Precast Industrial Buildings Research Articles

Numerical Investigations of the Seismic Response of Precast Buildings with Beam-to-Column Connections with Steel Dowels

This study was developed within a research project concerning the seismic performance assessment of new or existing precast structures and reports some relevant results of numerical analyses performed on precast industrial buildings subjected to earthquake excitation. Analytical models based on results of experimental tests carried out within the research project were developed to reproduce the behaviour of beam-to-column connections with steel dowels. The models were extended to consider the effects of different parameters and correlated well with experimental results. The influence of numerical modelling of beam-to-column connections was investigated analyzing the seismic performance of a reference precast industrial building and comparisons with models with simple pinned beam-to-column connections were performed. Results of the numerical investigations showed that the plastic demand on columns decreased due to the energy dissipation contribution of beam-to-column connections, especially for medium-high seismic intensity levels. The building was able to withstand stronger seismic excitations, beyond the design earthquake, dissipating significant amount of energy through inelastic behaviour.

Neoprene–concrete friction relationships for seismic assessment of existing precast buildings

In Italy many precast industrial buildings built between 1950s and 1970s present beam–column connections with strength coming from neoprene–concrete friction. Numerical studies recently performed by the authors confirm that, in order to determine the seismic vulnerability of such structures, a reliable value of the neoprene–concrete friction coefficient has to be known. Technical bibliography provides many and different values for this coefficient; consequently, in order to define reliable values, a specific experimental campaign is carried out. Three types of experimental tests are performed: tests on neoprene hardness, tilting tests and pulling tests; in the last case, the specimen is also axially loaded.Tilting tests provide a value of the mean friction coefficient equal to about 0.5, with very low C.O.V.. Pulling tests underline a friction strength dependence on axial load and, in particular, a decrease in the friction coefficient as the axial load increases; a relationship for compressive stress–neoprene–concrete friction coefficient is proposed.

An innovative passive control technique for industrial precast frames

A feasibility study is presented on the extension to reinforced concrete (RC) precast industrial buildings of a passive control technique aiming to provide additional damping to the structure and previously proposed for RC and steel framed structures. This technique, based on the insertion of friction devices in the region of beam-to-column connections, is particularly advantageous due to the reduced dimension and low cost of the devices adopted. In the case of precast buildings, it offers the additional advantage of providing ductility to the hinged connections. In this work a general criterion for the device calibration is proposed; the modeling strategy for the device within a well-known simulation platform is presented. A prototype building is designed for a medium-to-high seismic risk and the device is fine-tuned for this particular building. The device efficiency in modifying favorably the structural behavior is analyzed by comparing the seismic response of the bare and redesigned frame to twelve accelerograms having a PGA equal to the design value. A non-critical shear increase in the zones where the device is inserted is found, largely counteracted by the reduction in extreme values for top displacement, bending moment at the column base and amount of energy dissipated in the hysteresis of materials.

Fragility based damage assesment in existing precast industrial buildings: A case study for Turkey

In Turkey, majority of industrial facilities are composed of precast buildings. However, precast buildings have suffered extensive damage during Kocaeli and Duzce (1999) and Adana-Ceyhan (1998) earthquakes. Therefore, in this study, fragilities of existing building stock and damage probabilities of precast buildings were studied. For this purpose, building inventories were prepared and variation of structural parameters was determined by investigating the design project of 65 precast buildings constructed in Denizli, Turkey. Twelve analysis models which reflect the stiffness, strength and ductility properties of building inventory were constructed. After the definition of strain based displacement limits and corresponding damage states for buildings, displacement demands were calculated by using non linear time history analysis. During the analyses 360 strong ground motion records were used. Exceedence ratios of concerned damage limits was calculated by checking the displacement demands and then PGV based fragility curves were constructed. Efficiency of strength, stiffness and ductility properties of existing precast buildings were investigated by comparing the fragility curves. The results have shown that the most effective parameters that govern the damage probabilities of precast buildings are stiffness and ductility. It was also stated that the results of fragility analysis and damage and failure observations performed after Kocaeli and Duzce Earthquakes are compatible.

Seismic collapse risk of precast industrial buildings with strong connections

AbstractA systematic seismic risk study has been performed on some typical precast industrial buildings that consists of assemblages of cantilever columns with high shear‐span ratios connected to an essentially rigid roof system with strong pinned connections. These buildings were designed according to the requirements of Eurocode 8. The numerical models and procedures were modified in order to address the particular characteristics of the analyzed system. They were also verified by pseudo‐dynamic and cyclic tests of full‐scale large buildings. The intensity measure (IM)‐based solution strategy described in the PEER methodology was used to estimate the seismic collapse risk in terms of peak ground acceleration capacity and the probability of exceeding the global collapse limit state. The effect of the uncertainty in the model parameters on the dispersion of collapse capacity was investigated in depth. Reasonable seismic safety (as proposed by the Joint Committee on Structural Safety) was demonstrated for all the regular single‐storey precast industrial buildings addressed in this study. However, if the flexural strength required by EC8 was exactly matched, and the additional strength, which results from minimum longitudinal reinforcement, was disregarded as well as large dispersion in records was considered, the seismic risk might in some cases exceed the acceptable limits. Copyright © 2009 John Wiley & Sons, Ltd.

Seismic assessment of existing precast industrial buildings using static and dynamic nonlinear analyses

Protection of existing constructions against natural hazards and in particular earthquakes is a relevant problem nowadays, since enlargement of seismic zones occurred in many European countries. As a consequence, a large number of constructions built without specific seismic provisions is characterized by relevant levels of structural risk. Quantitative evaluations of such risk is certainly of interest also for industrial buildings, that in many very urbanized areas are frequently subjected to extended and expensive interventions and changes of functional destinations. In this framework, a research study on industrial existing precast structures built in Italy between the 1950s and the 1970s appeared to be significant. Therefore, a large effort has been devoted to identify structural types, details and materials commonly adopted during the reference period. Then, attention has been paid to seismic vulnerability issues derived from nonlinear and dynamic analyses. Specific reference is made to elastic analyses under design forces with an evaluation of the relevance of the second order effects, to nonlinear static analyses by N2 method, also taking into account the vertical seismic component effects and to nonlinear dynamic analyses forcing the structure by all the three components of the earthquake. The presented research study shows that existing industrial precast buildings can be affected by severe damages under medium intensity seismic forces because of beam–column connection failure.

Cyclic response of slender RC columns typical of precast industrial buildings

The cyclic behaviour of slender cantilever columns in full-scale models of precast industrial buildings, designed by Eurocode 8, was studied experimentally and analytically. The shear span ratio of the columns was 12.5, which is more than allowed by Eurocode 8 for columns in frame structures (10). High deformability and a large deformation capacity (8%~drift) of the columns was observed. A lumped plasticity model was used in the analysis. In the paper the observed behaviour of the models has been compared with the predicted behaviour obtained by several empirically based models and procedures. It was observed that these models, which were developed for much lower shear span ratios (2–6), were not applicable for the analyzed very slender columns without appropriate additional considerations and modifications. In the case of such columns the yield drift is dominated by the flexural mode (it is practically proportional to the height of the column) and the ultimate drift under cyclic loading conditions is only slightly dependent on the shear span (indicating that the ratio of the equivalent length of the plastic hinge to the height of the column decreases with the increasing shear span). An appropriately modified lumped plasticity model incorporating in-cycle and repeated-cycle strength deterioration was chosen for future use in performance-based design and seismic risk studies.