<?php 
function strip_tags_disallow($text, $tags = '') {
	$tags	=	array_unique(explode(',',$tags));
	foreach($tags as $tag){
		$pattern = '#\<'.$tag.'.*?\>(.*?)\<\/'.$tag.'\>#si'; 
		$replace = '$1'; 
		$text=preg_replace($pattern, $replace, $text); 
	}
	return $text;
} 
$denemebaslik = 'Türkiye'; 
$demo = 'Burası <strong>İstanbul</strong> <?php echo $denemebaslik; ?>'; 

$deneme2 = strip_tags_disallow($demo,'strong'); 
eval ("?> $deneme2 <?php "); 

?>