ISSN / EISSN : 0965-0911 / 1751-7702
Published by: Thomas Telford Ltd. (10.1680)
Total articles ≅ 613
Latest articles in this journal
Structures Buildings, Volume 173, pp 1-11; https://doi.org/10.1680/jstbu.17.00124
This paper investigates the structural capacity enhancement of concrete column by reinforced concrete jacketing. In view of investigating structural capacity and integrity of jacketed column, a total twelve retrofitted column samples with different jacket thickness were experimentally tested. Samples are prepared with different types of interface including no surface treatment, addition bonding chemical, roughening of old surface, application of welded ties, and changes in clear cover to investigate the influence of interface bonding between new and old concrete. Analytical equations for jacketed columns are formulated as per elastic principle maintaining strain compatibility at the interface in addition to concrete modeling. Column interaction diagrams as formed by analytical equations are compared and verified with existing Japanese code and available Finite Element software packages. Experimental investigation shows that failures occur relatively earlier at the column interface than the core of the retrofitted column. Comparative study in terms of interaction diagram shows that experimental result well agrees with the computed analytical result but deviates from the FE analysis. Finally, an interface bonding reduction coefficient in the range of 0.65-0.88 is proposed for RC jacketed column subjected to different types of interface.
Structures Buildings, Volume 173, pp 63-75; https://doi.org/10.1680/jstbu.17.00106
A hybrid composite pre-cast concrete column called SMART column has been developed to increase the productivity of the tilt-up construction method. SMART column, consisting of three pre-cast concrete members and steel joints connecting them, covers three stories per unit. The joints where concrete is not poured during production consist of connection steel and rebar installed through three pre-cast concrete members, and are weak areas for possible failure due to stress concentration. Although SMART column is designed safely through sufficient structural review, failure can occur during the tilt-up process adversely affecting cost and time. This paper presents the field experiment results on SMART column for its safe erection by measuring the embedded rebar strains using five different lifting procedures during the tilt-up process. Based on experiment investigations, all five lifting procedures exhibited small strain behaviours in reinforcing bars, indicating no significant bending was observed during the lifting procedures, which proved the safe erection of a SMART column.
Structures Buildings, Volume 172, pp 922-934; https://doi.org/10.1680/jstbu.18.00131
This paper presents an experimental investigation to assess the influence of Soil-Structure Interaction (SSI) on an unreinforced masonry structure under train induced vibrations. For this purpose, a structure near railway line was instrumented and monitored under five railway traffic vibrations. The measured vibrations were used to estimate the modal properties using frequency domain decomposition technique. The variation in estimated modal properties against varying excitations indicated that the dynamic response depends on the source of excitation. Two Finite Element (FE) models were also developed and updated through manual tuning, one with the fixed base and other with flexible base accounting for SSI. The modal properties and response time histories measured through experimentation were compared to those predicted by detailed three dimensional FE models. The comparison between the base input force, base moment and peak displacement of both FE models was also performed. The results concluded that the effect of SSI on the fundamental mode shape and in the prediction of accurate response time histories of the investigated structure was observed to be significant. However, the effect on modal frequencies, base input force, base moment and peak displacement of the investigated structure under train induced vibrations was observed to be very low.
Structures Buildings, Volume 172, pp 882-901; https://doi.org/10.1680/jstbu.18.00055
Structures Buildings, Volume 172, pp 857-858; https://doi.org/10.1680/jstbu.2019.172.12.857
Structures Buildings, Volume 172, pp 871-881; https://doi.org/10.1680/jstbu.18.00016
In this paper, a seismic evaluation procedure based on an energy balance concept is presented for the cable-stayed bridge. In this method, the capacity curve obtained from the modal pushover analysis of the cable-stayed bridge is converted to modal energy capacity diagram. Then, by intersecting this diagram and the energy demand diagram for a selected ground motion, the dynamic target point is obtained. This method is employed on the cable-stayed bridge under Imperial Valley earthquakes with different peak ground motion, and the seismic demands are compared with the results from modal pushover and nonlinear response history analyses. It is observed that this energy balance method can estimate the seismic responses under the selected ground motions with proper accuracy. It should be noted, the OpenSees software is employed for modeling and analyzing of the cable-stayed bridge.
Structures Buildings, Volume 172, pp 859-870; https://doi.org/10.1680/jstbu.18.00010
This paper presents a Finite Element Analysis (FEA) model and an analytical model to estimate the ultimate flexural strength of Reinforced Concrete (RC) beams with corroded compression bars. Both models account for the deteriorated material properties and geometry. The above models were verified against the available experimental data, and showed good agreement. The analytical model was employed to study the effects of corrosion length, corrosion level, concrete compressive strength, and concrete cover on the ultimate flexural strength of RC beams. Over 670 cases were investigated to estimate the influence of the above variables on the ultimate flexural strength of reinforced concrete beam with corroded compression steel reinforcement. The result of this investigation suggests that corrosion of compression steel reinforcement leads to a maximum flexural strength reduction of 20 percent, in which roughly 15 percent is due to the spalling of the concrete cover on the compression side of the cross-section.
Structures Buildings, Volume 172, pp 781-788; https://doi.org/10.1680/jstbu.18.00080
This article presents the results of experimental study on the effect of mechanical and durability properties of concrete made with ordinary portland cement with partial replacement by nanosilica. Concrete mixes were made of varying nanosilica content at a constant water binder ratio of 0.40. Test outcomes demonstrate that the inclusion of 3% nanosilica as a partial replacement of cement enhances the maximum mechanical properties and reduces the permeability depth and water absorption value of concrete which results in improved performance of concrete. Permeability depth and water absorption of the concrete was reduced by 42.85% and 36.84 % as compared to normal concrete. Carbonation depth was reduced with nanosilica replacement leading to enhanced durability property. Such enhancement in mechanical and durability properties was mainly due to high degree of fineness and more pozzolana activity of nanosilica.
Structures Buildings, Volume 172, pp 819-835; https://doi.org/10.1680/jstbu.17.00138
Substantial damage to buildings from seismic pounding is a result of earthquakes in many urban areas. This study investigated the effects of pounding in low-rise buildings, which have been individually designed for seismic resistance, using a three-dimensional numerical model. The poundings between the heavier and lighter buildings were conducted in 4 cases under the floor to floor collision and zero separation gap, and the total heights of the buildings were varied. The ratio of the story mass between the heavier to the lighter buildings in all cases is 1.7. The results demonstrated that the heavier buildings were almost unaffected from the collision, and that seismic design without pounding consideration is acceptable. Nevertheless, the pounding had more influence on the lighter buildings. A significant increase of the inter-story drift and the story shear force can be found. At the top floor of the lighter building, the inter-story drift and the story shear force are increased in the range of 35-73% and 20-46%, respectively, compared with the no pounding events. In addition, severe damages at beam-column joints are found. Hence, the lighter buildings need special attention under a seismic pounding event.
Structures Buildings, Volume 172, pp 805-818; https://doi.org/10.1680/jstbu.18.00057
Cold-formed hollow sections have a lower resistance capacity than hot-rolled profiles due to their welded seams. However, using design codes for such sections usually leads to an uneconomical and conservative structural design for compressive members. This paper presents a series of numerical analyses of standard and concrete-filled cold-formed columns to understand and evaluate their performance. A numerical model was developed calibrated against experiments considering residual stresses, initial geometric imperfections and material properties. The developed numerical model was able accurately to represent the experimental results in terms of failure mode, deformed shape and compressive resistance. Based on these results, an alternative buckling curve is proposed for plain steel and steel–concrete composite columns. This design curve was determined from the results of a parametric study and led to the use of new values of imperfection factor and initial non-dimensional slenderness for the Eurocode design procedure. A reliability index was also evaluated to estimate the scope and validity of the proposed curves.