How to add bootstrap dropdown to wordpress

I have designed a website using bootstrap framework, and now I am converting it to a wordpress website, the challenge to me is to make dropdown of navigations to appear as designed. I am able to get menus dynamically from wordpress, but I am not to get the dropdowns dynamically as per css style.

Here is my HTML code

<ul class="nav nav-justified menu_bac">
<li class="active"><a href="index.html">Home</a></li>
<li><a href="company.html">Company</a></li>
<li><a class="dropdown-toggle" data-toggle="dropdown" role="button" aria-expanded="false">
      Products <span class="caret"></span>
    </a>
    <ul class="dropdown-menu" role="menu">
      <li role="presentation" class="dropdown-submenu"><a>Grandstream</a>

      <ul class="dropdown-menu">
      <li role="presentation" class="dropdown-submenu"><a>IP-Multimedia <br/>Video Telephony</a>
      <ul class="dropdown-menu">
      <li><a href="gxv3275ipmultimedia phone.html">GXV3275 IP <br/>Multimedia phone</a></li>
      <li class="divider"></li>
      <li><a href="gxv3240multimediaipphone.html">GXV3240 IP <br/>Multimedia phone</a></li>


      </ul>
      </li>

Here is code which i have used to get menus dynamically

<div class="row">
<div class="col-xs-12 col-sm-12 col-md-12 col-lg-12">
<?php wp_nav_menu(array('menu_class' => 'nav nav-justified','container_class' => 'menu_bac')); ?>
</div>
</div>

Would be great help if anybody can guide me to get dropdowns dynamically as per design?