Temperature influence on creep of reinforced concrete

Madureira, Edmilson Lira; Fontes, Brenda Vieira Costa

doi:10.1590/S1983-41952020000600001

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ORIGINAL ARTICLE • Rev. IBRACON Estrut. Mater. 13 (6) • 2020 • https://doi.org/10.1590/S1983-41952020000600001 copy

Temperature influence on creep of reinforced concrete

Influência da temperatura na fluência do concreto armado

Authorship SCIMAGO INSTITUTIONS RANKINGS

abstract:

The creep of concrete promotes strains over time in structural members kept under sustained load. It causes the stress decrease on the concrete and the steel stress increase in reinforced concrete members. The moisture content and temperature influence significantly such phenomenon. The creep strains model of the NBR 6118/2014 [1] is, applicable, solely, to those cases of constant stress magnitudes. Reinforced concrete members exhibit variations on the stress magnitudes and, in this way, requires the use of an alternative model for the prediction of the creep strains as the so known the State Model. This report refers itself to temperature influence analysis upon creep strains of reinforced concrete structural members. The results have revealed that temperature speeds up the creep effects and, in this way, the steel yielding caused by the stress increase on the reinforcement bars occurs at earlier ages.

Keywords:
reinforced concrete; thin-walled column; creep; modelling; temperature

Cases	f_ck (MPa)	Temperature (°C)	Moisture Content (%)	$Φ_{v}^{*}$
1	30	20	40	1.63
2	30	40	40	1.63
3	30	60	40	1.63
4	30	80	40	1.63
5	30	100	40	1.63
6	30	20	60	0.92
7	30	40	60	0.92
8	30	60	60	0.92
9	30	80	60	0.92
10	30	100	60	0.92
11	40	20	40	1.63
12	40	40	40	1.63
13	40	60	40	1.63
14	40	80	40	1.63
15	40	100	40	1.63
16	40	20	60	0.92
17	40	40	60	0.92
18	40	60	60	0.92
19	40	80	60	0.92
20	40	100	60	0.92

Cases	Displacement (mm)			Final age (days)
Cases	Immediate	Creep (90 days)	Final creep	Final age (days)
1	2.05	2.26	5.14	860
2	2.05	2.70	4.69	379
3	2.05	3.02	5.10	379
4	2.05	3.29	4.34	176
5	2.05	3.51	4.60	176
6	2.05	2.14	4.70	2000
7	2.05	2.50	4.80	2000
8	2.05	2.76	4.83	2000
9	2.05	2.96	4.85	2000
10	2.05	3.13	4.86	2000
11	2.37	2.64	4.76	379
12	2.37	3.16	4.23	176
13	2.37	3.54	4.72	176
14	2.37	3.85	3.85	90
15	2.37	4.11	4.11	90
16	2.37	2.50	4.10	379
17	2.37	2.93	4.63	379
18	2.37	3.23	4.09	176
19	2.37	3.47	4.35	176
20	2.37	3.66	4.56	176

Cases	Concrete Stress (MPa)			Final age (days)
Cases	Immediate	Creep (90 days)	Final	Final age (days)
1	14.8	14.1	13.0	860
2	14.8	13.9	13.2	379
3	14.8	13.8	13.0	379
4	14.8	13.7	13.3	176
5	14.8	13.6	13.2	176
6	14.8	14.1	12.9	2000
7	14.8	14.0	12.8	2000
8	14.8	13.9	12.7	2000
9	14.8	13.8	12.7	2000
10	14.8	13.7	12.7	2000
11	19.8	18.9	18.2	379
12	19.8	18.8	18.4	176
13	19.8	18.6	18.2	176
14	19.8	18.5	18.5	90
15	19.8	18.4	18.4	90
16	19.8	19.0	18.3	379
17	19.8	18.8	18.1	379
18	19.8	18.7	18.3	176
19	19.8	18.6	18.2	176
20	19.8	18.5	18.2	176

Cases	Reinforcement stresses (MPa)			Final age (days)
Cases	Immediate	Creep (90 days)	Final	Final age (days)
1	143	301	499	860
2	143	331	470	379
3	143	354	498	379
4	143	372	446	176
5	143	388	464	176
6	143	292	470	2000
7	143	318	477	2000
8	143	336	479	2000
9	143	350	481	2000
10	143	361	482	2000
11	166	350	496	379
12	166	386	461	176
13	166	413	495	176
14	166	434	434	90
15	166	453	453	90
16	166	340	452	379
17	166	370	489	379
18	166	391	451	176
19	166	408	470	176
20	166	421	484	176

IBRACON - Instituto Brasileiro do Concreto Instituto Brasileiro do Concreto (IBRACON), Av. Queiroz Filho, nº 1700 sala 407/408 Torre D, Villa Lobos Office Park, CEP 05319-000, São Paulo, SP - Brasil, Tel. (55 11) 3735-0202, Fax: (55 11) 3733-2190 - São Paulo - SP - Brazil
E-mail: arlene@ibracon.org.br

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[1] Corresponding author: Edmilson Lira Madureiras. E-mail: edmadurei@ct.ufrn.br