Seismic Behavior of Precast Buildings With Dissipative Connections

2021 ◽  
Vol 7 ◽  
Author(s):  
Lorenzo De Stefani ◽  
Roberto Scotta
Keyword(s):  
Sensitivity Analyses ◽  
Plastic Behavior ◽  
Seismic Action ◽  
Axial Forces ◽  
Precast Buildings ◽  
Non Linear ◽  
Frame System ◽  
Cladding Panels ◽  
Recent Earthquakes ◽  
Precast Structures

Recent earthquakes in southern Europe highlighted that the connections of cladding panels to R.C. frames in precast buildings had a major role in the structural collapse. For this reason, there is an urgent need for a review of the design methods for these connections as well as for an improvement in the manufacturing technology. This article aimed to assess the efficiency of dissipative panel-to-structure and roof connections in R.C. precast buildings. A parametric study consisting of linear and non-linear analyses on one case-study building is performed. Different sensitivity analyses are performed varying their mechanical properties (i.e., stiffness, strength, and ductility) to analyze the behavior of the CP/frame connections. The study focuses on dissipative connections with an elastic–plastic behavior, placed between cladding panels (CPs) and frames in precast buildings with stacked horizontal cladding panels. The introduction of dissipative CP/frame connections implies the inclusion of panels in the global seismic resisting system. The “panels + frame” system highlights a high stiffness until the yield strength of the CP/frame connections is reached. The results, obtained from non-linear dynamic analyses (NLDAs), clearly show how the proposed connection improves the structural seismic performance. By contrast, this is no longer true for R.C. precast structures with flexible diaphragms, especially for intermediate columns, far from panels aligned to seismic action. In this case, significant and unexpected axial forces arise on out-of-plane connections between panels and columns. The integration of an efficient diaphragm is essential to prevent these critical issues both on intermediate columns and CP/column connections; it enables the dissipative capacity of the “panels + frame” system, and it significantly limits the forces and displacements of intermediate alignments. Unfortunately, the achievement of a rigid diaphragm is not always feasible in precast buildings. A possible alternative to activate dissipative capacities of the roof diaphragm with limited in-plane stiffness is the use of dissipative connections linking roof beams and main beams. The solutions described in this article can be applied both in the design of new buildings and for the seismic upgrading of existing ones with easy-to-install and low-impact applications.

scholarly journals Out-of-plane capacity of cladding panel-to-structure connections in one-story R/C precast structures

2020 ◽  
Vol 18 (15) ◽  
pp. 6849-6882
Author(s):  
Giovanni Menichini ◽  
Emanuele Del Monte ◽  
Maurizio Orlando ◽  
Andrea Vignoli
Keyword(s):  
Experimental Tests ◽  
Structural Safety ◽  
Industrial Building ◽  
Seismic Load ◽  
Materials Testing ◽  
Main Structure ◽  
Precast Buildings ◽  
Out Of Plane ◽  
Cladding Panels ◽  
Precast Structures

Abstract The interaction between cladding panels and the main structure is a crucial point to assess the seismic response, and above all the structural safety, of RC precast industrial building. In the past, connections were often designed to allow construction tolerances and to accommodate both thermal and wind-induced displacements. The lack of specific details to allow relative in-plane displacements between cladding panels and the main structure often led to the participation of cladding panels in the structure seismic-resistant system with consequent connection failures. In the last decades, a lot of experimental tests were performed to investigate the in-plane performance of panel connections, and some design recommendations have been developed accordingly. In the out-of-plane direction, the connections were often considered to be infinitely rigid and not to suffer any damage by the seismic load. This work deals with the out-of-plane response of panel-to-structure connections for vertical panels typical of industrial and commercial precast buildings. Both standard hammer-head strap and new devices, called SismoSafe, were investigated. Tests were performed in the Structures and Materials Testing Laboratory of the Department of Civil and Environmental Engineering of Florence, where a specific setup was designed to perform cyclic and monotonic tests on the connection devices. Standard connections showed a rather limited resistance, while the innovative connections exhibited a high out-of-plane resistance. Numerical analyses were also performed on a case study building to evaluate the distribution of the out-of-plane demand on the connections.

Friction dissipative devices for cladding panels in precast buildings

2011 ◽  
Vol 15 (9) ◽  
pp. 1319-1338
Author(s):  
Liberato Ferrara ◽  
Roberto Felicetti ◽  
Giandomenico Toniolo ◽  
Carla Zenti
Keyword(s):  
Precast Buildings ◽  
Cladding Panels

scholarly journals Seismic Behavior of Mid-Rise Precast Reinforced Concrete Building with Effect of Joints and Supports

2019 ◽  
Vol 8 (4) ◽  
pp. 3633-3637
Keyword(s):  
Reinforced Concrete ◽  
Response Spectrum ◽  
Precast Concrete ◽  
Mode Shapes ◽  
Base Shear ◽  
Reinforced Concrete Building ◽  
Axial Forces ◽  
Building Models ◽  
Precast Buildings ◽  
Concrete Building

Precast concrete structures are widely used in construction. It consists of prefabricated elements casted in industry and connected to each other to form a homogeneous structure. Connections function is to transfer moments and axial forces. Many engineers assume precast connection as pinned, but in reality, they are semi-rigid connections that transfer forces to other members. Lack of design and detailing of connection leads to improper behaviour of the structure, which then leads to the collapse of the building. Past earthquake studies show that many precast buildings performed poorly, and the main reasons were connections. This paper mainly focuses on understanding the seismic behaviour of mid-rise i.e seven-storey precast reinforced concrete buildings with various beam-column joints i.e rigid, semi-rigid, pinned and column-base supports i.e, fixed and hinged supports. Building is modelled and analyzed using ETABS v17 software. Rotational stiffness of precast billet connection is adopted for modelling of semi-rigid beam-column connections. Response spectrum and modal analysis are carried out. Results of displacements, storey drift, storey shear, storey stiffness, base shear, time periods and first mode shapes of models are discussed. It is observed, precast reinforced concrete building models with semi rigid connection performs better than building models with pinned connections and building models with fixed supports reduces the structural response to a great extent.

Reducing Seismic out of Plane Vulnerability of Masonry Church Façades through Optimization of Capacity Spectrum by Tie Rods

2019 ◽  
Vol 817 ◽  
pp. 325-333
Author(s):  
Simonetta Baraccani ◽  
Giorgio Dan ◽  
Angelo Di Tommaso ◽  
Tomaso Trombetti
Keyword(s):  
Masonry Walls ◽  
Collapse Mechanisms ◽  
Capacity Spectrum ◽  
Construction Techniques ◽  
Non Linear ◽  
Out Of Plane ◽  
Recent Earthquakes ◽  
Discrete Element Methods ◽  
Tie Rods ◽  
The Church

The analyses of the structural damages detected on the Italian churches after the recent earthquakes (Emilia 2012, Umbria-Marche 2016) highlighted the high vulnerability to the overturning of the façades. The façades collapse mechanisms are strongly dependent on the connection details between orthogonal masonry walls, the windows, the construction techniques and the possible restraining horizontal elements, such as tie-beams, bi-lateral connected roof, etc. Several studies focus on the evaluation of vulnerability of the church façades using different approaches, from global analyses (FEM and /or Discrete Element Methods) of the entire building, to local analyses (linear and non-linear kinematic approaches). The aims of the present paper is to use the method based on capacity spectra to evaluate the vulnerability of the church facades and the optimization of specific devices as tie-rods to improve their seismic behavior. The non-linear approach is now accepted by several standards regarding the evaluation of risks of collapse mechanisms for masonry walls of the facades. Appropriate devices have been considered in order to calibrate the capacity curve and to optimize the interventions. The out of plane rotation of blocks can be modified with various elasto-perfect-plastic tendons with appropriate retentions (while composite materials could be used to preserve integrity of blocks). The tendons can be allocated in proper location and the length of each calibrated to best determine their stiffness. This procedure have been here applied to the study of the façade of Aula Magna S. Lucia of the Bologna University, considering also the problem of the interaction with the structure of the roof.

Seismic response of short restrainers used to protect cladding panels in RC precast buildings

2016 ◽  
Vol 24 (4) ◽  
pp. 645-658 ◽  
Author(s):  
Blaz Zoubek ◽  
Matej Fischinger ◽  
Tatjana Isakovic
Keyword(s):  
Analytical Formula ◽  
Seismic Protection ◽  
System A ◽  
Impact Forces ◽  
History Analysis ◽  
Precast Buildings ◽  
Cladding Panels ◽  
Response History Analysis ◽  
Accurate Procedure ◽  
The Impact

In the presented study, a second-line back-up system for the seismic protection of cladding panels in RC precast buildings is first presented. The system consists of special anchoring elements and a rope restrainer. The latter is activated only in the case when the existing connections between the primary structure and the panel fail, resulting in the occurrence of relatively large impact forces in the restrainer and in the anchoring elements. In order to adequately design the constitutive parts of the system, a simple yet sufficiently accurate procedure for the estimation of the impact forces is needed. A relatively easy-to-use formula was therefore proposed for this purpose. Next, an extensive parametric study, using response history analysis (RHA), was performed and the influence of several parameters affecting the impact forces in the restrainers was studied. The results obtained in the study were used to evaluate the proposed analytical formula. Considering the simplicity of the proposed formula, its accuracy was good. It can therefore be applied to the design of short restrainers which could be used in reinforced concrete (RC) precast buildings for the protection of cladding panels against the effects of earthquakes.

scholarly journals The Emilia Earthquake: Seismic Performance of Precast Reinforced Concrete Buildings

2014 ◽  
Vol 30 (2) ◽  
pp. 891-912 ◽  
Author(s):  
Gennaro Magliulo ◽  
Marianna Ercolino ◽  
Crescenzo Petrone ◽  
Orsola Coppola ◽  
Gaetano Manfredi
Keyword(s):  
Seismic Performance ◽  
Seismic Event ◽  
Seismic Vulnerability ◽  
Northern Italy ◽  
Epicentral Zone ◽  
Emilia Earthquake ◽  
Cladding Panels ◽  
Precast Structures ◽  
Epicentral Region ◽  
Extensive Damage

On 20 and 29 May 2012, two earthquakes of MW5.9 and MW5.8 occurred in the Emilia region of northern Italy, one of the most developed industrial centers in the country. A complete photographic report collected in the epicentral zone shows the seismic vulnerability of precast structures, the damage to which is mainly caused by connection systems. Indeed, the main recorded damage is either the loss of support of structural horizontal elements, due to the failure of friction beam-to-column and roof-to-beam connections, or the collapse of the cladding panels, due to the failure of the panel-to-structure connections. The damage can be explained by the intensity of the recorded seismic event and by the exclusion of the epicentral region from the seismic areas recognized by the Italian building code up to 2003. Simple considerations related to the recorded acceleration spectra allow motivating the extensive damage due to the loss of support.

scholarly journals Seismic actions induced by cladding panels on precast concrete frame structures

2018 ◽  
Vol 6 (3) ◽  
pp. 1-6
Author(s):  
Bruno Dal Lago ◽  
Francesco Foti ◽  
Luca Martinelli
Keyword(s):  
Precast Concrete ◽  
Rigid Bodies ◽  
Frame Structure ◽  
Eurocode 8 ◽  
Seismic Action ◽  
Concrete Frame ◽  
Out Of Plane ◽  
Connection System ◽  
Cladding Panels ◽  
Mechanical Devices

The strong earthquakes occurred in Southern Europe in the last decade pointed out a poor seismic performance of the connection system of the cladding of precast industrial structures. The cladding of these buildings usually consists of sandwich concrete panels of remarkable mass, connected to the frame structure with mechanical devices. The estimation of the out-of-plane seismic action on these connections is a key step for their correct proportioning. However, the formulation currently provided in the Eurocode 8 for the estimation of the seismic action on non-structural elements was calibrated with different objectives. Furthermore, given there is no in-plane structure-panel interaction, a quote of the panel mass is lumped in correspondence of their connection for a correct proportioning of the frame structure. The designers need to make assumptions on both aspects that often bring to remarkably different solutions. The paper presents a consistent dynamic formulation of the problem of the vibration of rigid bodies connected with cantilever columns. The solution brings to closed-form equations to evaluate the exact out-of-plane action on the connections and the correct amount of panel mass to be lumped.

scholarly journals Seismic Retrofitting Solutions for Precast RC Industrial Buildings Struck by the 2012 Earthquakes in Northern Italy

2021 ◽  
Vol 7 ◽  
Author(s):  
Fabio Minghini ◽  
Nerio Tullini
Keyword(s):  
Fragility Curves ◽  
Seismic Retrofitting ◽  
Rc Structures ◽  
Existing Structures ◽  
The North ◽  
Industrial Buildings ◽  
Precast Buildings ◽  
Damage Data ◽  
Emilia Romagna Region ◽  
Cladding Panels

In 2012, the North of Italy was hit by a seismic sequence characterized by two main events occurred on May 20 and 29 with MW = 6.1 and 6.0, respectively. Those earthquakes were particularly severe toward precast Reinforced Concrete (RC) structures not designed for seismic resistance. In the past years, the authors implemented a database collecting damage data and typological information on the industrial buildings struck by the Emilia earthquakes. That database was used to develop empirical fragility curves, which highlighted the considerable vulnerability of precast buildings conceived in accordance with pre-seismic code provisions. More recently, the interventions of seismic retrofitting on the same buildings, funded by the Emilia-Romagna region and designed by engineers which were directly hired by the companies, were examined in detail and critically revisited. A selection of these interventions is presented in this paper, which analyzes the effectiveness of the various retrofitting solutions, with a specific attention to the force transfer mechanisms between existing structures and strengthening systems. The interventions are divided between column strengthening (based, for example, on RC or steel jacketing) and interventions aimed at providing the building with a suitable earthquake resistant system (based, for example, on either the use of the existing cladding panels or the implementation of new bracing systems). Graphical representations of the analyzed solutions with the relevant construction details are provided.

scholarly journals PRESSAFE-Disp: A Method For The Fast Seismic Assessment of Existing Precast RC Buildings After The Emilia Earthquake Of May 2012

2021 ◽  
Author(s):  
Marco Bovo ◽  
Lucia Praticò ◽  
Marco Savoia
Keyword(s):  
Fragility Curves ◽  
Seismic Assessment ◽  
Structural Elements ◽  
Seismic Behaviour ◽  
Fast Evaluation ◽  
Emilia Earthquake ◽  
Precast Buildings ◽  
Precast Structures ◽  
Precast Elements ◽  
Damage Criteria

Abstract The existing precast reinforced concrete structures, especially those not specifically designed against the earthquakes, have proved to be inadequate to withstand the remarkable seismic demands related to the presence of heavy roof elements. In fact, the cantilever columns entailing large top displacements and the poor devices adopted to connect different precast elements have shown high sensitivity to seismic actions. After the lesson learned from the recent Emilia earthquake of May 2012, causing many collapses and severe damage, reliable seismic design criteria have been established for the design of new precast structures and for the strengthening of the existing ones. Despite this, a large percentage of the existing precast buildings in the Italian territories actually has not been object of interventions and remains in an unsafe condition with regards to the seismic actions. In this context, the methods for a rapid seismic assessment can be very helpful both to estimate the current safety level of large building stocks and to plan the necessary strengthening interventions, possibly at the wide scale of an industrial area. To this aim, the paper proposes a new method, named PRESSAFE-disp (PRecast Existing Structure Seismic Assessment by Fast Evaluation-displacements), for the fast evaluation of the fragility curves of precast structures. The method follows the approach of the PRESSAFE method, but different damage criteria have been introduced in order to take into account the relative displacements and the sliding between different precast elements. The damage criteria considered, applicable to both structural elements and perimeter cladding elements conceived as non-structural elements, have been properly selected in order to capture the damage mechanisms observed during the several building inspections conducted by the authors in the aftermath of the 2012 Emilia earthquakes. In the present configuration, the method allows a comprehensive explanation of the seismic behaviour of the existing precast buildings and could be effectively adopted, for example, in earthquake loss estimations and seismic risk assessments of large Italian industrial areas, as well as of wide seismic-prone territories of the Mediterranean area.

scholarly journals A non-linear element for analysing elastic frame structures at large deflections

2000 ◽  
Vol 22 (1) ◽  
pp. 19-28
Author(s):  
Nguyen Dinh Kien
Keyword(s):  
Beam Theory ◽  
Frame Structures ◽  
Large Deflections ◽  
Force Vector ◽  
Tangent Stiffness Matrix ◽  
Nodal Force ◽  
Axial Forces ◽  
Non Linear Equation ◽  
Non Linear ◽  
Raphson Method

A non-linear finite element for analyzing elastic frame structures at large deflections is presented. A co-rotational technique combined with Classical beam theory with the inclusion of the effect of axial forces is adopted. The element nodal force vector is derived from the strain energy of the element. The element tangent stiffness matrix is obtained by differentiating the nodal force vector, with respect to the degree of freedom (d.o.f.). The obtained formulations have a simple and compact mathematical forms which are easy to implement into a computer program. An incremental interactive technique based on Newton-Raphson method is adopted to solve the non-linear equation and to trace the equilibrium paths of the structures. Numerical examples are presented to show the accuracy and efficiency of the proposed formulations.

Sign in / Sign up

Export Citation Format

Share Document