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Steel Connections Post-Earthquake Fire Tests Setup
Available online at www.sciencedirect.com
ScienceDirect Procedia Engineering 161 (2016) 133 – 136
World Multidisciplinary Civil Engineering-Architecture-Urban Planning Symposium 2016, WMCAUS 2016
Steel Connections Post-Earthquake Fire Tests Setup Tudor Petrinaa,* a
UTCN, 15 C. Daicoviciu Str., 400020 Cluj-Napoca, Romania
Abstract This paper presents the setting up of a test stand, the design and construction of a furnace and the testing procedure in order to analyse the behaviour of steel beam to column end-plate bolted connections under the post-earthquake fire action. 12 real scale beam – node – column substructures were created for this goal. The main problem was how to simulate the seismic action on the specimens immediately followed by fire action. For the first part, the recommendations inside the document of ECCS – Technical Committee 1 were developed and applied for this case; for the fire action, the special furnace was designed and constructed around the connection. © 2016 Published by Elsevier Ltd. Ltd. This is an open access article under the CC BY-NC-ND license 2016The TheAuthors. Authors. Published by Elsevier (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of WMCAUS 2016. Peer-review under responsibility of the organizing committee of WMCAUS 2016 Keywords: end-plate connections; post-earthquake fire action; testing procedure; furnace; connection deterioration;
1. Introduction After the majority of earthquakes, especially in the urban areas, big fires occurred, sometimes making more calamities than the actual ground movement. During the 1906 San Francisco earthquake, for instance, the post seism fire produced 80% of the total damage; it was the biggest human life loss in California and together with hurricanes Galveston (1900) and Katrina (2005) are the largest natural disasters of the USA. A testing programme was realized in 2014-2015 at the Technical University of Cluj-Napoca, Romania, Faculty of Civil Engineering Testing Facility, on real scale steel beam-connection-column substructures. The programme was aimed to find the behaviour of steel beam to column end-plate connections under the post-earthquake fire action. After
* Corresponding author. Tel.: +40 747929585. E-mail address: [email protected]
1877-7058 © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of WMCAUS 2016
doi:10.1016/j.proeng.2016.08.510
134
Tudor Petrina / Procedia Engineering 161 (2016) 133 – 136
the cyclic action made according to ECCS document [1], the deteriorated connections were immediately subjected to fire, following a real time-temperature curve according to Petrina [2]. New connections were also tested for fire action in order to find differences to the previous deteriorated case. 2. Conception of the testing programme 2.1. Initial design and simulation During earthquakes, the connections are elements of structures that may develop a permanent damage in terms of resistance and stiffness. International literature on fire tests, like in Ramli-Sulong et al. [3], offers good information about the behaviour of steel beam to column connections under fire, but poor information on the post-earthquake fire behaviour of this specific type of connection (with end-plate). The author is aiming at finding the effect of connection’s seismic damage on the post-earthquake fire behaviour of the structure. Firstly, the connection was designed following prescriptions according the European design code EN 1993 [4] and after that, numerical simulations by using the advanced models VULCAN, SAFIR and other were performed on the studied substructure. The simulations were done in order to know whether the conception is right or not, before executing the specimens for experimental testing. The testing procedure follows the recommendations of the document of ECCS [1]. 2.2. The specimen The specimen is a steel beam, column, endplate bolted connection (12 ensembles). The scale was 1:1 - the column is made up by an H type compound profile having the flanges of 15mm thickness and web of 10mm thickness and the beam is of I type compound profile with the thickness of the flanges of 15mm and the web of 8mm. The bolts are of type 10.9 with controlled tense. The connection is a steel beam-to-column bolted connection. The column is 3.0m high and the cantilever beam has the length of 2.0m. Total weight of one specimen was 415kg. The type of the material used is according to Petrina [5], the structural steel S235JR.
Fig. 1. Studied connection according to Petrina [5].
2.3. Required characteristics for the test stand The next main characteristics were followed for the stand: x to assure a pinned fitting of the column base and upper end; x to block the dilatation of the column; x to block possible translations on a direction normal to the plane of the ensemble.
Tudor Petrina / Procedia Engineering 161 (2016) 133 – 136
In the author’s opinion, these main directions assure the conditions inside a real steel frames structure under normal loading. 2.4. Required characteristics for the furnace Studying different articles on fire tests, like Puccinotti et al. [6], we decided to follow these main characteristics for the furnace: x to have sufficient power (avoid electrical furnace for this magnitude of structures); x to have a good thermal insulation (keep temperature of the specimen constant until the mechanic test takes place); x to be constructible around the node and to permit beam movement up and down (in this way the cyclic action is done exactly before fire test); x to be removable after each test (several fire tests were performed). 2.5. Data acquisition Tensions in the node area, magnitude of applied force on the cantilever, the displacement of the free end of the cantilever and the temperature of the steel in the node area, were the main data we wanted to have registered during tests. 3. Setting up stand, furnace and procedure for the tests 3.1. Test stand and furnace Other similar tests for assessing the behaviour of steel beam to column connections under post-earthquake fire were performed at the University of Trento, Italy (the cyclic actions on the specimen) followed by fire tests at BRE, UK in 2009, as presented by Puccinotti et al. [6]. In our case, after the cyclic action, the fire action was immediately applied on the specimen.
Fig. 2. Entire set-up ready for mechanic and fire test according to Petrina and Muntean [7].
The entire set up used for this research was detailed in a previous paper, in Petrina and Muntean [7], and realized in the Testing Facility like in figure 2. Steel test stand, furnace made by bricks with no binder, having a 155kW gas burner, thermocouple, one press having two cylinders for mechanic action, displacement and force translators,
135
136
Tudor Petrina / Procedia Engineering 161 (2016) 133 – 136
equipment HBM Quantum C – MX 1615 and software Catman were used in order to meet all necessary conditions, according to Petrina and Muntean [7]. 3.2. The applied testing procedure The procedure followed the recommendations of ECCS above mentioned document: a) Two preliminary classical monotonic displacement increase tests were performed on the specimen in order to find Fy+,ey+, Fy-,ey- (yield loads in the positive/negative force range, absolute values of the displacement defined as in ECCS [1]); We got Fy+ = 186kN, ey+ = 80mm from the first test and Fy- = 196kN, ey- = 106mm from the second test. b) The third test is a cyclic test with increase of displacement which was decided to have the following characteristics: One cycle in the range 26 mm to -26 mm; One cycle in the range 53 mm to -53 mm; One cycle in the range 78 mm to -78 mm; One cycle in the range 106 mm to -106 mm; One cycle in the range 116 mm to -116 mm; One cycle in the range 126 mm to -126 mm; One cycle in the range 136 mm to -136 mm. At this point, according to the above mentioned ECCS document, the studied specimen has a loading history similar to real actions due to earthquakes. After the third test took place, the furnace was started and the first fire test begun by taking the connection to 600 Celsius degrees and pressing the cantilever end with increasing force. 4. Conclusions The results obtained during the experimental tests were similar to prior numerical simulations made with the help of advanced nonlinear model VULCAN. The stand and furnace met all prior conditions and the behaviour of the specimens was in accordance with prior made experiments on similar structures and with the procedure of ECCS [1]. Aspects on the originality of this research: x design of beam, node, column ensemble and links to the node; x design of the test stand (sections and dimensions of steel elements for the prior computed and expected internal forces); x the way to test the specimen, the position of the specimen and the entire programme management; x the cyclic action on the specimen by using only monotonic pressure devices and displacement translator; x the design of a removable furnace around the connection, with a low cost and using traditional materials, which permits immediate fire test after the cyclic action; x the design of a cooling mode to protect gas burner’s blower when stopping fire. References [1] Technical Committee 1 (ECCS) Recommended Testing Procedure for Assessing the Behaviour of Structural Steel Elements under Cyclic Loads, no. 45, 1986 [2] T. Petrina, Computation of structural fire resistance of steel sections, Acta Technica Napocensis (ISSN 1221-5848). 56 (2013) 119-132 [3] N.H. Ramli-Sulong, A.Y. Elghazouli, B.A. Izzuddin, Behaviour and design of beam-to-column connections under fire conditions, Fire Safety Journal. 42 (2007) 437-451 [4] EN 1993:2005. Design of Steel Structures [5] T. Petrina, Numerical and experimental analysis regarding fire resistance of structures – PhD Thesis, UT Press, Romania, 2014 (in Romanian) [6] R. Puccinotti, O.S. Bursi, J.M. Franssen, T. Lennon, Seismic-induced fire resistance of composite welded beam-to-column joints with concrete filled tubes, Fire Safety Journal. 46 (2011) 335-347 [7] T. Petrina, D. Muntean, Setting up a test stand for steel beam-to-column connections behavior under post-earthquake fire. Proceedings of the Second international conference for PhD students in Civil Engineering. UT Press, ISSN 2392 – 9693, 2014, pp. 29-38.
ScienceDirect Procedia Engineering 161 (2016) 133 – 136
World Multidisciplinary Civil Engineering-Architecture-Urban Planning Symposium 2016, WMCAUS 2016
Steel Connections Post-Earthquake Fire Tests Setup Tudor Petrinaa,* a
UTCN, 15 C. Daicoviciu Str., 400020 Cluj-Napoca, Romania
Abstract This paper presents the setting up of a test stand, the design and construction of a furnace and the testing procedure in order to analyse the behaviour of steel beam to column end-plate bolted connections under the post-earthquake fire action. 12 real scale beam – node – column substructures were created for this goal. The main problem was how to simulate the seismic action on the specimens immediately followed by fire action. For the first part, the recommendations inside the document of ECCS – Technical Committee 1 were developed and applied for this case; for the fire action, the special furnace was designed and constructed around the connection. © 2016 Published by Elsevier Ltd. Ltd. This is an open access article under the CC BY-NC-ND license 2016The TheAuthors. Authors. Published by Elsevier (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of WMCAUS 2016. Peer-review under responsibility of the organizing committee of WMCAUS 2016 Keywords: end-plate connections; post-earthquake fire action; testing procedure; furnace; connection deterioration;
1. Introduction After the majority of earthquakes, especially in the urban areas, big fires occurred, sometimes making more calamities than the actual ground movement. During the 1906 San Francisco earthquake, for instance, the post seism fire produced 80% of the total damage; it was the biggest human life loss in California and together with hurricanes Galveston (1900) and Katrina (2005) are the largest natural disasters of the USA. A testing programme was realized in 2014-2015 at the Technical University of Cluj-Napoca, Romania, Faculty of Civil Engineering Testing Facility, on real scale steel beam-connection-column substructures. The programme was aimed to find the behaviour of steel beam to column end-plate connections under the post-earthquake fire action. After
* Corresponding author. Tel.: +40 747929585. E-mail address: [email protected]
1877-7058 © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of WMCAUS 2016
doi:10.1016/j.proeng.2016.08.510
134
Tudor Petrina / Procedia Engineering 161 (2016) 133 – 136
the cyclic action made according to ECCS document [1], the deteriorated connections were immediately subjected to fire, following a real time-temperature curve according to Petrina [2]. New connections were also tested for fire action in order to find differences to the previous deteriorated case. 2. Conception of the testing programme 2.1. Initial design and simulation During earthquakes, the connections are elements of structures that may develop a permanent damage in terms of resistance and stiffness. International literature on fire tests, like in Ramli-Sulong et al. [3], offers good information about the behaviour of steel beam to column connections under fire, but poor information on the post-earthquake fire behaviour of this specific type of connection (with end-plate). The author is aiming at finding the effect of connection’s seismic damage on the post-earthquake fire behaviour of the structure. Firstly, the connection was designed following prescriptions according the European design code EN 1993 [4] and after that, numerical simulations by using the advanced models VULCAN, SAFIR and other were performed on the studied substructure. The simulations were done in order to know whether the conception is right or not, before executing the specimens for experimental testing. The testing procedure follows the recommendations of the document of ECCS [1]. 2.2. The specimen The specimen is a steel beam, column, endplate bolted connection (12 ensembles). The scale was 1:1 - the column is made up by an H type compound profile having the flanges of 15mm thickness and web of 10mm thickness and the beam is of I type compound profile with the thickness of the flanges of 15mm and the web of 8mm. The bolts are of type 10.9 with controlled tense. The connection is a steel beam-to-column bolted connection. The column is 3.0m high and the cantilever beam has the length of 2.0m. Total weight of one specimen was 415kg. The type of the material used is according to Petrina [5], the structural steel S235JR.
Fig. 1. Studied connection according to Petrina [5].
2.3. Required characteristics for the test stand The next main characteristics were followed for the stand: x to assure a pinned fitting of the column base and upper end; x to block the dilatation of the column; x to block possible translations on a direction normal to the plane of the ensemble.
Tudor Petrina / Procedia Engineering 161 (2016) 133 – 136
In the author’s opinion, these main directions assure the conditions inside a real steel frames structure under normal loading. 2.4. Required characteristics for the furnace Studying different articles on fire tests, like Puccinotti et al. [6], we decided to follow these main characteristics for the furnace: x to have sufficient power (avoid electrical furnace for this magnitude of structures); x to have a good thermal insulation (keep temperature of the specimen constant until the mechanic test takes place); x to be constructible around the node and to permit beam movement up and down (in this way the cyclic action is done exactly before fire test); x to be removable after each test (several fire tests were performed). 2.5. Data acquisition Tensions in the node area, magnitude of applied force on the cantilever, the displacement of the free end of the cantilever and the temperature of the steel in the node area, were the main data we wanted to have registered during tests. 3. Setting up stand, furnace and procedure for the tests 3.1. Test stand and furnace Other similar tests for assessing the behaviour of steel beam to column connections under post-earthquake fire were performed at the University of Trento, Italy (the cyclic actions on the specimen) followed by fire tests at BRE, UK in 2009, as presented by Puccinotti et al. [6]. In our case, after the cyclic action, the fire action was immediately applied on the specimen.
Fig. 2. Entire set-up ready for mechanic and fire test according to Petrina and Muntean [7].
The entire set up used for this research was detailed in a previous paper, in Petrina and Muntean [7], and realized in the Testing Facility like in figure 2. Steel test stand, furnace made by bricks with no binder, having a 155kW gas burner, thermocouple, one press having two cylinders for mechanic action, displacement and force translators,
135
136
Tudor Petrina / Procedia Engineering 161 (2016) 133 – 136
equipment HBM Quantum C – MX 1615 and software Catman were used in order to meet all necessary conditions, according to Petrina and Muntean [7]. 3.2. The applied testing procedure The procedure followed the recommendations of ECCS above mentioned document: a) Two preliminary classical monotonic displacement increase tests were performed on the specimen in order to find Fy+,ey+, Fy-,ey- (yield loads in the positive/negative force range, absolute values of the displacement defined as in ECCS [1]); We got Fy+ = 186kN, ey+ = 80mm from the first test and Fy- = 196kN, ey- = 106mm from the second test. b) The third test is a cyclic test with increase of displacement which was decided to have the following characteristics: One cycle in the range 26 mm to -26 mm; One cycle in the range 53 mm to -53 mm; One cycle in the range 78 mm to -78 mm; One cycle in the range 106 mm to -106 mm; One cycle in the range 116 mm to -116 mm; One cycle in the range 126 mm to -126 mm; One cycle in the range 136 mm to -136 mm. At this point, according to the above mentioned ECCS document, the studied specimen has a loading history similar to real actions due to earthquakes. After the third test took place, the furnace was started and the first fire test begun by taking the connection to 600 Celsius degrees and pressing the cantilever end with increasing force. 4. Conclusions The results obtained during the experimental tests were similar to prior numerical simulations made with the help of advanced nonlinear model VULCAN. The stand and furnace met all prior conditions and the behaviour of the specimens was in accordance with prior made experiments on similar structures and with the procedure of ECCS [1]. Aspects on the originality of this research: x design of beam, node, column ensemble and links to the node; x design of the test stand (sections and dimensions of steel elements for the prior computed and expected internal forces); x the way to test the specimen, the position of the specimen and the entire programme management; x the cyclic action on the specimen by using only monotonic pressure devices and displacement translator; x the design of a removable furnace around the connection, with a low cost and using traditional materials, which permits immediate fire test after the cyclic action; x the design of a cooling mode to protect gas burner’s blower when stopping fire. References [1] Technical Committee 1 (ECCS) Recommended Testing Procedure for Assessing the Behaviour of Structural Steel Elements under Cyclic Loads, no. 45, 1986 [2] T. Petrina, Computation of structural fire resistance of steel sections, Acta Technica Napocensis (ISSN 1221-5848). 56 (2013) 119-132 [3] N.H. Ramli-Sulong, A.Y. Elghazouli, B.A. Izzuddin, Behaviour and design of beam-to-column connections under fire conditions, Fire Safety Journal. 42 (2007) 437-451 [4] EN 1993:2005. Design of Steel Structures [5] T. Petrina, Numerical and experimental analysis regarding fire resistance of structures – PhD Thesis, UT Press, Romania, 2014 (in Romanian) [6] R. Puccinotti, O.S. Bursi, J.M. Franssen, T. Lennon, Seismic-induced fire resistance of composite welded beam-to-column joints with concrete filled tubes, Fire Safety Journal. 46 (2011) 335-347 [7] T. Petrina, D. Muntean, Setting up a test stand for steel beam-to-column connections behavior under post-earthquake fire. Proceedings of the Second international conference for PhD students in Civil Engineering. UT Press, ISSN 2392 – 9693, 2014, pp. 29-38.