Bitrix arrFilters

BXarrFilters.php

$arFilter = array();

// Фильтр по дате активности
$arFilter["<=DATE_ACTIVE_FROM"] = ConvertTimeStamp(time(),'FULL'); 

// Логический фильтр
$logic = array("LOGIC" => "OR");
foreach ($periods as $period) {
    $time = ($NowTime-(86400*$period['days']));
    $logic[] =  array("<=DATE_ACTIVE_FROM"=>ConvertTimeStamp($time,'FULL'),'PROPERTY_21'=>$period['value_id']);
}
$arFilter[] = $logic;