-related issues; and (iii) the generation of typological fragility curves for progressive collapse risk assessment in both single- and multi-hazard environments. Progressive collapse fragility curves can be convolved with more classical fragility models describing the failure of single components (under, e.g., flow-type landslide impact, vehicle collision or blast) and hazard, to assess systemic structural risk.

Retrofitting of a Precast Reinforced Concrete Industrial Building Using Friction Dampers Without Stopping Functionality

This paper presents a seismic retrofit of an industrial-type precast reinforced concrete building structure using friction dampers. This project consisted of retrofitting two precast reinforced concrete buildings, of which one of them will be presented here. Precast concrete is one of the most preferred methods of construction for industrial structures due to its low cost, fast construction and availability in rural areas. Unfortunately, most structures constructed before “Specification for Buildings to be Built in Seismic Zones(TBDY 2018)” are not sufficiently engineered and are expected to have poor performance when exposed to a major seismic event. Because stopping the production cost can be tolerated by the owners, a retrofitting technique that can be assembled during normal function of the industrial structures is required. As a result of this requirement, friction dampers are selected as the supplemental energy dissipation device. ASCE 41-17 [10] is employed for the damper design and performance evaluation of the building. Before the damper study, some instability and weak connection problems are solved by some traditional measures of strengthening. The most effective damper configuration and capacities are selected after an iterative trial-and-error linear study using the simplified methods developed by PROMER. Nonlinear push-over analysis are conducted after linear prestudies. Finally, a nonlinear time-history analyses is performed for confirmation of the results. , It is shown that the proposed retrofit scheme satisfies the desired performance goals for both DBE and MCE events. Overall, it is considered that proposed retrofit scheme with dampers provides the optimal solution for the stakeholders of the project from a performance, design, constructability, and economical point of view. Some application photos will be presented and methods are explained in detail in the paper. The friction damper behavior is based on the rotational friction hinge concept

Development of a Dataset from Shaking Table Tests of a Bridge System with Precast Reinforced Concrete Columns Equipped with Springs

This article describes the publicly available dataset of multiple shaking table tests on a restrained rocking and sliding bridge system exhibiting negative lateral stiffness. Given the scarcity of experimental campaigns on such systems, this dataset is valuable for the development and validation of analytical and numerical models, with 184 tests. This large body of data allows the models to be validated in a statistical sense. This work describes in detail the specimen and its construction, as well as all instrumentation used during the tests. It presents the organization of the shared data, and concludes with some examples of how the available data can be postprocessed for assessing the behavior of the system.

Research on performance degradation analysis method of offshore concrete piers in cold regions

Due to the influence of periodic tidal changes, the offshore reinforced concrete (RC) bridge piers in cold regions have been subjected to seawater freeze-thaw cycles (FTCs), which seriously affects the service performance of bridges. Based on this, the RC precast segment of the bridge pier under seawater FTCs was carried out, and the FTCs damage distribution was obtained by ultrasonic tomography technology. Considering the critical saturation theory, temperature distribution characteristics, pore crystallization theory and pore pressure model, the prediction method on the FTCs damage was established from micro-scale. Subsequently, the equivalent numerical simulation model of RC pier with FTCs was established from multi-scale. The test and calculation results show that the micro-calculation model can well simulate the pore accumulation and pore transformation, which can well describe the pore evolution behavior of concrete under FTCs. Moreover, the hysteretic curve obtained by the equivalent model is in good agreement with the test result. With the increasing FTCs, the peak load of the RC pier decreases gradually, which the FTCs damage seriously affects the mechanical properties of the RC pier, and there is an obvious FTCs damage limit in the RC piers.

Experimental and numerical investigation on collapse behavior of precast reinforced concrete beam-column sub-assemblages with cast-in-place ECC joints

In order to investigate the effects of engineering cementitious composite (ECC) used as post-cast materials and anchorage length of beam longitudinal rebars in the ECC cast-in-place joints on collapse behavior of precast reinforced concrete (PRC) structures, static pushdown collapse tests on scaled PRC beam-column (BC) sub-assemblages were carried out. Three BC sub-assemblage specimens having a double-span beam and a middle column joint were designed and fabricated with the same geometric dimensions, including one monolithic specimen BC0 and two PRC specimens BC1 and BC2. The specimen BC0 was cast in site with normal concrete, while the double-span beams of specimens BC1 and BC2 were first cast with normal concrete and then the middle column joint was post cast with ECC. The anchorage length of beam longitudinal rebars embedded into the middle joint was 29d, 20d, and 10d (d is the diameter of beam rebar) respectively for specimens BC0, BC1, and BC2, which could produce different splice length in the middle joint. On the basis of tests, refined finite element (FE) models were established and reasonably verified by a detailed comparison between numerical and experimental results. Based on the validated FE models, a parametric analysis was performed to study the effects of horizontal constraint stiffness, anchorage length, and bond strength between beam longitudinal rebars and ECC on collapse resistance of PRC sub-assemblages. The results showed that the application of ECC as the post cast material in the joint of PRC sub-assemblages could achieve similar collapse behavior to the monolithic counterpart and reduce the anchorage length of beam longitudinal rebars with a suggested lower limit of 20d. The bond strength between rebar and ECC in the joint had obvious influence on the collapse resistance and deformation capacity at large deformation stage.

Experimental Study on Seismic Performance of Precast Pretensioned Prestressed Concrete Beam-Column Interior Joints Using UHPC for Connection.

The traditional connections and reinforcement details of precast RC frames are complex and cause difficulty in construction. Ultra-high-performance concrete (UHPC) exhibits outstanding compressive strength and bond strength with rebars and strands; thus, the usage of UHPC in the joint core area will reduce the amount of transverse reinforcement and shorten the anchoring length of beam rebars as well as strands significantly. Moreover, the lap splice connections of precast columns can be placed in the UHPC joint zone and the construction process will be simplified. This paper presented a novel joint consisting of a precast pretensioned prestressed concrete beam, an ordinary precast reinforced concrete (RC) column, and a UHPC joint zone. To study the seismic performance of the proposed joints, six novel interior joints and one monolithic RC joint were tested under low-cyclic loads. Variables such as the axial force, the compressive strength of UHPC, the stirrup ratio were considered in the tests. The test results indicate that the proposed joints exhibit comparable seismic performance of the monolithic RC joint. An anchorage length of 40 times the strands-diameter and a lap splice length of 16 times the rebar-diameter are adequate for prestressed strands and precast column rebars, respectively. A minimum column depth is suggested as 13 times the diameter of the beam-top continuous rebars passing through the joint. In addition, a nine-time rebar diameter is sufficient for the anchorage of beam bottom rebars. The shear strength of UHPC in the joint core area is suggested as 0.8 times the square root of the UHPC compressive strength.

Experimental and numerical investigation on the seismic performance of masonry walls reinforced by PC panels

The use of precast reinforced concrete (PC) panels to strengthen existing old masonry structures was presented in this study. Quasi-static tests were done on one unreinforced masonry wall and three reinforced wall specimens with varied connection forms to study the seismic performance of the masonry walls reinforced by PC panels and verify the effectiveness of the applied connection forms. The hysteretic response of all reinforced masonry walls differed significantly when different connection forms were applied, according to experimental results. Based on the experimental results, the proposed reinforcement method using one-sided connected PC panels can effectively improve the seismic performance of existing masonry walls in terms of shear strength, stiffness, and energy dissipation capacity. Finally, the numerical simulation models for the specimens were established to further investigate the damage mechanisms, and the hysteresis curves and failure modes of specimens obtained from numerical analysis were in good agreement with the experimental results, indicating that the proposed analytical model can be practically used to predict the performance of masonry structures strengthened by the new reinforcement technique.

Issues Regarding the Appropriateness of Using Precast Reinforced Concrete Frame Structures Compared to Monolithic Reinforced Concrete Frame Structures, in Office Buildings and Residential Buildings

Abstract Given the current context at national and European level in terms of reducing skilled labour force in constructions, as well as the high level of density and traffic in large cities, there is an increasing emphasis on the possibility of shortening the duration of building the structural frames on site, reducing the number of workers or even reducing the level of noise pollution. Thus, the introduction of precast technologies in the case of office buildings and residential buildings, with multi-storey frame structure, is becoming an increasingly pressing and topical issue. The purpose of this paper is to enable structural engineers, architects and potential investors to consciously choose the type of optimal structure, taking into account a number of technical and economic aspects. In this sense, in order to highlight the main advantages and disadvantages of using multi-storey precast reinforced concrete frame structures, a comparative case study will be carried out between a precast frame structure and a monolithic frame structure, respectively.

Experimental and numerical investigation on seismic performance of semi-precast concrete sandwich shear wall

This study investigated the seismic performance of an innovative semi-precast concrete sandwich shear wall (SCSSW) system. The system consists of two precast reinforced concrete (RC) wythes, a core cast-in-place RC wythe, a core thermal insulation layer, the fiber reinforced polymer connectors and the steel trusses. A total of three RC shear wall specimens were fabricated and tested under in-plane cyclic load. They consists of one conventional cast-in-place RC shear wall, one structural wythe of SCSSW (i.e., the assemble of a precast and a cast-in-place RC wythe), and one typical SCSSW. The failure mode, hysteretic curve, ductility and energy dissipation of the three specimens were studied and compared. Furthermore, numerical simulation based on multi-layer shell element was conducted to reproduce the test, and parametric analysis was conducted to facilitate a better understanding on the SCSSW. It was concluded that the SCSSW presented a ductile failure behavior; the seismic performance of the SCSSW including hysteretic curves, skeleton curves, stiffness degradation and the energy dissipation was similar to that of the cast-in-place RC shear wall, while the ductility of the SCSSW was slightly lower; and the facade precast RC wythe contributed few effect on the seismic performance of the SCSSW.

Seismic assessment of existing precast RC industrial buildings in Portugal

Precast reinforced concrete (PRC) buildings are common on European industrial parks. In past earthquakes, namely in Italy and Turkey, this typology of buildings showed a poor performance, namely at structural level. One of the major concerns at structural level regards the connection between the beams and columns. Two types of beam-to-column connections are more common in this type of buildings: the pure friction and a mechanical one including steel dowels. The seismic performance of six existent Portuguese PRC buildings built with these two solutions are analyzed considering nonlinear static and dynamic analyses addressing both global (columns) and local (connections) response parameters. The seismic assessment in view of the regulation for existing buildings (Eurocode 8 –Part 3) showed that, overall, this typology of buildings, present an acceptable structural performance. Nonetheless, unsatisfactory performance was observed at the beam-to-column connection in one of the buildings built without steel dowels. In terms of non-structural performance, namely in terms of the cladding elements, a poor performance is foreseen, for regions of moderate to high seismic action, regardless of the period of construction of the building.

Experimental and numerical investigation on the performance of adhesive steel-dowels used in precast reinforced concrete elements

Precast reinforced concrete (PCRC) applications provide several structural, economic, and environmental benefits. Therefore, recently the PCRC elements have been widely used in construction implementation. However, the connection's behavior and its possible failure under different types of loads are considered essential challenges during the design of the PCRC elements. This study aimed to investigate the performance of the adhesive dowels connections and their shear capacity. The experimental phases focused on examining eighteen push-off concrete specimens and four reinforced concrete (RC) beams-column connections. While the numerical phase was conducted using the finite-element software package ANSYS to simulate concrete connections behavior. Push-off specimens consisted of two concrete blocks measured 250 mm in width. Blocks connected by steel dowel that crossed the shear plane. While beams measured 120 mm in width, 300 mm in depth, and 1400 mm in length. Beams connected to existing 300 mm square column with adhesive dowels. All specimens were loaded monotonically until failure through a constant loading rate. The experimental study aimed to evaluate the effects of the shear plane depth, dowels’ embedded length, dowels’ diameter, the edge distance, and dowels ratio The test results revealed that the shear plane conditions and area, as well as the adhesive dowels configurations, had a significant effect on the shear capacity of dowel specimen. Moreover, the finite element model provided a better understanding of the different modes of failure observed during experimental testing and the shear capacity of adhesive dowels.

An RBS-based replaceable precast concrete beam-column joint: Design approach and experimental investigation

In traditional reinforced concrete (RC) frame systems, severe damage usually occurs in the beam-column joint zone under strong earthquakes, which increases the post-earthquake repair difficulties in restoration speed and expenditure. In response to this problem, a new reduced beam section (RBS)-based steel beam-column joint for seismic-resistant precast concrete (PC) frames was proposed, to achieve the damage control for rapid replacement and restoration. The RBS-based beam-column joint (RBSJ) is installed in the beam end close to the column so that the plastic hinge will develop at the predetermined location. The design procedure of the replaceable RBSJ was developed, and the cyclic loading tests of two 1:2 scale specimens including a monolithic joint (MJ) specimen and a RBSJ specimen were carried out. Test results demonstrated that the proposed RBS-based joint exhibited expected failure mode and excellent hysteretic response, compared with the monolithic joint. Additionally, the damaged RBSJ specimen was subsequently replaced in situ for three times, and the quasi-static test was performed for each replaceable specimen. The test results demonstrated the replaced RBSJ specimens behaves the same behavior as the origin specimen, indicating the proposed joint was feasible in precast RC framed structures.

Cyclic behaviour of precast beam‐to‐column connections with low seismic detailing

AbstractBeam‐to‐column connections are a crucial element in industrial precast reinforced concrete (PRC) buildings. They are also the source of several damages reported after recent earthquakes. This typology of buildings is very common both in the Portuguese industrial park and throughout Europe. In order to have a better knowledge of the connection behaviour an extensive experimental work was done and it is here presented to characterize, under cyclic loading, the pure friction behaviour and friction and dowel beam–to–column behaviour. The research was focused on the parameters that might influence the seismic performance of the connections. These are the friction between elements, the absence or presence of dowels and their position on the column's corbel, and finally the different axial load level applied on the connections. The results presented in this study pointed to the importance of using neoprene pad between concrete faces, with the main objective of damage control. The use of mechanical connectors (dowels) was also highlighted as a source of increasing the strength of the beam–to–column connection in values greater than 50%.

A Semi-Active Control Technique through MR Fluid Dampers for Seismic Protection of Single-Story RC Precast Buildings.

The work proposes an innovative solution for the reduction of seismic effects on precast reinforced concrete (RC) structures. It is a semi-active control system based on the use of magnetorheological dampers. The special base restraint is remotely and automatically controlled according to a control algorithm, which modifies the dissipative capability of the structure as a function of an instantaneous dynamic response. The aim is that of reducing the base bending moment demand without a significant increase in the top displacement response. A procedure for the optimal calibration of the parameters involved in the control logic is also proposed. Non-linear modelling of a case-study structure has been performed in the OpenSees environment, also involving the specific detailing of a novel variable base restraint. Non-linear time history analyses against natural earthquakes allowed testing of the optimization procedure for the control algorithm parameters, finally the capability of the proposed technology to mitigate seismic risk of new or existing one-story precast RC structures is highlighted.