The Study of Post-Fire Load Bearing Capacity of Steel Column under Axial Compression Exposure to one-Side Fire

2011 ◽  
Vol 284-286 ◽  
pp. 330-334
Author(s):  
Jian Feng Chen ◽  
Tian Hua Zhou ◽  
Lin Feng Lu ◽  
Han Heng Wu

The section of steel column under axial compression presents heterogeneous material and its load condition changes after experiencing fire damage of one side. Taking H-section steel column under axial compression commonly used in engineering for study object in this thesis in order to study post-fire residual load bearing capacity, the post-fire eccentric effect of steel column under axial compression exposure to one-side fire is analyzed using the method of equivalent section which considering the change of the material strength after high temperature, the influence of non-uniform temperature field on material properties and the stiffness degradation of member section. Calculation methods of the eccentricity and additional moment are proposed and further given a formula of residual load bearing capacity.

2014 ◽  
Vol 2014 (0) ◽  
pp. _J1810105--_J1810105-
Author(s):  
Keisuke MORI ◽  
Yutaka HASHIOKA ◽  
Masahiko NAWATA ◽  
Takanori YOKOI ◽  
Kazutoshi AKAZAWA

2021 ◽  
pp. 136943322110159
Author(s):  
Bo Wu ◽  
Zhikai Wei

Recycled lump concrete (RLC) made with demolished concrete lumps (DCLs) and fresh concrete (FC) provides a solution for effective waste concrete recycling. To promote the development of precast RLC structures, this study tested a new type of connection for precast concrete columns: connecting the upper and the lower halves of columns with bent longitudinal reinforcements and structural adhesive. In this work the behavior of precast RLC columns with the new connection was studied under axial compression. The axial compressive strength of nine two-part columns was tested. The effects of the degree of bending in the longitudinal reinforcement, the replacement ratio of DCLs and the stirrup spacing were investigated. Tests showed that: (1) the failure mode of precast concrete columns is different from that of cast-in-place columns; (2) when the strength of the waste concrete is close to that of the fresh material, there is no significant difference in the axial compression performance of either precast or cast-in-place columns; (3) the bent longitudinal reinforcement causes the axial load bearing capacity of precast concrete columns to be 4.2%–12.3% lower than that of a similar cast-in-place column; (4) reducing the stirrup spacing has little effect on a precast column’s axial load bearing capacity and ductility; (5) when using Chinese and American codes to predict the axial load bearing capacity of the column, the predicted value should be multiplied by a reduction factor.


Buildings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 30
Author(s):  
Maria Loebjinski ◽  
Wolfgang Rug ◽  
Hartmut Pasternak

The management and preservation of structures in our built environment are central and challenging tasks for practicing engineers. Within the CEN member states (European Committee for Standardization), the so-called Eurocodes form the basis of the design and verification of the load-bearing capacity of structures. Current Eurocodes do not contain special recommendations for existing structures, meaning that the principles for new structures are applied. This can lead to an incorrect estimation of the load-bearing capacity within the semi-probabilistic safety concept. A central task within the investigation and evaluation of existing structures is the strength grading of the material in situ using non-/semi-destructive technical devices. Studies show the potential of the ultrasonic time-of-flight measurement in combination with visual evaluation for an improved grading. The information on the material from an improved grading technique can be used to update the material parameters as a target variable using a measured reference variable. In this contribution, test data from a partner project (spruce, pine, and oak) are analyzed, applying the stochastic grading model of Pöhlmann and Rackwitz. It can be shown that different grading techniques influence the updated distribution function of the material strength within the grade. The results depend on the timber species. Perspectives to develop updated models dependent on the knowledge available are shown and discussed.


Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4310
Author(s):  
Hannes Panwitt ◽  
Horst Heyer ◽  
Manuela Sander

In age-hardened high-strength aluminum alloys, the area with and around a joint has a large impact on the load-bearing capacity of a welded structure. Therefore, in this study the fracture behavior of welded EN AW 6082 T6 plates is investigated experimentally and numerically. From butt joints, smooth and notched tensile specimens as well as shear specimens have been manufactured and tested for the base material (BM), heat-affected zone (HAZ) and fusion zone (FZ). With numerical simulations of these tests, the dependency of the fracture strain on the stress triaxiality is determined, and two phenomenological fracture criteria are calibrated. Whereas the one-parameter Rice–Tracey/Cockcroft–Latham (RTCL) criterion describes the behavior of the tension specimens as accurately as the two-parameter Bao–Wierzbicki (BW) criterion, the BW criterion is more accurate for shear tests. Subsequently, the material model is validated on axial compression tests of welded X-profiles. The experiments comprise tests with different plate thicknesses (8 mm, 10 mm and 12 mm) and varying strain rates (up to 1/s locally), showing the same behavior for all specimens. After crack initiation within the FZ, coalescence of cracks leads to crack growth in axial direction and a subsequent reduction of the load-bearing capacity. This behavior is reproduced well by the numerical simulations with the BW criterion, whereas simulations with the RTCL criterion predict fracture initiation at too high displacements. Overall, the results show the strong influence of the ductility of the FZ on the crushing behavior of welded X-profiles.


2015 ◽  
Vol 744-746 ◽  
pp. 96-99
Author(s):  
Jiong Feng Liang ◽  
Ze Ping Yang ◽  
Ming Hua Hu

In order to further promote the use of recycled aggregate concrete in practice, axial compression tests were carried out for 7 CFRP circular steel tubular confined recycled aggregate concrete columns. The influence of the replace rate of recycled aggregate concrete, the wrapping method on axial compression behavior of CFRP circular steel tubular confined recycled aggregate concrete columns were analyzed. Based on the results of the tests, with the replace rate of recycled aggregate concrete increasing, the specimens have an decreasing trend in the load bearing capacity. The whole CFRP wrapping circular steel tubular confined recycled aggregate concrete columns have higher load bearing capacity than the three stripe wrapping ones.


2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Yuhan Nie ◽  
Yang Wei ◽  
Linjie Huang ◽  
Ying Liu ◽  
Fenghui Dong

AbstractBamboo has been widely used as a load-bearing material in construction; however, there are limited studies on the stability of slender original bamboo columns. Based on the experimental investigation of thirty-nine original bamboo columns, parametric analyses were conducted to investigate the influence of the diameter–thickness ratio, cross-sectional area and slenderness ratio on the axial compression behavior of original bamboo columns. The test results indicate that the failure modes of the columns are substantially affected by the slenderness ratio and diameter–thickness ratio. For columns with the same diameter–thickness ratio, the ultimate bearing capacity was negatively correlated with the slenderness ratio, and the highest reduction rate for the load-bearing capacity caused by the slenderness ratio was 44.39%. Under the same slenderness ratio, when the diameter–thickness ratio increased by 18.75%, the ultimate bearing capacity increased by 82.65%. An excessive slenderness ratio may result in local buckling, leading to underutilization of the material strength when failure occurs and substantially reducing the load capacity of bamboo columns. Local buckling can be mitigated by decreasing the slenderness ratio and increasing the diameter–thickness ratio. According to the test results, the model predicting the compressive bearing capacity of the original bamboo column was proposed considering the slenderness ratio and diameter–thickness ratio, and it was indicated that the proposed model can provide satisfactory predictive results.


2020 ◽  
Vol 62 (1) ◽  
pp. 55-60
Author(s):  
Per Heyser ◽  
Vadim Sartisson ◽  
Gerson Meschut ◽  
Marcel Droß ◽  
Klaus Dröder

2017 ◽  
Vol 68 (1) ◽  
pp. 94-100
Author(s):  
Oana Tanculescu ◽  
Adrian Doloca ◽  
Raluca Maria Vieriu ◽  
Florentina Mocanu ◽  
Gabriela Ifteni ◽  
...  

The load-bearing capacity and fracture pattern of direct inlay-retained FRC FDPs with two different cross-sectional designs of the ponticwere tested. The aim of the study was to evaluate a new fibre disposition. Two types of composites, Filtek Bulk Fill Posterior Restorative and Filtek Z250 (3M/ESPE, St. Paul, MN, USA), and one braided polyethylene fibre, Construct (Kerr, USA) were used. The results of the study suggested that the new tested disposition of the fibres prevented in some extend the delamination of the composite on buccal and facial sides of the pontic and increased the load-bearing capacity of the bridges.


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