Numerical Analysis of Portal Steel Frames with Steel- Rubber Bolt Connections Subjected to Seismic Loading

Abstract

Abstract The effect of earthquakes on structures, and possibility the increase of these earthquakes in the recent years in the state of Iraq, and the lack of design and implementation in line with the requirements of seismic design make it necessary to study how to reduce these seismic disasters and delay the time of building failure to give more time to evacuate the building and thus keep people safe. This study aims at reducing the seismic effect on steel structures specifically by using a damping system for linking the beam-column connection, and the base connection This study includes a numerical analysis using the ABAQUS/CAE 2017 program for several models related to steel structures. The results of simulating these frames agree well with the experimental models. Therefore, it can be established that the ABAQUS program is capable of simulating the behaviour of steel frames with the steel/rubber bolts subjected to both horizontal and inclined cyclic loads. The study also includes a set of variables that are studied by conducting a finite element method, including four groups. The first group represents time history analysis, the second shows the models with steel/rubber bolts at the base connection and beam-column connection, the third offers the increase in the number of bolts to which rubber has been added in the beam-column connection tested under a horizontal cyclic load, and the fourth one differences in bolts location and the details tested under horizontal and inclined cyclic loads II The results have shown that the acceleration value of the reference model tested under the seismic load without rubber is 62.016% which is higher than that of the model tested under seismic load which contains two rubber-sleeved bolts in the beam-column connection When rubber is added to the base connection and the beam-column connection, the residual displacement, cumulative energy, drift ratio, and the ductility index of the models containing rubber-sleeved bolts at the base and beam-column connections are (23.805, 256.819, 194.964, and 194.95)%, respectively which is higher as compared to the model that has rubber-sleeved bolts in base connection This means that the model has become more flexible and has a greater ability to dissipate energy resulting from the seismic effect The comparison between the results of the models tested under a horizontal cyclic load and those of models tested under an inclined cyclic load, which takes into account the vertical component of the surface seismic wave, showed that the effect of this vertical component is significant and cannot be neglected The addition of rubber around one bolt in the beam-column connection with (4 and 5) bolts gives a behaviour and a resistance closer to that of the connection with all rubber-sleeved bolts The technique of adding rubber to the connection in order to resist seismic loads gives outstanding results in terms of behaviour , resistance and the facility of installation, maintenance, and sustainability. Also, rubber is highly efficient in stress redistribution and is able to absorb energy